Infant Health and Development Program for Low Birth Weight, Premature Infants: Program Elements, Family Participation, and Child Intelligence

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454 PEDIATRICS Vol. 3 No. March 1992

Infant

Health

and

Development

Program

for Low

Birth

Weight,

Premature

Infants:

Program

Elements,

Family

Participation,

and

Child

Intelligence

Craig 1. Ramey, PhD*; Donna M. Bryant, PhD; Barbara H. Wasik, PhD;

Joseph

J.

Sparling, PhD; Kaye H. Fendt, MSPH; and

Lisa M. LaVange, PhD

ABSTRACT. The Infant Health and Development Pro-gram was an eight-site randomized controlled trial test-ing the efficacy of early intervention to enhance the cognitive, behavioral, and health status of low birth

weight, premature infants. The 377 intervention families

received for the first 3 years of life: (1) pediatric follow-up, (2) home visits, (3) parent support groups, and (4) a systematic educational program provided in specialized child development centers. The control group (n = 608)

received the same pediatric follow-up and referral serv-ices only. This paper describes the delivery of the inter-vention and its outcomes. A Family Participation Index that was the sum of participation frequencies in each of the program modalities unique to the intervention re-vealed that program implementation was not different across the eight sites. Index scores did not vary system-atically with mother’s ethnicity, age, or education or with child’s birth weight, gender, or neonatal health status; but they were positively related to children’s IQ scores at age 3. Only 1.9% of children of families in the highest tercile of participation scored in the mentally retarded range (IQ 70), whereas 3.5% and 13% of children in the middle and lowest participation terciles, respectively, scored in the retarded range. Similar findings were ob-tamed cn,. borderline intellectual functioning. These findings art consistent with previous research linking intensity of intervention services with degree of positive cognitive outcomes for high-risk infants. The determi-nants of variations in individual family participation remain unknown. Pediatrics 1992;89:454-465; low birth

weight, prematurity, intervention, intelligence quotient,

I

amily, systems theory, treatment, prevention.

ABBREVIATIONS. LBW, low birth weight; IHDP, Infant Health

and Development Program; FPG, Frank Porter Graham Child

Development Center.

Low birth weight (LBW) premature infants are at

increased risk for poor cognitive development.’

Pe-diatric and educational interventions increasingly are

thought to be promising means for improving

cogni-tive development in infants at biologic as well as

social risk.2 Some single-site home-based early

inter-ventions have had modest effects on the cognitive

performance of LBW infants.36 Highly similar

pro-From the ‘ Civitan International Research Center and Sparks Center for

Developmental and Learning Disorders, University of Alabama at Binning-ham and Frank Porter Graham Child Development Center, University of

North Carolina at Chapel Hill.

Received for publication Sep 17, 1990; accepted Jan 29, 1991.

Reprint requests to (C.T.R.) Director. Civitan International Research Center,

P0 Box 313, UAB Station, Birmingham, AL 35294.

grams,7’8 however, have not detected measurable

ben-efits. Only recently has a randomized trial been

con-ducted to determine the efficacy for LBW premature

infants of combining home visits, parent support, and

a comprehensive educational curriculum within child

development centers. This strategy builds on earlier

findings that disadvantaged children may benefit

most from combining home visits and child

devel-opment center programs.9”#{176}

This randomized, controlled trial, known as the

Infant Health and Development Program (IHDP),

was conducted in eight sites and involved 985

fami-lies. Children in the intervention group demonstrated significantly higher Stanford-Binet IQ performance,

fewer problem behaviors as reported by mothers on

the Behavior Problem Checklist,” and a small but

significant increase in mother’s report of child’s

mor-bidity which was entirely accounted for by acute,

nonserious illnesses for ages 2_3.12 At 3 years of age children with birth weights of less than 2001 g

aver-aged a 6.6-point IQ advantage as a function of

as-signment to this comprehensive early intervention

program. Children with somewhat heavier birth

weights, from 2001 to 2500 g, showed twice as much

benefit, scoring an average of 1 3.2 IQ points higher than did control children who received pediatric sur-veillance and referral services.

These scientific effects clearly have policy

implica-tions. Beyond demonstrating efficacy, this paper will

consider three key issues. First, the full array of

inter-vention components will be described and related

to the hypothesized causal pathways in children’s

development. Second, intellectual performance of

treated children will be considered in relation to child and family characteristics that might have influenced

the program’s functional attractiveness and, hence,

potential impact. Third, we will address the question of whether amount of participation in a comprehen-sive early intervention program, assessed at the mdi-vidual family level, relates to child IQ and behavioral

competence at 3 years of age. Does program

partici-pation combine with initial child and family charac-teristics, either additively or interactively, to predict cognitive performance and behavioral competence?

BIOSOCIAL SYSTEMS THEORY AS A

CONCEPTUAL

FRAMEWORK

FOR

THE

IHDP

Contemporary theories of child development

em-phasize that cognitive and social development of

young children are influenced by multiple factors (ie,

the child’s genotype and health status, family and

at Viet Nam:AAP Sponsored on September 1, 2020

www.aappublications.org/news

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ARTICLES 455

cultural environments) that interact as parts of a larger

ecosystem.’3”4 Reciprocal interactions between

in-fants and caregivers are seen as particularly important

for cognitive development,’5 which is maximized

when interactions are appropriately matched to the

developing intellectual structures within the child.16 Consistent with these ideas, Fig 1 illustrates four levels of influence in our hypothesized model of early

development: (1) biologic and social historical

con-texts of the child and care givers; (2) their current status; (3) the potential transactions among the child,

caregivers, and their environments; and (4) the

de-velopmental progress of the child and caregivers,

including their cumulative memories and interpreta-tions of transactions. The creation and

implementa-tion of the IHDP intervention model was guided by

this biosocial systems model.

We include the historical level of influence in the

model for conceptual completeness, although in an

educational intervention such as ours, these factors

cannot be manipulated. They do, however, directly

affect children and their care givers and should be

acknowledged.

Although multiple influences from conception

on-ward are recognized as important in this model, we

hypothesize that the behavioral interactions between infants and adults are the most important influence on cognitive development.’7 Family and environmen-tal stresses and supports may impinge on these

infant-caregiver transactions in ways that enhance or limit

the transactions and the child’s potential develop-ment, but the caregiver-child interaction is the key.

Infants and toddlers bring to the transactions a

tendency to be most influenced by frequently

occur-ring events in the here and now. For early interven-tion to be maximally effective, infants need to spend

significant amounts of time in developmentally

sup-portive and optimally challenging activities with

adults. Low birth weight premature infants, because

of their cognitive and motor delays,2 may require

special tailoring or pacing of these interactions to

maximize developmental appropriateness.

Caregivers bring to the transactions many

char-acteristics, both general and parent-specific, that

po-tentially influence the interactions. Mothers’

education’ ‘‘‘‘8 and problem-solving abilities’ have been related to the cognitive outcome of LBW infants.

Fig 1. Biosocial systems model for early development. CNS, central

nervous system.

Mothers’ socioeconomic status and use of social

supports2#{176} may influence transactions with their

in-fants. The use of developmental encouragement2’ and

knowledge about LBW infants and developmental

milestones22 may also be related to LBW children’s

development. An early intervention program might

directly or indirectly modify one or more of these

characteristics. Knowing that LBW infants are rated

as less socially responsive than normal birth weight

babies23 and that mothers of preterm infants tend to

display less positive affect,’9 a systematic intervention

might improve transactions by changing both

expec-tations and behaviors of parents. Any intervention

that is perceived by the mother as increased social

support might also positively affect the LBW infant.24

RATIONALE FOR THE IHDP MODEL OF EARLY

INTERVENTION

Within the IHDP intervention program, health and

educational services were viewed as extrafamilial

sup-port mechanisms. The health support was in the form

of expert LBW pediatric surveillance, regular

devel-opmental follow-up, and comprehensive referrals for

special evaluations and treatments. The educational

support provided to the parents was via frequent

home visits by trained professionals and facilitation of parent group meetings. Educational intervention

for the children occurred through participation in a

systematic program in special child development

cen-ters.

Problem-solving training, a major component in

the home visit program, was designed to increase

parents’ general adaptational skills as well as their parent-specific skills. Developmental encouragement was fostered via a specified and flexible educational curriculum with demonstration, practice, discussion,

and feedback. To encourage continuity between home

and center, the child development centers were

staffed by experienced, family-oriented, early

child-hood educators who were applying the same

educa-tional curriculum-known as Partners for Learning

(described below)-that was coordinated with

par-ents via home visits.

By beginning the IHDP intervention at hospital

discharge and continuing to age 3, the program

em-phasized the importance of early and consistent

ex-periences for LBW infants and their families.25 By

providing pediatric, educational, and family support

services, the parentingiesources of families and the

developmental status of infants were directly

pro-moted; thereby, according to our model, maximizing

the likelihood of positive child-caregiver

transac-tional experiences hypothesized to support early

nor-mative cognitive and behavioral development of LBW

and premature children. Emotional elements also

were emphasized by promoting frequent, warm,

de-velopmentally appropriate, and emotionally positive

exchanges. The research hypothesis was that

in-creased occurrence of developmentally appropriate, positive social interactions, guided by knowledgeable

parents and professional educators, would enhance

the cognitive and behavioral development of LBW

children. We also hypothesized that more frequent

participation in the multiple intervention modalities at Viet Nam:AAP Sponsored on September 1, 2020

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456 INFANT HEALTH AND DEVELOPMENT PROGRAM

would be associated with more positive cognitive and

behavioral outcomes.

METHODS Participants and Research Design

In 1983, eight medical institutions were selected by competitive review to participate in a randomized and controlled efficacy trial of early intervention. The goal was to enroll approximately 135

LBW (2500 g) premature infants (37 weeks gestation) at each

site. The projected overall sample size was based on an estimated

effect size of one-half a standard deviation difference between the

means of the intervention and follow-up groups on cognitive

outcome, with a two-tailed power of 99% for a single dependent variable.26

The coordinating center for the program, the National Study Office, was located at Stanford University. The National Study Office was responsible for the scientific management of the study

and for the collection and analysis of child outcome data. Program

development, implementation, and monitoring were the

responsi-bility of the IHDP Program Development and Implementation Office located at the Frank Porter Graham Child Development

Center (FPG) of the University of North Carolina at Chapel Hill.

Families were contacted and recruited during the infant’s stay in the neonatal nursery and intervention began immediately after the infant’s discharge from the hospital. Recruitment and enroll-ment was conducted over an 8-month period and the full interven-tion continued until the youngest child at each site reached 36 months of age corrected for prematurity. (Note: all ages referred to

hereafter are corrected ages.) The endpoint assessment occurred at

36 months for all infants during the experimental phase of the program.

Infants were randomly assigned by a computer program at Stanford University with approximately one third of the sample to the intervention group (n = 377) and two thirds to the follow-up

group (n = 608). A computer-based procedure27 for monitoring

enrollment was used to balance the two groups for birth weight,

gender, maternal age, maternal education, and maternal race and

thereby reduce the probability of initial bias between the two groups.2’ Full details of sample recruitment, composition, and re-tention are presented elsewhere,’2

Of the eligible families, 75.7% were successfully recruited and 93% of those recruited in each group continued participation through 36 months. As Table 1 shows, and as was anticipated,

there was great variability in the sample on all initial status

char-acteristics at each site. Summing across sites and experimental groups, we can see from Table 1 that the typical infant weighed

about 1800 g and was 33 weeks gestational age. Approximately

half the infants were of each gender. Mothers were, on average, 25 years old and high school graduates. Approximately 53% of the sample mothers were black, 10% were Hispanics, and the remain-ing 37% were whites, Asians, and others.

An analysis of the 317 eligible infants whose parents chose not

to enroll in the study showed that they did not differ from enrolled infants on gender, mother’s age, or single vs twin birth status.

However, nonenrolled infants were significantly more likely to be

white, to be of higher birth weight, and to be from one specific site

(Harvard).29

The research design included stratification by eight sites and

two birth weight groups: heavier infants, weighing 2001 to 2500 g, and lighter infants, those weighing 2000 g or less. Two-thirds of the sample was lighter because those infants were expected to be at greater risk for developmental problems relative to the heavier infants. Because the primary research question was whether the combination of pediatric monitoring and referral, home visits,

parent groups, and systematic educational intervention was more

effective than high-quality pediatric monitoring and referral serv-ices by themselves, both groups received the same pediatric

sur-veillance in the same follow-up clinics, which were specifically

established for this study.

IHDP Program Structure and Functioning

We conceptualized the IHDP intervention within a

program evaluation framework that distinguished

program structure from program functioning. Program

structure refers to both the modalities of the

interven-tion and the content of the intervention. The four

main intervention modalities were pediatric

follow-up and referral, home visits by well-trained

profes-sionals, parent support groups, and child

develop-ment centers operated by early childhood educators. Program content consisted of the resources, materials,

and procedures provided by the IHDP. Table 2

pro-vides a brief summary of the program’s structure.

Program functioning refers to the way the IHDP

program actually operated at each site and the way

in which individual children and families actually

participated. Program functioning will be discussed in detail in the “Results’ section of this paper. Unfor-tunately, it has been an infrequently reported aspect

of early intervention programs, which may account,

at least in part, for differences in reported outcomes from previous interventions. In the IHDP,

participa-tion was measured by documenting the type and

frequency of program contacts with family members.

Because consistency of treatment practices in a

randomized, multisite intervention is crucial,

inter-vention delivery was monitored on a systematic and

frequent basis. The major strategies for minimizing site-to-site variation included using explicit materials

and procedures, ensuring a well-prepared and

con-sistently supported professional staff, and providing explicit and frequent feedback to the sites. Evidence of program drift was noted and, if possible, corrected.

Intervention Modalities

Pediatric Follow-up. As shown in Table 2, infants in

both treatment groups received the same pediatric

follow-up protocol, including medical,

develop-mental, and social assessments on eight occasions

between 40 weeks and 36 months corrected age. At

each clinic visit, the mother reported the child’s health

and developmental functioning as well as social and

demographic characteristics of the family, through

standardized interviews. IHDP staff made clinical

referrals to other services (eg, physical therapy,

coun-seling) for both treatment groups as they judged

appropriate and they assisted families in obtaining

those services. All other IHDP intervention

proce-dures were provided only to the intervention group.

Family Support via Home Visits. Table 2 describes

the protocol for home visits, the qualifications of

home visitors, and a brief characterization of the

program content. The goals of the home visit program were (1) to provide emotional, social, and practical support to parents, as adults; (2) to provide parents

with developmentally timed information about their

LBW child’s development; (3) to help parents learn

specific ways to foster their child’s intellectual, phys-ical, and social development; and (4) to help parents discover creative ways to cope with the responsibili-ties of caring for a developing and, initially, vulnera-ble child.

To accomplish these goals college graduates with

previous experience as home visitors were recruited. A handbook3#{176} was developed for home visitors and preservice training in basic clinical skills was part of their preparation. Clinical skills were further

devel-oped and reinforced in annual 3-day training

meet-ings through workshops, role-playing, supervision, and written materials.3’ Home visitors were supported at Viet Nam:AAP Sponsored on September 1, 2020

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by qualified education directors and clinical staff at each site. Individual supervision and team meetings

occurred weekly. At some sites male escorts

accom-panied home visitors on some home visits as a safety precaution.

A curriculum for very young LBW infants (24 weeks

to 40 weeks gestational age), Early Partners,32 as well as a curriculum for infancy and early childhood (birth to 36 months), Partners for Learning,33 were salient

components of the home visiting program. These

materials contained a series of learning activities that

emphasized developmentally appropriate, positive

adult-child transactions. Through discussion and

re-flection, home visitors and parents selected activities

appropriate to the child’s developmental status. The

choice of activities was based on an educational phi-losophy that emphasizes learning as a natural process.

Undergirding the general educational philosophy are

seven educational principles and 325 previously

val-idated educational activities for the first 3 years of life. Once infants began attending the child develop-ment centers, home visitors also helped to coordinate center and home activities.

Child Development Centers. Each IHDP site

estab-lished and operated a full-day child development

center for the exclusive use of children in the

inter-vention group. Each center met, and exceeded, all

current state licensing requirements. Table 2 also sum-marizes the child development center program.

Children began to attend the centers when they

turned 1 2 months of age. If the site staff had any

concerns that a child’s health might be jeopardized by attending group care, the child’s health data were

sent to a committee of pediatricians “blinded’ to the

group status of the children. Of the 17 consultations

requested, 3 intervention children and 3 follow-up

children were judged to be at risk for health problems

in group care, and IHDP staff urged these parents not

to enroll their children in any group care at that time.

When these children were reviewed again at later

points, 4 were judged healthy enough to participate in a group program.

The education directors at each site were responsi-ble for recruiting and hiring qualified educational staff

(see Table 2) and for maintaining the morale of the

teaching staff and adherence to the research protocol. Before the IHDP centers opened, all education direc-tors and teachers participated in preparatory sessions at FPG. Videotapes of the training sessions were made for use by each site in orienting assistant teachers and

any new teachers hired as replacements later in the

program. Onsite consultation, accompaniment on

home visits, and classroom observations were

con-ducted by FPG approximately four times per year per

site. A formal site visit dealing with all aspects of the

intervention and follow-up protocol was conducted

each year by a team of four to eight persons

repre-senting the National Study Office, the Program

De-velopment Office, and the National Advisory

Com-mittee.

The teacher and assistant teacher in each classroom

organized the classroom program by planning and

implementing the curriculum, maintaining a

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458 INFANT HEALTH AND DEVELOPMENT PROGRAM

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ment, and cooperating and coordinating with parents and home visitors in planning educational activities. These activities were recorded daily and electronically

transmitted weekly to the Program Development

Of-fice for program monitoring.

Special care was taken in developing the health

and safety procedures in the centers. IHDP staff

followed standardized health and safety procedures

(such as hand-washing after each diaper change, daily

toy washing with germicides, and detailed weekly

inspections). These procedures were specified in a

50-page operations manual and monitored weekly by

the education directors, the nurses, and FPG staff via

frequent telephone conversations. In addition to

an-nual cardiopulmonary resuscitation certification for

all teaching and transportation staff, in-service health training sessions were part of the weekly staff meet-ings attended by all teachers, assistant teachers, IHDP

nurses, and social workers. (The nurses and social

workers, as part of the pediatric follow-up team, were

also available to the children and families in the

follow-up group.)

Because child development center participation was

crucial to the test of the efficacy of the intervention

program, each site provided transportation for every

child who needed it. Five sites operated their own

transportation systems by leasing vans or minibuses

and hiring their own drivers and riders. Three sites

subcontracted the transportation to a local agency

experienced in transporting young children. Across

sites, between 80% and 100% of the children were

transported by the centers.

Parent Groups. Parent meetings were held every

other month from the time the child development

centers opened until they closed. Meals were often

arranged as part of the meeting. Transportation was

provided for those parents who needed it. All family

members were invited and child care was provided

for all young children in the families to encourage

full participation. Parent groups were planned to

serve as family support groups in which parents could

share information and concerns about child rearing

and as an opportunity to learn about specific topics

in child development and local community resources.

Intervention Content

Parent Support. The parent support component of

the intervention was an integral part of the home

visits, parent groups, and child development centers.

The program’s goal was to support and to encourage

parents by providing informational, instrumental,

so-cial, and emotional assistance based on the perceived needs of the parents. A total of 25 144 intervention

home visits over 3 years were made in the IHDP. A

review of the standardized home visit report forms

and clinical notes revealed that families in the IHDP

faced almost every imaginable positive and negative

family situation at one time or another. Because the

family situations were so diverse and frequently so

emotionally demanding (eg, in cases of suspected

child abuse, drug involvement, spouse abuse, or

di-vorce), the activities of the home visitors were

super-vised in individual and group sessions weekly by the

education director to provide them with professional

and personal support. Teachers were supervised

bi-weekly. These meetings were also used to review the

program’s goal of supporting, not supplanting, the

parents’ roles in their children’s growth and devel-opment.

Parent Problem Solving. The problem-solving

ap-proach of IHDP was based on a program known as

Problem Solving for Parents.34 This program

compo-nent was developed to help parents learn to cope

effectively with personal issues that they identified

as important to their functioning as parents. The

approach was designed to help parents consider their

own goals, challenges, and problems; set priorities; and develop strategies to solve problems. Seven

proc-esses used in interpersonal problem solving were

presented to parents in nontechnical language as part of a general model for coping with day-by-day family concerns: (1) problem identification, (2) goal selection, (3) generation of alternative solutions, (4) evaluation of solutions, (5) decision making, (6) actual

perform-ance, and (7) evaluation of outcome. During the

course of the intervention program, home visitors

helped parents to identify concerns and goals and to

address them using a systematic plan. These plans

were concerned with positive parental opportunities

as well as ‘problems’ or impediments to personal

growth.

Partners for Learning Curriculum. The activities used

in the home visits and in the child development

centers were designed to represent a spectrum of

developmental skill areas. The skill areas are

orga-nized into four broad and overlapping developmental themes: cognitive, social, motor, and linguistic func-tioning. The skill areas are further divided into more specific skill goals, each related to one or more of the

325 developmentally sequenced learning activities

that make up the overall curriculum.31’32 The

educa-tional program was designed to emphasize

one-to-one positive interchanges between adults and

chil-dren rather than group activities, given the inherent

limitation on group functioning by very young

chil-dren.

Play Materials. Because toys are a typical means of

facilitating the young child’s learning, they were cho-sen carefully for the child development centers. Home

visitors also took toys to the homes in a specific

developmental sequence. A total of 1 7 toys, 7 in the

first year and 5 each in the second and third years,

were provided. The play materials component of the

intervention program was designed to encourage the

family to interact with the child through the

stimu-lating properties of developmentally appropriate,

at-tractive, and safe toys. Each of the first 1 2 toys was

accompanied by a guide book that the home visitor

discussed with parents, explaining a variety of ways

parents could use the toy and how and what the child

might learn by playing with it.

Monitoring Process

Home visitors and teachers extensively

docu-mented their contacts with IHDP parents and children

on standardized forms that were collected and

re-viewed weekly by the education director at each site.

These data were transmitted both electronically and

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460 INFANT HEALTH AND DEVELOPMENT PROGRAM

in hard copy to the Program Development Office

each week and checked for errors and inconsistencies.

Each form was read and checked by at least one, and

often two, research assistants. On a monthly basis

detailed summaries of program operation were

pro-duced for each program modality and content area.

Discrepancies in one area or for one site or staff

member could be readily noticed and attended to as

appropriate. In addition to the training sessions and site visits mentioned previously, 2 822 telephone calls

over 3 years between the Program Development

Of-fice and site staff were documented, most of which

were related to issues in program implementation.

This frequent and detailed monitoring and feedback

was implemented to increase the likelihood that the

eight sites delivered the same intervention. Summary of the Intervention Program

The early intervention model of the IHDP was

interdisciplinary, representing currently

recom-mended pediatric practices, family supports, and early

childhood education. The research program was

de-signed to test the efficacy of these combined program elements, not the relative contribution of individual

elements. The intervention was intensive and

con-ducted over a 3-year developmental period. The eight

sites had a specific protocol for program structure and content. Frequent monitoring and associated feedback encouraged adherence to the protocol.

Primary Outcome Measures

The IHDP intervention program was hypothesized

to have a positive impact on the child’s cognitive

development and behavioral competence at 3 years

of age, based on findings from two previous

interven-tion programs which served as the prototype for the

IHDP intervention program: the Carolina

Abecedar-ian Project35 and Project CARE.9 Cognitive outcome

was assessed by the Stanford-Binet Intelligence Scale, Form L-M, 3rd edition.36 The scale was administered

in a clinic by independent assessors who were

spe-cially trained and supervised by the National Study

Office at Stanford University and who were

unin-formed (‘blinded’) about the child’s treatment group

status. The National Study Office coordinated and

supervised all assessments, keeping the FPG staff and

all site intervention team members unaware of any

assessment outcomes until the study was completed. Mothers’ report of behavior problems was assessed

by the Child Behavior Checklist” at 36 months. These

data were collected by “blinded’ assessors who had

not administered the Stanford-Binet. The “Total

Prob-lem Raw Score’ was used for analyses, with higher

scores indicating more behavior problems.

Higher levels of IHDP participation were predicted to reflect higher rates and quality of child-care giver

transactions, which in turn would be associated with

intervention group children’s better cognitive and

social development compared with children who

ex-perienced lower levels of participation. Because the

initial status characteristics of birth weight, gender,

maternal education, maternal age, maternal race, and

neonatal health status are known to relate to

chil-dren’s cognitive performance, it is important to con-sider how these may relate to or possibly interact with

actual participation in predicting children’s outcomes at 3 years.

Program Functioning

RESULTS

Of the 377

infants and families who were randomly assigned to the intervention group, 371 received home

visits (98%); 325 attended the child development

centers (86%); and 294 families attended parent group

meetings (78%). Across the eight sites, a mean of 67

home visits were made to each child (median = 73)

during the 3 years of the intervention. Children

at-tended the child development centers a mean of 267

days (median = 326) and parents attended a mean of

3.7 parent groups (median = 3). The means and

standard deviations for participation in each program modality are presented for each site in Table 3 as well as the overall means, standard deviations, and ranges. There is considerable variability in family participa-tion in each modality within each site, including some families who participated actively in one modality but

refused to participate in another. However, despite

the demographic diversity across the eight sites, there is a basic consistency, on average, in the three partic-ipation indicators.

Creation of the Family Participation Index

We created a Family Participation Index by

sum-ming the number of home visits, attendance at parent

group meetings, and days attended at the child

de-velopment centers. This summative measure was

used because (1) the modality scores were selected at

the program’s inception to index family participation, as part of the monitoring process, and therefore were

defined before the outcome results were known; (2)

the three modality scores were only moderately

pos-itively correlated (.33 to .49, P < .001) and thus were not highly redundant; (3) each modality score loaded

moderately on the first component of a principal

components analysis (loadings = .37, .45, and .54 for

home visits, parent groups, child development center

days, respectively); (4) the program’s efficacy was

designed to be evaluated as the total impact of

com-bined modalities rather than as separable contribu-tions; and (5) frequency of contact is a practical metric

of measurement with relevance for other program

developers and for policymakers.

Figure 2 presents the means and standard errors of

the means for Family Participation Index scores for

each of the eight sites. The overall mean score on the

Family Participation Index was 337.7 program

con-tacts per family with a standard deviation of 166.9. Scores ranged from 0 to 552.

To assess the degree to which the Family

Partici-pation Index related to initial status characteristics, a multiple regression analysis was performed with birth weight, gender, neonatal health status, maternal race, maternal education, maternal age, and site as

predic-tor variables. Table 4 presents the results which,

surprisingly, revealed no significant effects associated

with a family’s participation for any of the initial

status characteristics.

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500

Mean Participatton index plus or rmnus

standard error of the mean

I

0

ARK EIN HAR MIA PEN TEX WAS YAL

(48) 46) (45) (44) (48) (49) (51) 46

Site

Fig 2. Mean Family Participation Index scores. Names of sites are

expanded in the first footnote to Table I.

Statistical Analysis Plan for Outcomes

Multiple linear regression models37 were fit to the

outcome variables to assess the significance of varia-lion in the Family Participation Index, while control-ling for effects of initial status variables on child

development. In was assumed that residual errors in

the Stanford-Binet at 36 months and the Achenbach

Problem Behavior Raw Score after adjustment are

approximately normally distributed random variables

with constant variance. The regression analyses were

restricted to children in the intervention group (n =

347 for Stanford-Binet and n = 338 for the Child

Behavior Checklist). To control for the effects due to the study design, site and birth weight were included in each regression model. In addition, five other initial

status variables were included: gender, maternal age,

maternal education, maternal race, and neonatal

health status.

Site was entered into each model as an eight-level categorical variable. It was decided a priori that birth

weight would be entered as a continuous measure,

providing adequate control for the design while

ena-bling inferences to be made concerning linear trends

TABLE 4. Regressio Variables (n = 377, R2 =

n of Participation Ind .0434)

ex on Initial Status

Model Parameter Estimate Standard Error

Degrees of Freedom

P

Value*

Intercept

Sex (female vs male) Race

305.476 -21.737

...

86.063 17.265

.. .

1

2 ...

.2088

.0997

Black vs other 38.553 22.797 1 .0917

Hispanic vs other

Birthweight,g

Maternal education

-18.034

0.011

11.937 35.074

0.020

9.415

1

1 .6074

.5835

.2056 (category)

Maternalage

Neonatal Health lndex

-2.816 0.023

1.723 0.561

1 1

.1031 .9673

Sitet ARK

...

63.948

...

35.472 7 1

.7562 .0723

EIN 26.768 37.830 1 .4797

HAR 42.369 35.302 1 .2309

MIA 50.444 38.316 1 .1888

PEN 27.646 37.767 1 .4646

TEX 30.232 37.050 1 .4150

WAS 45.383 34.239 1 .1859

YAL 0.000 ... ... ...

CProbability level for the test of the hypothesis that the effect is

equal to zero.

tSite effects are relative to Yale. Names of sites are expanded in the first footnote to Table I.

in the outcome variables with respect to birth weight.

Gender and maternal race were entered as two- and

three-level categorical variables, respectively, while

neonatal health status and maternal education were

entered as scaled measures. Maternal education

con-sisted of a five-category score ranging from: 1= ninth

grade or less; 2 = some high school; 3 = high school

graduate; 4 = some college; 5 = college degree or

more. A measure of neonatal health, the Neonatal

Health Index developed for this study, was based on

length of stay in the newborn nursery adjusted for

birth weight and standardized to a mean of 100.

Higher scores indicate better health.38 Differential effects were fit for the categorical variables with the

TABLE 3. Means and Standard Deviations of Participation Frequencies in Each of the Three Intervention Modalities From Hospital Discharge to 36 Months (Corrected Age)

. . Parent Group Child Development Home Visits

Meetings Center Days

Mean SD Mean SD Mean SD

ARK 66.2 23.9 4.5 3.5 298.8 160.0

(n=48)

EIN 69.5 15.8 3.1 2.5 243.2 129.5

(n = 46)

HAR 71.5 19.9 3.8 2.5 264.1 133.9

(n = 45)

MIA 76.7 20.0 4.3 3.4 278.3 131.7

(n= 44)

PEN 61.8 21.3 5.0 3.9 280.4 150.0

(n= 48)

TEX 59.5 21.8 3.0 2.7 275.8 139.6

(n= 49)

WAS 61.4 26.2 3.4 3.6 271.0 180.5

(n=51)

YAL 68.7 17.8 2.8 3.1 224.7 161.5

(n= 46)

Overall 66.7 21.6 3.7 3.3 267.3 150.0

(N = 377)

Range (0-100) (0-12) (0-468)

aNames of sites are expanded in the first footnote to Table 1.

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last level used as the reference level. For example, seven site effects were fit in each model, each equaling the difference in expected outcome for that site rela-tive to the eighth site, Yale. Overall multiple-degree-of-freedom tests are reported for categorical variables

as well as single-degree-of-freedom tests for each

effect associated with that variable. The test statistics

reported correspond to tests of the hypothesis that a

variable is associated with the outcome, conditional on adjustment for all remaining variables being in the model.

Regression models also were fit that included

inter-actions between the Family Participation Index and

each of the design and initial status variables. The

purpose of this analysis was to determine whether

the effect of participation varied across subgroups

defined by these variables. Predictor variables were

centered to a mean of zero to enhance interpretability of the results.

Program Participation and Cognitive Development

Table 5 presents results of the multiple regression analysis for the 36-month Stanford-Binet. This

analy-sis resulted in an R2 of .39 (F[15,329] = 13.8, P

.0001) and revealed that all variables except maternal age made significant incremental contributions to

pre-dicting cognitive development in the intervention

group. Significant findings (P .05) indicate that girls

performed better than did boys; children in the

‘other’ category (whites, Asians, and others)

per-formed better than did blacks or Hispanics; infants

with higher birth weights and with better Neonatal

Health Index scores performed better than did those

with lower birth weights or lower neonatal health

scores, and children whose mothers had more

edu-cation scored better than children whose mothers had

less education. Children at the Einstein and Miami

TABLE 5. Regression of Stanford-Binet IQ Scores at 36 Months

on Initial Status Variables and Participation Index (n = 347, R2 =

sites had lower cognitive scores than did those at the other six sites. Finally, more frequent participants

received significantly higher IQ scores than did less

frequent participants even after all other factors are taken into account.

To determine whether participation interacted with

other variables, a second regression analysis was con-ducted. No significant interactions were found.

Figure 3 provides a descriptive summary of

cogni-tive performance as a function of degree of partici-pation. Degree of participation was divided into high, medium, and low participation terciles. Each group’s

mean performance relative to the mean performance

of all follow-up children was plotted. The

interven-tion group performed better than did the pediatric

follow-up group and the degree of participation was

positively related to cognitive development.

That this sample was, indeed, at elevated risk for

poor cognitive development is evidenced by the low

overall mean performance of the pediatric follow-up

group (mean = 84.5, SD = 19.9), even when test

scores are corrected for prematurity. Thus, in the

natural ecology, the mean performance of premature

low birth weight infants is at the upper end of the

category labeled as “borderline intellectual

function-ing’ in the Diagnostic and Statistical Manual of Mental

Disorders of the American Psychiatric Association.39

The intervention group had average Stanford-Binet

IQ

scores of 93.5 (SD = 19.1), well within the normal

range.’2

A

way to consider the clinical relevance of the

overall average 9-point intervention vs pediatric fol-low-up group difference is to compare the percentage of children who scored in the borderline intellectual

functioning category (IQ between 71 and 85) or in

the mentally retarded range (IQ 70) as a function

of intensity of intervention. Figure 4 presents these percentages as a function of participation terciles and referenced to the performance of the pediatric follow-up group.

The percentage of children scoring in either of these clinical categories decreased with increased partici-pation. A Mantel-Haenszel

x2

statistic4#{176} was

com-puted, controlling for differences between sites and

birth weight groups. (This statistic provides an accu-rate measure of overall association, provided there is

no interaction between the controlling variables and

participation with respect to the probability of being at risk.) The stratified tables were examined to verify

0

.387)

Model Parameter Estimate Standard

Error

Degrees

of

P

Value* Freedom

Intercept

Sex (female vs male)

Race

53.007 5.186

. ..

8.349 1.674

...

. ..

1 2

...

.0021 .0001

Black vs other -12.910 2.213 1 .0001

Hispanicvsother Birth weight, g

Maternal education

-10.991 0.007

4.049

3.541 0.002

0.918

1 1

1

.0021 .0002

.0001 (per category)

Maternal age

Neonatal Health Index

0.038 0.125

0.167 0.054

1 1

.8189 .0210

Sitet

ARK

. ..

0.552

...

3.492

7 1

.0053 .8746

EIN -8.958 3.676 1 .0153

HAR -3.045 3.366 1 .3662

MIA -9.933 3.697 1 .0076

PEN 2.057 3.652 1 .5737

TEX -3.868 3.542 1 .2756

WAS -2.487 3.295 1 .4510

YAL 0.000 ... ... ...

Participation Index 0.029 0.006 1 .0001

Mean Parllcipalton indexplus orminus

standard error of the mean

Ijir

eProbability level for the test of the hypothesis that the effect is

equal to zero.

tSite effects are relative to Yale. Names of sites are expanded in

the first footnote to Table 1.

Pediatric Low IHDP Medium IHDP High IHDP

Follow.Up Participation Participation Participation

(n) (561) (97) (124) (126)

FoIlow.Up and Intervention Participation Groups

Fig 3. Mean Stanford-Binet IQ scores at age 3. IHDP, Infant Health and Development Program.

462 INFANT HEALTH AND DEVELOPMENT PROGRAM

110

100

F

90

80

70

60

(10)

40

30

-E

C’)

to<. t5

r. o <. 70

ARTICLES 463

20

j

Pediatric Low )HDP Medium )HDP High HOP

Fotlow.Up Participation Participation Participation

(n) (561) (97) (124) (126)

Foltow-Up and Intervention Participation Groups

Fig 4. Percentage of borderline (IQ 85) and retarded intellectual

performance (IQ 70). IHDP, Infant Health and Development

Program.

that this was indeed the case. The lack of evidence of interaction, in conjunction with the failure to detect a significant interaction of either site or birth weight with participation in the linear model fit to IQ, sup-ported the use of the summary

x2

test statistic for this analysis.

The probability of a child’s functioning in the bor-derline intellectual range or lower decreased signifi-cantly with increasing terciles of family participation: 19.6% of low participants, 1 1.9% of medium

partici-pants, and 6.9% of high participants

(x2

= 39.1, P

.001). In the pediatric follow-up group 35.5% scored

in the borderline intellectual range or lower. This

relationship also appears in the analysis of children

who score in the mentally retarded range (IQ 70):

13% of low participants, 3.5% of medium

partici-pants, and 1 .9% of high participants

(x2

= 54.6, P

.001). In contrast, 16.9% of the pediatric follow-up

group scored in the mentally retarded range at 36

months, compared with an estimated 1 % of the

gen-eral population.39 Thus, the “high participation”

in-tervention group is associated with an 8.9-fold

reduc-tion in the number of retarded LBW children at 3

years of age, when compared with children who

received only high-quality pediatric follow-up

serv-ices. The ratios for medium and low participation (4.9

and 1 .3, respectively) add support to the idea that

amount of participation in systematic, comprehensive early interventions is likely to be an important factor in accounting for individual differences in IQ among treated LBW, premature infants.

Program Participation and Behavior Problems

Table 6 reports results of the multiple regression

analysis using the Total Problem Raw Score from the

Behavior Problem Checklist as the criterion variable.” Although statistically significant (F[15,321] = 2.35, P

.003), the final model R2 was only .099 and the

only variable that was statistically significant was

maternal age, with younger mothers reporting more

child behavior problems than older mothers. No

lin-ear relationship was detected as a function of

partic-ipation, although there were fewer behavioral

prob-lems reported by mothers in the intervention group

than in the pediatric follow-up group (effect size =

-.18, P .001).2

Program Participation and Health

This study did not attempt to relate the degree of

program participation to health outcome because it

TABLE 6. Regression of Achenbach Total Problem Raw Scores at 36 Months on Initial Status Variables and Participation Index (n

= 338, R2 = .099)

Model Parameter Estimate Standard Degrees P

Error of Value5 Freedom

Intercept 64.299 10.310 ... ...

Sex (female vs male) -0.943 2.061 1 .6476

Race .. . . .. 2 .1467

Black vs other 1.610 2.766 1 .5610

Hispanic vs other 8.298 4.258 1 .0522

Birth weight, g -0.002 0.002 1 .3978

Maternal education -1.256 1.137 1 1.2703

(per category)

Maternal age -0.562 0.205 1 .0064

Neonatal Health Index 0.006 0.067 1 .9325

Sitet ... ... 7 .2466

ARK -2.557 4.364 1 .5583

EIN 4.206 4.576 1 .3588

HAR 0.871 4.288 1 .8391

MIA 4.790 4.657 1 .3045

PEN 1.783 4.574 1 .6969

TEX -2.424 4.434 1 .5850

WAS 6.259 4.141 1 .1316

YAL 0.000 . .. .. . ...

Participation Index -0.008 0.007 1 .2955

aProbability level for the test of the hypothesis that the effect is equal to zero.

t Site effects are relative to Yale. Names of sites are expanded in

the first footnote to Table 1.

was not feasible to obtain blinded data on health, and

differences between intervention and follow-up

groups were minimal. Of the six health outcomes

studied, only one differed significantly between

groups. There was a small increase in maternally

reported minor illnesses for the lighter-birth-weight group only.’2 However, we emphasize that in all eight

sites there were no serious infectious epidemics nor

serious accidents over a 2’/2-year period, thus indicat-ing the feasibility of a center-based intervention, even for this potentially vulnerable group.

DISCUSSION

The hypothesis that intensive early intervention

can improve cognitive development in LBW

prema-ture children is supported by increased IQ scores and decreased behavior problem scores in the intervention group relative to the pediatric follow-up group.’2 This conclusion is buttressed by the positive association

between degree of family participation in the

inter-vention program and child IQ at age 3 years. Despite this seemingly logical conclusion, and consistent with sampling theory, the possibility certainly exists that even after controlling for the initial status variables,

unidentified and unmeasured factors may better

ac-count for the systematic relationship between

partic-ipation and cognitive outcomes. The fact that these

initial status measures and participation measures

were selected before the experiment was begun and

that the analyses were specified before the data were examined increases the plausibility that the positive relationship between participation and cognitive out-come is not artifactual.

An additive model of influence concerning

varia-tions in initial risk status, degree of family participa-tion in intervention, and cognitive performance at age 3 appears to be a parsimonious model of development at Viet Nam:AAP Sponsored on September 1, 2020

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464 INFANT HEALTH AND DEVELOPMENT PROGRAM

under the condition of intensive family support. It

appears that intensive intervention increases cogni-tive performance but does not eliminate correlative

relationships between individual differences in

bio-logic, social, and psychologic risk factors. At a con-ceptual level, the multiple regression findings for IQ reinforce the practical utility of an integrated biosocial

and ecologic approach to understanding the early

development of LBW premature children. The results

clearly establish the necessity for prevention

pro-grams to consider potentially alterable factors in

bi-ology (eg, birth weight and neonatal health status)

and behavior (eg, maternal education and

interven-tion participation). The findings also indicate that

genetic and sociocultural contextual factors (eg, gen-der, ethnicity, and geographic site) exert additive

in-fluences on cognitive development, above and

be-yond effects associated with participation in intensive

early intervention. The long-term developmental and

intergenerational consequences of such alterable and

permanent factors need additional research to identify

the mechanisms through which such marker-level

variables exert their influence. A more precise

under-standing of basic developmental mechanisms, at both

the biologic and behavioral levels of analysis, may be a prerequisite for establishing early interventions that provide maximal effectiveness for risk populations.

The IHDP findings about variations in participation raise, but cannot adequately resolve, important

prac-tical questions about the intervention process. For

example, what are the precise determinants of

mdi-vidual differences in families’ participation? Our

anal-yses would suggest that they are not likely to be the

IHDP initial status variables or their correlates. This

is particularly important because comparable levels

of participation were achieved across eight diverse

geographic and sociodemographic sites. Nevertheless,

some families participated less than did others and

their children did less well on IQ tests. The bright spot in these findings is that high program

participa-tion can be achieved across diverse sites with all

ethnic and socioeconomic groups studied, and with

infants who varied dramatically in birth weight and

neonatal health.

The variation in participation rates is particularly perplexing given the high degree of initial acceptance

of the program by representative families of LBW

infants at each of the eight sites (76% overall). Given

the high initial acceptance of the program, and the

positive relationship between degree of participation

and child IQ, the understanding of factors leading to

low participation in such projects and what can be

done to increase participation by high-risk families is another important area for future research.

In a complex and, initially, expensive program, such as the IHDP, it is inevitable to wonder whether there

are particular components or combinations of

com-ponents that would be less costly and that could

achieve comparable effects. This question is important and empirically addressable but not within the IHDP,

which was designed to provide an efficacy test of an

intensive, integrated health and education program. For example, one component of many hospital-based early intervention programs, a parent program begin-ning during the infant’s early days in the neonatal

intensive care unit, was not included in the IHDP

model for logistic reasons. Would earlier support from a visitor have resulted in even greater effects? Ques-tions about the best timing or combinations of services have yet to be adequately answered.

Finally, why was the hypothesis concerning the

degree of family participation generally supported by

the IQ data but not by the behavior problem data?

Two hypotheses seem plausible. First the magnitude

of effect between intervention and follow-up on the

maternal report of behavioral problems was small

(effect size = -. 1 8), and therefore we may have

lacked sufficient statistical power to detect a system-atic participation relationship. Second, the overall

difference may have been small because the children

were not very much at risk for problem behaviors at

age 3, according to their mother’s report and,

there-fore, not much impact could be measured. This

hy-pothesis is supported by the fact that the mean scores

of both the intervention and follow-up groups are far

from the generally accepted clinical range (>63 and

do not, unlike the IQ data, indicate this to be a

developmental domain at particularly high risk at age

3. Additional analyses in the behavioral competence

domain using newly developed prosocial measures

are underway by another team of investigators and

perhaps those results will help to clarify the behavior problem findings.

In conclusion it appears that participation in inten-sive intervention services during the first 3 years of

life can have significant and positive effects on the

cognitive development of LBW, premature children.

How to ensure high participation of high-risk families

in high-quality programs is the task that must now

be addressed.

ACKNOWLEDGMENTS

The Infant Health and Development Program was funded by grants to the Department of Pediatrics, Stanford University; the Frank Porter Graham Child Development Center, University of

North Carolina at Chapel Hill; and the eight participating

univer-sities by The Robert Wood Johnson Foundation. Additional support

for the National Study Office was provided to the Department of Pediatrics, Stanford University, from the Pew Charitable Trusts; the Bureau of Maternal and Child Health and Resources Develop-ment, HRSA, Public Health Service, Department of Health and Human Services (grant MCJ-060515); and the Stanford Center for the Study of Families, Children, and Youth. Additional support to the Frank Porter Graham Child Development Center was provided by the National Institute of Child Health and Human Development and the state of North Carolina.

National Study Office: Ruth T. Gross, MD, Director; Donna

Spiker, PhD, Deputy Director; Norm A. Constantine, PhD, Director of Data Analysis; Wendy L. Kreitman, Director of Field Operations; Christine W. Haynes, Co-director of Field Operations (the Depart-ment of Pediatrics and the Center for the Study of Families, Children, and Youth, Stanford University).

Program Development and implementation Office: Craig T. Ramey,

PhD, Director; Donna Bryant, PhD, Associate Director; Joseph

Sparling, PhD, and Barbara H. Wasik, PhD, Co-directors of

Curric-ulum Development; Isabelle Lewis and Claudia Lyons, Curriculum Development Specialists; Kaye H. Fendt, MSPH, Director of Data Management and Statistical Computing (the Frank Porter Graham Child Development Center, University of North Carolina at Chapel Hill).

Participating Universities: University of Arkansas for Medical

Sciences (Arkansas); Albert Einstein College of Medicine (Einstein); Harvard Medical School (Harvard); University of Miami School of Medicine (Miami); University of Pennsylvania School of Medicine

(Pennsylvania); University of Texas Health Science Center at Dallas

(12)

(Texas); University of Washington School of Medicine (Washing-ton); Yale University School of Medicine (Yale).

Site Directors: Patrick H. Casey, MD, Arkansas; Cecelia M.

McCarton, MD, Einstein; Michael W. Yogman, MD, and Daniel Kindlon, PhD, Harvard; Charles R. Bauer, MD, and Keith C. Scott, PhD, Miami; Judith Bernbaum, MD, Pennsylvania; Jon E. Tyson,

MD, and Mark Swanson, MD, Texas; Clifford J. Sells, MD, and

Forrest C. Bennett, MD, Washington; David T. Scott, PhD, Yale.

Education Directors: Joan Rorex, MEd, Arkansas; Katy Lutzius,

MEd, Einstein; Marcia Hartley, MS. Harvard; Mimi Graham, PhD,

Miami; Joanne Crooms, MEd. Pennsylvania; Beverly A. Mulvihill,

PhD, Texas; Randi Shapiro, MEd, Washington; Sandra E.

Malm-quist, MA, Yale.

Bettye Caldwell, PhD, Educational Consultant, Arkansas; Ruth Turner, EdD, Dallas Independent School District Liaison, Texas;

Rebecca R. Fewell, PhD, Educational Consultant, Washington.

Research Steering Committee: Helena C. Kraemer, PhD, Chair

(Stanford); Charles R. Bauer, MD (Miami); J. Brooks-Gunn, PhD (Educational Testing Service, Princeton); Marie C. McCormick, MD (Harvard); Craig T. Ramey, PhD (North Carolina); David T. Scott, PhD (Yale); and Donna Spiker, PhD (Stanford); Research Associate; April A. Benasich, PhD Uohns Hopkins).

Sam Shapiro, Special Consultant to the National Study Office

and Ex-officio Member of the Research Steering Committee (The Johns Hopkins University School of Hygiene and Public Health).

Additional Contributors at the Program Development and

Imple-mentation Office: Marie Butts, Rhonda Hensley, Vickie Lindsey,

Steven Magers, Peggy Terry, Russell Vanneman, and Angela Wor-ley.

Special appreciation is extended to Sharon Landesman Ramey, PhD, for her enlightening insights, thoughtful editing, and con-structive criticism of numerous earlier drafts of this manuscript.

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2. Bennett FC. The effectiveness of early intervention for infants at

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