Measuring
developmental and
functional status in
children with
disabilities
Kenneth J Ottenbacher*PhD University of Texas Medical Branch, Galveston, Texas;
Michael E MsallMD, The Child Development Center, Providence, Rde Island;
Nancy LyonRN PNP, Robert Warner Rehabilitation Center; Linda C DuffyPhD, Children’s Hospital of Buffalo; Carl V GrangerMD;
Susan BraunMLS OTR; State University of New York; Buffalo, New York, USA.
*Correspondence to first author atUniversity of Texas Medical Branch, SAHS 4.202, 301 University Blvd, Galveston, TX 77555, USA.
This study compared performance on the Functional Independence Measure for Children (WeeFIMTM), the Battelle Developmental Inventory Screening Test (BDIST), and the Vineland Adaptive Behavior Scales (VABS) in children with developmental disabilities. The three
instruments were administered to 205 children with identified disabilities. All 205 children were tested using the WeeFIM instrument. The BDIST was administered to 101 children and the VABS to the remaining 104 children. Administration was counterbalanced and randomized across all three
instruments. A proportional sampling plan was used to select the 205 children, who ranged in age from 11 to 87 months. A variety of medical diagnoses and levels of severity of motor, cognitive, and communication impairments were
systematically included in the sample. Correlations (r) among subscales for all three instruments ranged from 0.42 to 0.92. Correlations for total scores ranged from 0.72 to 0.94. Analyses of potential moderator variables found no significant relation between age and severity of disability (r=0.05) or between socioeconomic status (SES) and severity of disability (r=0.21). Correlations with age were strongest for those subscale scores involving gross and fine motor skills. Correlations with SES and subscale scores ranged from 0.03 to 0.18. The three instruments provide important information regarding childhood performance in motor, self-care, communicative, cognitive, and social skills. The WeeFIM instrument requires less administration time and provides information directly relevant to evaluating functional outcomes for children with disabilities and their families.
The assessment of functional skills has been identified as a priority in early intervention and developmental research (Coster and Haley 1992, Butler 1995). Functionally based treatment and outcomes that focus on daily living skills are necessary for age-appropriate program planning, evalua-tion, documentaevalua-tion, and reimbursement in both clinical and educational environments (Garwood 1982, Haley et al. 1989, Butler 1995). There is also a need to identify assess-ments that are easy to administer; provide useful informa-tion to developmental specialists, parents, and teachers; and can be incorporated into the daily routine of busy health-care practitioners and educational professionals.
Functional assessment in children is described by McCabe and Granger (1990) as ‘an effort to systematically describe and measure a child’s abilities and limitations when perform-ing the activities of daily livperform-ing’ (p 121). Function is an impor-tant component of a comprehensive evaluation because it identifies what the child can accomplish in a specific environ-ment (Msall et al. 1994a, b). The advantages of functional assessment include: the consideration of special equipment or assistive devices in completing a task, and a focus on sup-ports necessary for success in the least restrictive community and educational environment. In addition, the task perfor-mance, not the process or method used to achieve the out-come, is emphasized. For instance, independent locomotion can be achieved via walking or using a wheelchair. The inabil-ity to walk produces a low score on a developmental evalua-tion, but not on an instrument assessing functional mobility, if the child is capable of using a wheelchair.
Two pediatric functional assessments currently exist for use with children: the Functional Independence Measure for Children (WeeFIM) (Guide 1993a) and the Pediatric Evaluation of Disability Inventory (PEDI) (Haley et al. 1992). Each instru-ment measures functional ability, taking into account the use of special equipment and amount of caregiver assistance. In con-trast to the 18 items of the WeeFIM instrument, the PEDI includes 73 Self-care items, 59 Mobility items, and 65 Social Function items (total 197). There is some overlap between WeeFIM assessment items and the PEDI Caregiver and Modifications scales. Table I compares the WeeFIM and several other commonly used pediatric assessments.
The WeeFIM instrument is designed to be administered by either direct observation or interview of a primary caregiver (parent, relative, teacher, or reliable respondent) who knows the child well. The goal of the WeeFIM instrument is to ‘measure changes in function over time to weigh the bur-den of care in terms of physical, technologic, and financial resources.’ (Braun and Granger 1991). Several investigators using the WeeFIM instrument have reported excellent con-sistency between ratings (ICC from 0.79 to 0.99) collected by direct observation and those obtained by interview of a pri-mary caregiver (Msall et al. 1993a, Sperle et al. 1997). The test–retest and interrater reliability of the WeeFIM have also been examined and found to be excellent with ICC values from 0.83 to 0.99 for subscale and total ratings (Msall et al. 1993a, Ottenbacher et al. 1996, Sperle et al. 1997).
The relation between functional assessment scales and traditional developmental evaluations of adaptive behavior has not been systematically examined. The purpose of this investigation was to compare the ratings obtained from the WeeFIM instrument with those from two widely used pedi-atric assessments: the Vineland Adaptive Behavior Scales
(VABS) (Sparrow et al. 1984) and the Battelle Developmental Inventory Screening Test (BDIST) (Newborg et al. 1984). Method
SUBJECTS
Health and disability characteristics
Two-hundred and five children receiving special services for identified developmental disabilities participated in the investigation. Their age ranged from 11 to 87 months (mean 45.77, SD 19.70). All children had a confirmed medical diag-nosis and were receiving treatment and/or developmental child support services in early intervention or school-based programs. The extent of disability ranged from mild impair-ment to severe multiple disability (see description below). A proportional sampling plan based on severity of disability,
type of disability, and age was used to ensure that children were evenly distributed. Etiology was determined by medical diagnosis. The most common medical conditions were cere-bral palsy, prematurity, Down syndrome, spina bifida, epilep-sy, and genetic impairments. Severity of disability was based on scores from standardized developmental assessments administered to the children to identify their original need for developmental and medical services. The instruments included the Bayley Scales of Mental and Motor Development (Bayley 1994), Clinical Adaptive Test/Clinical Linguistic Auditory Milestone Scale (CAT/CLAMS) (Hoon et al. 1993, Rossman et al. 1994, Wachtel et al. 1994) and McCarthy Scales (McCarthy 1972). At their initial entry into the medical service delivery system, the children were tested by licensed professionals with these instruments. Sixty-eight
Table I: Comparison of the Pediatric Evaluation of Disability Index (PEDI), Functional Independence Measure for Children (WeeFIM), Vineland Adaptive Behavior Scales (VABS), and Battelle Developmental Inventory Screening Test (BDIST)
PEDI WeeFIM BDIST VABS
Purpose Discriminative Evaluative measure Discriminative Discriminative measure of functional of performance of measure of measure of limitations in functional skills in developmental developmental children 6 mo to 7.5 y children 6 mo to 8 y skills in children skills for children birth to 8 y birth to 18 y Domains Motor Self-care Personal-social Communication Self-care Sphincter Transfers Adaptive Daily Living Social Locomotion Motor Socialization Communication Communication Motor Social Cognition Cognition
Standardization 412 non-disabled children 532 non-disabled children 800 non-disabled children 1200 children 0 to 71 mo 102 disabled children 500 disabled children 160 children with 1000 children 100 children in early handicapping with cognitive and intervention conditions 500 children with sensory disabilities Reliability Excellent test–retest Excellent test–retest Test–retest; and Split half for domains and interrater and interrater; interrater good- and composite, (ICC = 0.71 – 0.99) equivalence reliability excellent (r= 0.71 –1.00) excellent; of phone interview test–retest, (ICC = 0.73 – 0.99) excellent;
interrater, good (r= 0.62 – 0.98) Validity Concurrent with Concurrent with Concurrent with Concurrent with IQ Battelle and VABS, Battelle, and VABS and WISC-R and other adaptive WeeFIM WeeFIM (See Table II) (r= 0.70 – 0.90) measures (r= 0.81 – 0.93) (r= 0.73 – 0.96) Time to 45 min 20 min 35 min 45min
administer
Application Parent interview Measures of 3 to 7 y Normal and Preschool and format for children functional status of disabled long-term outcome with CP. Clinical VLBW cohorts in preschooler in EI. in VLBW children; evaluation after surfactant trials. Children with use in all rhizotomy and Functional goal developmental developmental traumatic brain setting in children disabilities in early disabilities
injury with CP, spina bifida, elementary school and genetic disabilities
children (32%) had standardized scores between –1.0 and –2.0 SDs below the mean (mild disability) on one or more of the instruments. One-hundred and four children (51%) had standardized developmental scores between –2.1 and –3.0 SDs (moderate disability), and 33 children (16%) had stan-dardized scores greater than –3.0 SDs below the mean (extreme disability).
Demographic characteristics
The majority of the children in the sample were white (70%). Twenty-one percent were African–American, 6% were Hispanic, and 3% were other. One-hundred and thirty-three were male and 72 were female. No predetermined method for division of male and female subjects was used as previous research on the WeeFIM did not indicate consistent signifi-cant performance differences between male and female
chil-dren with disabilities (Msall et al. 1993b, Msall et al. 1994b, Msall 1996). The final sample involved 71 children from 11 to 36 months of age, 81 children from 37 to 60 months, and 53 children from 61 to 87 months.
Information on socioeconomic status was collected. This was based on a compilation of demographic factors includ-ing educational level and occupation of parents, availability of transportation, use of paid outside help in the home, and presence of a telephone.
Recruitment
The sample was recruited from three early childhood educa-tional programs and developmental disabilities rehabilita-tion facilities in western New York. The three facilities served a population of approximately 1600 children and included follow-up clinical evaluation programs or educational day programs designed specifically for children with disabilities. Recruitment relied primarily on invitations by professional staff and teachers to parents of children with disabilities. Announcements were also made at participating facilities and posted in classrooms and meeting areas in the clinics and schools. Many of the children were in mainstream day programs, which also included children without disabilities. All three facilities involved integration of children without disabilities to some extent. Most of the children received related services as part of their Individualized Family Service Plans or Individualized Educational Programs.
Consent
The study protocol was reviewed and approved by the appro-priate institutional review boards. All participants provided written informed consent before completing the instruments. INSTRUMENTS
Functional Independence Measure for Children
The WeeFIM instrument is a pediatric functional assessment developed by health, rehabilitation, and child-development professionals (Guide 1993a, Msall et al. 1994). The WeeFIM is an adaptation of the Functional Independence Measure, designed to measure severity of disability in adults (Guide 1993b). The WeeFIM was developed to assess and track lev-els of functional independence in children aged 6 months to 7 years, across health, developmental, educational, and com-munity settings (Guide 1993a, Msall et al. 1994a). Key char-acteristics of the WeeFIM instrument are its minimal data set, emphasis on consistent actual performance, and its ability to be used by multiple disciplines (Guide 1993a, Msall et al. 1994a). The WeeFIM instrument contains 18 items divided into the following six areas: self-care, sphincter control, transfers, locomotion, communication, and social cognition. The motor subscale includes the areas of self-care, sphincter con-trol, transfer and locomotion, and contains 13 items. The remaining two areas (communication and social cognition) comprise the cognitive subscale. Each area consists of two to six items scored separately. A 7-level ordinal rating system ranging from 7 (complete independence) to 1 (total assis-tance) is used to rate each item. A rating of six means that the child can complete the activity independently, but requires either an assistive device or more than the usual amount of time, or that safety is a concern in completing the activity. A rating of five means the child requires a helper to supervise or set-up the task. A rating from four to one indicates that the Table II: Sample WeeFIM Rating Form. Adapted from the
Functional Independence Measure for Children (WeeFIM)
7 Complete independence (Timely, Safely) No helper 6 Modified independence (Device)
Modified dependence 5 Supervision
4 Minimal assistance (Subject=75%+)
3 Moderate assistance (Subject=50%+) Helper Complete dependence
2 Maximal assistance (Subject=25%+) 1 Total assistance (Subject=0%+)
Outpatient Self-care or follow up
A. Eating ———
B. Grooming ——— C. Bathing ——— D. Dressing – upper body ——— E. Dressing – lower body ——— F. Toileting ——— Sphincter control G. Bladder management ——— H. Bowel management ——— Transfers I. Chair/wheelchair ——— J. Toilet ——— K. Tub/shower ——— Locomotion L. Walk/wheelchair/crawl ——— M. Stairs ——— Communication N. Comprehension ——— O. Expression ——— Social cognition P. Social interaction ——— Q. Problem solving ——— R. Memory ——— Total WeeFIM ———
child requires some level of assistance from another person to complete the activity. For example, a rating of two indi-cates that the child is able to perform approximately 25% of the tack without assistance. Table II presents the WeeFIM items and rating protocol, including the percentage of the task completed by the child.
The WeeFIM instrument can be administered through direct observation, an interview, or both. Each item must be rated. No zeros or non-applicable ratings can be given. The minimum total rating is 18 (total dependence in all skills), and the maximum is 126 (complete independence in all skills). The WeeFIM instrument is designed to be discipline free. Training is recommended to ensure appropriate admin-istration and rating (see below) (Guide 1993a). Validity and interrater reliability have been examined in various studies and found to be adequate (McCabe and Granger 1990, Msall et al. 1993a, Msall et al. 1994b, Ottenbacher, Taylor et al. 1996, Sperle et al. 1997).
Battelle Developmental Inventory Screening Test
The original Battelle Developmental Inventory (BDI) (Newborg et al. 1984) assesses five domains of child develop-ment: personal-social, adaptive, motor, communication, and cognition. Although the BDI has a developmental frame-work, it samples functional content such as dressing, toilet-ing and mobility. In contrast to the WeeFIM instrument, the BDI examines the child’s skill level and does not include a scale that takes into account adaptive equipment or physical assistance. The BDI results in a total score as well as scores in each of the developmental areas. The test profile provides several different types of information: centile ranks, age equivalents, zscores, developmental quotients, tscores, and normal curve equivalents. The BDI is designed to assess the development of children from birth to 8 years of age. Information can be obtained from interviews with care-givers, observation, or structured assessment. Sexton et al. (1988) found that the data collected through interviews do not compromise the validity of the total score. The BDI pro-vides specific adaptations for children with visual, hearing, or motor disabilities.
The BDI includes a large item pool (341 test items) and takes 2 hours to complete. A modified version, the Battelle Developmental Inventory Screening Test (BDIST) has been developed (Glascoe and Byme 1993a) which consists of 96 items and can be administered in approximately 30 to 35 minutes (Glascoe and Byme 1993b). Feldman et al. (1990) reported that it is a strong predictor of performance on the BDI. The BDIST was used in this study.
The reliability and validity of the BDI and BDIST have been examined by several investigators (Guidibaldi and Perry 1984, Motts, 1987, Johnson et al. 1992, Glascoe and Byme 1993b) and reported to be adequate, with interrater and test–retest reliability ranging from r=0.71 to 1.00. Content validity (r=0.70 to 0.90) and concurrent validity have also been established (r=0.75 to 0.93) (Johnson et al. 1992, Glascoe and Byme 1993b).
Vineland Adaptive Behavior Scales
The Vineland Adaptive Behavior Scale (VABS) (Sparrow et al.1984) is designed to assess personal and social sufficiency of individuals with and without disabilities from birth to adulthood. The VABS is administered by a semistructured
interview with a caregiver or person who knows the client well. It measures adaptive behavior in four domains: com-munications, daily living skills, socialization, and motor skills. An optional domain of maladaptive behavior can be included. The VABS is designed to be administered by pro-fessionals with graduate degrees and specific experience in assessment of individuals and in test interpretation: a back-ground in human development and behavior, and in test construction and measurement, plus experience with devel-opmental disabilities is expected for proficient administra-tion of the VABS.
The standard version of the VABS consists of 301 items and takes 45 to 60 minutes to administer. There are five pos-sible ways each of the items on the standard VABS can be scored. The scoring options include the following: the activi-ty is never performed (zero points); the activiactivi-ty is sometimes performed or performed with partial success (one point); the activity is usually or habitually performed (two points); no opportunity to perform the activity (N); and the interview respondent has no knowledge of the client’s performance (DK, don’t know). Administration of the standard VABS results in a series of derived scores (converted raw scores that have uniform meaning from domain to domain and for all ages). The derived scores are based on the national stan-dardization sample and performance of supplementary norm groups (Sparrow et al. 1984). Derived scores obtained for each of the four adaptive behavior domains include stan-dard scores, bands of error, national centile ranks, stanines, and age equivalents (Sparrow et al. 1984).
Three forms of reliability have been reported for the VABS: internal consistency (split-half reliability), test–retest reliability, and interrater reliability (Rosenbaum et al. 1995, Vig and Jedrysek 1995). Internal consistency for the four domains ranged from 0.76 to 0.99 (Rosenbaum et al. 1995). Test–retest reliability for the four domains ranged from 0.76 to 0.93. The range of interrater reliability values for the VABS was 0.62 to 0.78 (Rosenbaum et al. 1995, Vig and Jedrysek 1995). With the exception of a moderate interrater reliability correlation of 0.62 for the domain of socialization, the over-all reliability of the VABS is considered good for an interview instrument (Raggio et al.1994).
The construct validity of the VABS has been examined by investigating the profiles of persons with and without identi-fied disabilities. Factor analytic studies have also been con-ducted to examine construct validity (Raggio et al. 1994). Concurrent validity studies have been conducted using intel-ligence and achievement tests. High correlations have been found between these tests and the domain of communica-tion on the VABS (Raggio et al.1994).
PROCEDURE
A trained rater with a background in rehabilitation and developmental disabilities initially interviewed caregivers in the facility where the child received intervention or follow-up services. The purpose of the study was explained and each caregiver was provided with an information sheet. In cases where a parent was not available, the assessment was administered to a caregiver designated by the parent as being familiar with the child’s functional abilities. In all cases where the parent was not available, the interview was completed with the child’s teacher. Before the interview with the child’s caregiver, the interviewer was not aware of
the child’s medical history or disability.
The assessments were administered according to the established protocol for each instrument. The WeeFIM was administered to all 205 children. The BDIST was adminis-tered to 101 children and the VABS to the remaining 104 chil-dren. Whether a specific child was assessed using the BDIST or the VABS was determined by a random process (coin flip). The order of the administration was alternated so that approximately half of the children were administered the WeeFIM first. The two test administrations occurred within a period of 3 weeks.
Raters were blind to the child’s health status and previous scores on developmental tests before the initial assessment. The date and time of all assessments were recorded and every effort made to schedule the second assessment on the same day of the week and at approximately the same time as
the initial assessment. The same person (parent or teacher) interviewed initially was also interviewed during the second assessment.
Raters
The primary rater who collected the majority of the data obtained using the WeeFIM instrument, and all the BDIST and VABS information, for the 205 children was a pediatric nurse practitioner with more than 20 years’ experience in develop-mental disabilities and rehabilitation. All other raters collect-ing information uscollect-ing the WeeFIM instrument were health, developmental, or rehabilitation professionals with at least 3 years’ experience working with children with disabilities and their families. Each rater completed training in the administra-tion of the WeeFIM that included review of the WeeFIM admin-istration and rating protocol, viewing a 25-minute training
Table III: Means, SD, and correlations for the WeeFIM instrument, Battelle Developmental Inventory Screening test (N=101), and the Vineland Adaptive Behavior Scales (N=104)
Subscales WeeFIM instrument domains
Self-care Sphincter Transfer Locomotion Communication Social Cognition Total 17.34 (mean) 6.00 13.56 10.63 6.74 9.15 62.39 9.12 (SD) 5.32 7.56 4.82 3.47 4.37 27.38 Battelle Personal 0.82 0.72 0.76 0.62 0.84 0.78 0.85 20.73 (mean) 9.32 (SD) Adaptive 0.92 0.85 0.86 0.75 0.65 0.78 0.94 18.27 9.36 Motor 0.88 0.79 0.86 0.80 0.76 0.73 0.91 17.65 8.64 Communication 0.80 0.72 0.73 0.62 0.86 0.75 0.84 15.32 7.39 Cognitive 0.79 0.72 0.73 0.59 0.85 0.75 0.83 15.63 8.42 Total 0.89 0.80 0.83 0.70 0.86 0.80 0.92 86.43 38.54
Subscales WeeFIM instrument domains
Self-care Sphincter Transfer Locomotion Communication Social Cognition Total 17.63 (mean) 6.54 13.33 11.47 6.03 9.15 62.31 8.18 (SD) 5.12 6.38 4.83 3.24 4.39 24.26 Vineland Communication 0.70 0.51 0.48 0.42 0.86 0.79 0.72 48.35 (mean) 28.74 (SD) Daily Living 0.88 0.70 0.71 0.58 0.81 0.73 0.91 41.10 23.52 Social 0.71 0.54 0.50 0.40 0.86 0.77 0.74 47.06 15.43 Motor 0.80 0.65 0.83 0.77 0.61 0.53 0.87 40.83 17.54 Total 0.86 0.72 0.77 0.68 0.82 0.70 0.89 206.32 56.75
videotape (Msall et al. 1990), and rating two case studies to cri-terion standards. The case studies included written informa-tion describing a child with a disability. Successful compleinforma-tion of the training required 90% agreement with the case-study material. If a rater did not achieve the 90% criterion on the first assessment following training, the protocol was repeated. Each rater administered a minimum of two ‘pilot’ WeeFIM assessments to establish the interview format.
Results
Spearman correlation coefficients (r) for the various sub-scales and total score comparisons between the WeeFIM instrument and the BDIST, and the WeeFIM instrument and the VABS are included in Table III. Table III shows that the cor-relation values for area ratings ranged from 0.42 to 0.92. Four of the 36 correlations between the WeeFIM instrument and BDIST were <0.70. Several major patterns exist between the BDIST domains and WeeFIM domains and WeeFIM total scores. The BDIST person/social domain is significantly cor-related with WeeFIM self-care, and communication scales, and with total WeeFIM ratings (r>0.80). The BDIST adaptive domain is significantly correlated (r>0.80) with WeeFIM self-care, sphincter, and transfers scales, and with total WeeFIM ratings. The BDIST motor domain is significantly correlated with WeeFIM self-care (r=0.08), transfers (r=0.86), and loco-motion (r=0.80) scales, and with total WeeFIM ratings (r=0.91). The BDIST communication domain is significantly correlated (r>0.80) with WeeFIM self-care and communica-tion scales, and with total WeeFIM ratings . The BDIST cogni-tive domain is significantly correlated (r>0.80) with WeeFIM communication and total WeeFIM ratings .
Nine of the 20 correlations between the WeeFIM and VABS domains were below 0.70. Several major patterns were
noted between the VABS and WeeFIM domains and WeeFIM total ratings. The VABS Communication domain is robustly correlated (r=0.86) with WeeFIM communication ratings. The VABS Daily Living Skills domain is strongly correlated (r>0.80) with WeeFIM self-care and communication domain and with WeeFIM total ratings. The VABS Socialization domain is highly correlated (r=0.86) with the WeeFIM com-munication domain, and moderately correlated (r=0.77) with the WeeFIM social cognition domain . The VABS motor domain is significantly correlated (r>0.80) with the WeeFIM self-care and transfer domains, and with total WeeFIM ratings. None of the correlations involving total scores for the three instruments was <0.70. All correlations for total scores were statistically significant (P<0.05). In general, the corre-lations for the WeeFIM instrument and BDIST were stronger than for the WeeFIM instrument and the VABS (see Table III). The correlation value for total ratings between the WeeFIM and the BDIST was 0.92. For the WeeFIM and the VABS, the correlation between total ratings was 0.89. Table IV includes the intercorrelations for the subscales for each of the three instruments. Examination of Table IV reveals that the sub-scales for the BDIST are more highly correlated with each other than are subscales for the WeeFIM or VABS. The high intercorrelations (r>0.90) for some subscales in the BDIST suggests that these subscales are measuring similar attribut-es in the children included in this sample.
The results of subanalyses for potential moderator vari-ables indicated no statistically significant correlation between age and severity of disability (r=0.05) or between SES and severity of disability (r=0.21). As expected, substan-tial correlations existed between age and the various sub-scale and total scores across all instruments. Correlations with age were generally strongest for those subscale scores
Table IV: Intercorrelations among subscales for each of the three instruments
WeeFIM instrument
Self-care Sphincter Transfer Locomotion Communication Social cognition Self-care – Sphincter 0.78 – Transfer 0.71 0.69 – Locomotion 0.61 0.64 0.78 – Communication 0.65 0.67 0.47 0.60 – Social Cognition 0.61 0.41 0.42 0.38 0.79 — Total 0.97 0.84 0.94 0.82 0.82 0.81 BDIST (Battelle)
Personal Adaptive Motor Communication Cognitive Personal – Adaptive 0.87 – Motor 0.83 0.92 – Communication 0.92 0.86 0.84 – Cognitive 0.91 0.85 0.82 0.93 – Total 0.95 0.95 0.92 0.95 0.94 VABS (Vineland)
Communication Daily Living Social Motor Communication –
Daily Living 0.86 –
Social 0.91 0.87 –
Motor 0.66 0.85 0.68 – Total 0.90 0.88 0.84 0.89
involving fine or gross motor skills. For example, the correla-tion between age and the BDIST gross motor score was 0.75 and for the fine motor score of the BDIST the correlation with age was 0.79. Correlations with SES and subscale or total scores were statistically insignificant and ranged from 0.03 to 0.18.
The relations between WeeFIM instrument and the BDIST and the WeeFIM instrument and the VABS were graphically examined by computing scatter plots for the total scores. The raw scores for all instruments were used to compute the total scores. The scatter plots (Figs 1 and 2) reveal a linear rela-tion. There is evidence of floor effects in both figures, sug-gesting that a disproportionate number of children score at the lower end of the scale. The low scores are correlated with the ages of the children: younger children who have not yet developed higher-level functional skills tend to score at the low end of the rating scale. Previous research has demon-strated that despite the restricted range of ratings for younger children, the reliability of the WeeFIM instrument is good (ICC 0.85 to 0.95) (Ottenbacher et al. 1997).
Discussion
The purpose of this investigation was to compare perfor-mance of children with developmental disabilities on the WeeFIM instrument, the BDIST and the VABS. The results suggest that the three instruments produce ratings that are similar in several areas, but distinct in others. The correlation values for WeeFIM total scores and BDIST subscale scores were strong, ranging from 0.83 for the cognitive subscale to 0.94 for the adaptive behavior subscale. The correlations with WeeFIM total ratings and subscale scores for the VABS ranged from 0.72 for communication to 0.91 for daily living skills.
The results suggest that the WeeFIM instrument, BDIST and the VABS are measuring similar skill areas. Whether
spe-cific skills are subsets of the same construct is not clear from the information collected in this investigation. This study was not designed to be an assessment of the construct validi-ty of the WeeFIM instrument. The WeeFIM is designed to assess the construct of functional independence in children and is based on the conceptual framework of the World Health Organization’s International Classification of Impairments, Disabilities, and Handicaps (ICIDH) (WHO 1980). The ICIDH forms the conceptual foundation of nei-ther the Battelle Developmental Inventory Screening Test nor the VABS. The important issue of construct validity of the instruments included in this investigation is complex and beyond the scope of this investigation. An examination of construct validity would involve a comprehensive factor analysis of the combined items for all three instruments (Portney and Watkins 1993). Such an investigation would also require an evaluation of the theoretical and conceptual distinction between developmental assessment and func-tional independence.
There are several practical implications contained in the results of this investigation. First, there is the obvious differ-ence in time, effort and training required to collect informa-tion from each of the instruments. The WeeFIM instrument can be completed in approximately 15 minutes by a trained examiner. In contrast, the VABS takes approximately 1 hour to administer and the examiner is expected to have a gradu-ate degree and considerable experience in the assessment of children. The BDIST takes approximately 30 minutes to administer. McLean and McCormick (1993) have identified several limitations of the BDI and BDIST, including the need to administer each item in a specific order. This requirement restricts the flexibility of the BDI and BDIST, particularly in use with young children.
It should be noted that the WeeFIM instrument is not
Figure 1:Scatter plot of total WeeFIM ratings and Battelle Developmental Inventory Screening Test scores for 101 children with disabilities.
Figure 2:Scatter plot of total WeeFIM ratings and Vineland Adaptive Behavior Scales scores for 104 children with disabilities.
meant to replace more comprehensive assessments such as the VABS, BDI, or PEDI. The results of this investigation, nonetheless, suggest that similar basic information can be obtained from the WeeFIM instrument, although it will be less than that provided by more comprehensive assessments. The second practical implication of the findings concerns the value of the information as perceived by rehabilitation professionals, educators, developmental clinicians, parents, and policy makers. There is a tendency, particularly in educa-tional settings, to emphasize funceduca-tional skills used in daily living as goals in program planning. Frequently there is dis-agreement between medical or rehabilitation professionals and educators in approaches to assessment and program planning. Medical professionals have traditionally per-formed assessments focusing on underlying physical or neu-rological impairment or etiology. Educators are generally less interested in underlying etiology and more concerned with practical limitations related to classroom performance. The results of the current investigation suggest that informa-tion collected from a developmental instrument used widely by clinicians, that is, the BDIST, is very similar to data provid-ed by an assessment that focuses on functional indepen-dence. This information may help to reduce some of the tension that frequently exists between medical or rehabilita-tion professionals and educators. The WeeFIM instrument provides results that are similar to those contained in a devel-opmental assessment (BDIST), but presents the findings in the context of functional skills acceptable to educators and relevant to parents and other family members (for example, toileting and dressing. Information on functional outcomes is also of value to educators and parents in documenting change over time or planning intervention programs).
An additional feature of the WeeFIM not associated with developmental instruments is the emerging pediatric dis-abilities database that is maintained by the Uniform Data System for Medical Rehabilitation (UDSMR). Facilities using the WeeFIM instrument and meeting certain credentialing criteria submit data from the WeeFIM instrument to the UDSMRfor compilation in a national database. Currently the database contains approximately 5000 records including WeeFIM ratings and related demographic, financial, and diagnostic information. The research potential of this data-base has not been explored but holds considerable promise for systematically describing the emergence of functional independence in children with various types of disabilities.
The WeeFIM instrument is a new pediatric assessment and additional research is required to refine its validity, reliability, and responsiveness. A replication of this study using other developmental instruments will help to identify further the unique contributions of the WeeFIM instrument to pediatric assessment. Another area of future research involves the impact of training on WeeFIM administration and scoring. The influence of different professional backgrounds (for example, educators, physicians, developmental therapists, pediatric nurse clinicians, psychologists) in administering, rating, and interpreting the WeeFIM instrument is not well understood. There may, for example, be variations in how different professional disciplines observe and rate selected items. Future research will provide the information neces-sary to establish functional assessment as a regular part of the evaluation process for children with disabilities and to help families identify goals to enhance functional independence.
Accepted for publication 5th August 1998. Acknowledgement
This research was supported by a grant from the DHHS, Health Resources and Services Administration, Maternal and Child Health Bureau (MCJ-360646). We appreciate the assistance of Lucy Phillips, Barbara J Hard, Nancy Heyer, and Shoou-Juin Wang in the collection and analysis of data.
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