Prediction of Hospitalization During Infancy: Scoring the Risk of Admission

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Prediction

of Hospitalization

During

Infancy:

Scoring

the Risk of Admission

S. T. Winter, M.D., and Pearl Lilos, B.Sc.

From the Pediatric Department, Rothschild Hospital and The Aba Khoushy School

of Medicine, Haifa, Israel

ABSTRACT. A cohort of 5,243 live newborn infants in

Haifa was followed to determine hospital admissions during the first two years of life. Parameters of the family and the

neonate, routinely available at birth, were collected and studied in order to select those which would identify co-host infants with an increased risk of hospitalization

dur-ing infancy. A total of 767 cohort children (14.6%) were admitted to hospital.

Multivariate analysis showed that many group factors

are interrelated and therefore inconsistent. Six single in-dependent factors predisposing to hospital admission could be defined (in order of decreasing significance) :

increas-ing birth order, male sex, poor education (up to four

years of schooling), birth weight less than 2,250 gm,

Jewish mothers born in Asia or Africa, and maternal age up to 24 years.

Numerical risk coefficients allocated to each of the above

six single (multivariate) factors enabled the calculation of a predicted risk coefficient scoring the risk of admission to hospital. The use of a score predicted 43.3% of the total initial hospitalizations affecting 23.3% of the total cohort.

The allocation of health resources might be improved by the use of such a method of scoring to select families in need of special services. Pediatrics, 53:716, 1974,

HOS-PITALIZATION, RISK PREDICTION, RECORD LINKAGE.

Many admissions of children to hospital are de-termined by social and other reasons rather than

by predominantly medical ones. A useful approach to reducing hospitalization might be the early recognition within a community of those infants with a special likelihood of being admitted to hos-pital during infancy. Selective allocation of child health services to such defined “special risk” groups might then attempt to modify the pattern of

hos-pital admission.

In this study, a large cohort of live newborn in-fants, upon whom data were collected at the time of birth, was followed to determine hospital ad-missions during the first two years of life. The

pur-pose of this inquiry was to seek parameters of fam-ily and neonate, routinely available at birth, which

would identify those infants with an increased risk of hospitalization during infancy.

MATERIALS AND METHODS

Over 99% of births in the Haifa region take place

in hospital. Children are admitted to one of two public hospitals in Haifa (Rothschild Hospital or Rambam Hospital) without restriction.

A

cohort

of 5,243 newborn infants was born in

three cooperating Haifa maternity departments from

January 1, 1965, until November 4, 1966. The co-hort was unselected but was neither complete nor consecutive. It represented approximately 56% of the total births to Haifa mothers in these maternity units during the study period. The majority of

omissions were due to lack of registration of

new-borns through random staff duty problems.

De-liberate exclusions included infants of very low birth weight or with severe birth injury or malfor-mations considered by the neonatologist in direct charge to have poor prospects of survival in the newborn nurseries, the few infants considered for adoption, and those whose residence permitted their possible admissions to hospitals outside Haifa. The aim was to assemble a cohort of infants leaving newborn nurseries with good prospects of surviving infancy and receiving standard medical supervision.

Characteristics of the cohort were compared with selected data on births in Israel and in Jerusalem.’

Data on

the

cohort, collected from the birth

(Received July 20; revision accepted for publication

No-vember 29, 1973.)

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TABLE I

DATA ASSEMBLED FOR EACH COIJ0RI’ NEWBORN

certificates and obstetric records, included items

recorded in Table I.

Admiion to hospital of cohort infants during

their first two years of life were sought by weekly inspection of all the admission records of the Roths-child and Rambam hospitals between 1965 and 1968. The hospital case sheets of all cohort ad-missions were then reviewed by the senior author

(

S.T.W. ) together with a second physician. Stan-dard diagnoses, independent of the written hospital diagnoses, were made on the basis of the hospital data. All death certificates of Haifa children up to the age of 2 years were reviewed to ascertain cohort deaths outside hospital.

Data from the birth certificate and obstetric record of each cohort infant and from each hos-pitalization record were coded and punched on IBM cards.

Statistical methods included multivariate

analy-sis, as developed for the study of perinatal

mor-ty3 in order to isolate and assess the uncon-founded effect of individual factors, since single-parameter investigations consider interrelated vari-ables.

RESULTS

Selected characteristics of the cohort of 5,243

children, along with those of consecutive unselected Jerusalem live births during 1966, are shown in Table II. More details of the cohort analyses and other births in Israel, along with data on the hos-pital admissions (patterns of disease, principal single reasons for admission, hemoglobin and body

weight values) are noted elsewhere.’ During the first two years of life, 767 cohort children ( 14.6%)

were admitted to hospital a total of 1,078 times: 585 single admissions and 182 children with mul-tiple admissions (times admitted: X 2, 117

chil-ren; X 3, 38; X 4, 16; X 5, 4; X 6, 2; X 7, 3; x 8, 1; and X 20, 1 child).

The ages of the 767 children at the initial

ad-mission were as follows : up to 1 month, 44 children; 1 to 2 months, 65; 2 to 3 months, 46; 3 to 6 months, 166; 6 to 9 months, 124; 9 to 12 months, 89; 12 to

18 months, 159; 18 to 24 months, 74 children.

Group Attributes Predisposing to

Hospitalization

The unstandardized individual factors are noted in Table III.

Single Factors Predisposing to Hospitalization (Multivariate Analysis) In order to study the effects of the above group attributes taken independently, multivariate analy-sis of the separate items was performed, based on

the 767 children admitted, whether or not

subse-Newborn: Sex, birth weight, multiple births, date of birth

Each

Parent:

Country of birth, religion, years in Israel, years of schooling, years of marriage, age, occupation, number of liveborn children from marriage, consanguinity, residence

Mother: First or other marriage, birth order (parity), total number of liveborn children (including previ-ous marriages), number of children born dead, number of children who died

quenfly readmitted. Twelve parameters were

ana-lyzed: sex and birth weight of infant; mother’s age,

country of origin, years of schooling, parity,

de-ceased liveborn children, stillbirths; parental con-sanguiity; year and month of birth; place of

resi-dence.’

The following six single factors, predisposing in-dependently to admission, were significant (in or-der of decreasing importance) : ( 1 ) parity (birth

order), increasing (p < .001) ; (2) sex, male (p

< .001) ; (3) (4) mother’s years of schooling, four or less or “not stated,” and infant’s birth weight, less than 2,250 gm (p < .001) ; (5) mother’s country of

origin, born in Asia or Africa (p < .001 ); and (6) mother’s age, up to 24 years (p .001).

Parental consanguinity, year and month of birth, and place of residence were not significant factors.

TABLE II

SELECTED CHARACTERISTICS OF HAIFA AND JERUSALEM BIRTHS

Jerusalem Haifa

Cohort

Lire births

1 ‘)66

No. of Births 5,243

C (

5,800

C (

Mother-Age Less than 21) 4.4 5.1

Over 39 2.7 :Lt,

Mother-Years 0-4 21.1 19.4

of schooling 1 3 and over I2.9 6.2

Not stated 7.8 9.7

Birth order 1-2 58.7 50.3

5 and over 15.5 25.8

Mother-Country Israel (Jew) 24.1 35.7

oforigin .\sia 15.8 25.1

Africa 29.1 23.3

Europe-America 25.3 12.9

Non-Jews 5.6 3.0

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6 Parameters

Positive Negative .20

.03

.05

.04 .04 .02 .10

GROUP ATTRIBUTES PREDISPOSING TO HOSPITALIZATION +0.38

The estimated incidence of hospitalization in such an example is 38%, with individual chances of hos-pitalization of about one in three.

This concept of scoring was tested by applying risk coefficients of the six parameters to all the co-hort children and comparing the actual hospitaliza-tion rates of groups with different total risk co-efflicents. The predicted risk of all the cohort chil-dren is shown in Table V.

It is clear that there is a highly significant trend for children with a high predicted risk coefficient to be hospitalized than those with a lower

coeffi-Thus the concept of a realistic hospitalization risk coefficient is practicable. Concentration of

pre-ventive activities on the 1,222 children, out of the total cohort of 5,243, with a risk coefficient of 0.20 and over, would probably affect 332 children (23.3%

of the total cohort) who represent 43.3% of the

Increasing parity Male sex of infant

Less education of each parent (years of schooling)

Decreasing birth weight under 2,250 gm Mother (Jewish) born in Asia or Africa Non-Jewish mothers

Mother aged more than 39 years Father aged less than 20 years

Mother immigrating to Israel 8 to the birth of the cohort infant Increasing length of marriage Second or later marriage

Increasing number of liveborn children

Increasing number of deceased children

Increasing number of stillbirths Parental consanguinity

Jews residing in rural settlements Non-Jews residing in Haifa

Non-Jews

The large numbers of mothers with inadequate in-formation on stillbirths and deceased liveborn chil-dren reduced the value of significance tests on these two parameters.

Multivariate analysis of these six significant fac-tors yielded separate risk coefficients, noted in Table IV. The total effect of all six parameters explains only part of the total risk and leaves an overall residual risk. This residual is 0.20, if all the

other factors can be excluded. This, being relative-ly large, is due to other unidentified factors, and is independent of the known parameters.

Scoring the Risk of Hospitalization

Prediction of the risk of hospitalization was tried by applying the six studied risk factors (Table IV). The positive or negative risk coefficients are added

to the overall risk coefficient. This may be illus-trated by taking, as an example, a Jewish woman, aged 34 years, born in Morocco, three years’ school-ing, birth order 6, male infant weighing 2,100 gm at birth.

The score of the risk of admission would be calculated as follows:

For

Overall effect

Country of origin

Age of mother

Years of schooling Birth order

Male infant Birth weight

cient.

+.43 -.05

initial hospitalizations. Such an approach might

represent a significant gain in efficient allocation

of health services.

DISCUSSION

There have been few studies of the incidence

of hospital admissions among defined groups of

children, and apparently no available prospective

study aimed at predicting the risk of hospitalization.

The national sample survey of Great Britain4 showed a clear social class gradient, large families and overcrowding related to admissions for

infec-tions. Maternal competence, but not the

socio-economic status of the family, showed a correlation with the probability of hospital admission among the thousand families studied in

Newcastle-upon-Tyne.5 The low birth weight was considered of

major importance in the higher rate of

hospitaliza-tion of premature infants studied by Drillien.#{176} Difficult social conditions in Finland7 and Den-mark8 were significant factors in increasing the

ad-mission rate, these including bad housing, mother’s work outside the home, family illness and, less commonly, maternal incapacity. An unusual aspect of another study in Finland9 was that the admission

rate was greater among families with one child,

diminishing steadily with family size up to the

families with six children, and then rising again. The initial Paris study by Straus et al.1#{176}showed that group factors predisposing to hospitalization included the fact that the referring doctor was one casually consulted rather than the regular family doctor, the number of available hospital beds, housing conditions, the father’s low income, the mother’s employment outside the home, combined with a large number of children. At a subsequent

TABLE III

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TABLE IV

RISK COEFFICIENTS OF HOSPITALIZATION

Parameter

Coefficient Based on

6 Parameters

Positive Negati re

Total effect (Residual

overall risk) .20

Sex Mak .02

Female .02

Age of mother (yr) Less than 20 .05

20-24 .02

25-39 .05

Over 39 .01

Birth weight (gm) Less than 2,250 .10

2,250-2,499 .02

3,000-3,999 .04

4,000 and over .04

Mother Israel .01

Country of Asia .03

origin Africa .03

Europe-America .02

Non-Jews .04

Mother 0-4 .04

Years of 5-8 .01

schooling 9-12 .03

I 3 and more .05

Not stated .06

Parity 1 .08

2 .03

3 .03

4 .01

5-6 .04

7 and more .08 Not stated .02

European seminar on hospitalization of children,11 reports from various French cities, Belgium and

Greece commented on multiple contributory

fac-tors. These included the nationality and vocation

of the parents, parental anxiety and “faults” of the child’s doctor ( “busy” or “lazy”) . Many children

were brought to hospital without a doctor’s referral,

TABLE V

PREDICTED RISK COEFFICIENTS OF ALL COHORT CHILDREN AND ACTUAL ADMISSIONS

Predicted Risk

Coefficient

.J’io.of Children

--Hospitalized Jiot

Ho3pital-z:ed

Total .rio.

Less than 0.10 132 7.9 1,547 1,679

0.10-0.19 303 12.9 2,039 2,342

0.20-0.29 249 24.3 775 1,024

0.30andover 83 41.9 115 198

Total 767 14.6 4,476 5,243

and many admissions were not justified on strictly medical grounds.

A birth weight of less than 2,490 gm and a low

maternal age were significant characteristics

in-fluencing subsequent hospital morbidity of the baby

in the Oxford Record Linkage Study.12 The pres-sure of overanxious parents and the professional

and personal faults of the referring physician were

major reasons for unnecessary hospital admissions in Belfast.13

Previous Haifa studies showed that

hospitaliza-tion of infants was more common in families from

poorer areas of the town, in Oriental families, for males, for low birth weight infants and during the first six months of if516

The present study did not investigate factors

requiring special observation such as maternal

ca-pacity, parental anxiety, father’s income or mother’s

work outside the home. It confirmed the importance of parental age and education, place of residence and neighborhood, size of family and birth weight. It however added further parameters, including sex of infant, years of marriage, first or other marriage,

number of deceased liveborn infants, stillbirths, consanguinity, years of immigration and season of year.

Multivariate analysis seeking single factors

showed that, in order of decreasing significance, increasing birth order, male sex, birth weight less than 2,250 gm and low maternal education, mother

born in Asia or Africa and maternal age less than

25 years are highly significant factors in determining

the risk of admission to hospital. The other factors noted in the group attributes were not shown to

be significant, and some of these are probably re-lated to the above-mentioned significant single

fac-tors. Thus, inconsistencies and the unreliability of interrelated group attributes were demonstrated.

Birth order may exert its influence as a

predis-posing factor through the overcrowding of larger

families under unsatisfactory conditions, a trial of maternal competence and a tendency of respiratory tract infections. The factor of the male sex has received inadequate attention in the allocation of health services.’6 The level of education of parents influences their understanding of health, disease and guidance, and may modify harmful traditional

practices. The continuing development of

educa-tion for all sects in Israel offers prospects for

re-duced morbidity and hospitalization. Low birth weight is associated with an increased

susqepti-bility to illness, especially infections, increased he-quency of congenital malformations, anemia and parental anxiety. The country of origin, as a slhgle factor, may act in that the predisposition to hos-pitalization is related to parental attitudes to health

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a new and generally more sophisticated society.17 Whereas the general impression is that it is the older harassed mother who tends to bring her

chil-dren for admission, multivariate analysis shows that

a maternal age up to 24 years carries positive risk

coefficients. It may be assumed that the experience and maturity of the older mother significantly re-duce the risk of hospitalization since experience and maturity improve maternal capacity.

Studies on the immunization status of a cohort

sample and on the hospitalizations of older siblings,

as well as multifactorial analysis of second or

fur-ther hospital admissions did not yield significant data.

Using the risk coefficients of these significant single factors deduced by multivariate analysis, a numerical risk score of hospitalization was calcu-lated. The use of a risk coefficient of 0.20 and over

on the cohort predicted 43.3% of the total initial admissions offering 23.3% of the total cohort. De-spite the possible criticism that the studied cohort did not represent consecutive births, the study it-self was based only on groups within this unselect-ed cohort alone and would, therefore, appear to be reliable.

These risk coefficients predicting the

hospitaliza-tion of Haifa children may be applicable to other

communities. The wider applicability of the method

is being investigated within a different cohort of consecutive newborns in Jerusalem.

The scoring method ranked 23.3% of the Haifa cohort as “high risk of hospitalization,” yielding 43.3% of the initial admissions. The value of such

scoring and subsequent allocation of health services can only be proven by a prospective “therapeutic

trial” within the community. A group of “at risk”

infants could be defined at birth on the basis of

“risk coefficients.” One half of the families in the

“at risk” group could receive additional health guidance by a simple routine, such as extra home

visits by public health nurses. A follow-up period

would be able to show whether the “at risk” group

is indeed admitted to hospital more than the control group, and whether selective care allocation leads to a reduction in hospitalization. This might be provided by central medical record linkage.

REFERENCES

1. Winter, S. T. : The Hospitalization of Young Haifa

Children, (U.S.A., H.E.W., Isr/CB/19 Report), Haifa, M.D. thesis. University of Leeds, 1971. 2. Feldstein, M. S., and Butler, N. R. : Analysis of factors

affecting perinatal mortality: A multivariate

stalls-tical approach. Brit. J. Soc. Prey. Med., 19:128, 1965.

3. Feldstein, M. S.: A method of evaluating perinatal

mortality risk. Brit. J. Soc. Prey. Med., 19:135, 1965.

4. Douglas, J. W. B.: An Account of Hospital Admissions

in the Pre-School Period. London: Joint

Commit-tee of Institute of Child Health of University of London, Society of Medical Officers of Health and Population Investigation Committee, 1955. 5. Spence, J., Walton, W. S., Miller, F. J. W., and Court,

S. D. M. : A Thousand Families in

Newcastle-upon-Tyne, Oxford. London: Oxford University

Press, 1954.

6. Drillien, C. M. : The Growth and Development of the

Prematurely Born Infant. Edinburgh: Livingstone,

1964.

7. Rantasalo, V., and Valpola, H. : On social factors as a

cause of children’s hospital treatment. Ann. Paediat. Fenn., 1 :315, 1955.

8. Christensen, V. : Housing conditions and child

morbid-ity: Relation of different housing factors to hos-pitalization rate in children. Acta Paediat., 46:90,

1957.

9. Vaananen, I. : Social factors and hospital admission rate of children. Ann. Hyg. Med. Soc. Fenn., 2:225,

1963.

10. Straus, P., Coiffard, N., Marzo-Weyl, S., and Lenoir, M. : L’Hospitalisation des Enfants. Monographie de L’Institut d’Hygiene, No. 23, Paris, 1961.

11. Hottinger, A., and Berger, H. (eds. ): Seminar on hospitalization of children, Paris, 1963. Mod. Prob. Pediat., 9:1965.

12. Acheson, E. D.: Hospital morbidity in early life in re-lation to certain maternal and foetal characteristics and events at delivery. Brit. J. Soc. Prey. Med., 19:164, 1965.

13. Field, C. M. B., and Millar, S.: Admission of children to hospital. Ulster Med. J., 38:172, 1969. 14. Winter, S. T., and Mainzer, W. : Factors in the

hos-pitalization of Haifa children. Israel Med. J., 20:

143, 1961.

15. Winter, S. T., and Mainzer, W. : Premature birth and subsequent admission to hospital. Brit. J. Soc.

Prey. Med., 14:80, 1960.

16. Winter, S. T. : The male disadvantage in disease acquired in childhood. Develop. Med. Child Neurol., 14: 517, 1972.

17. Shuval, J. T. : Social Functions of Medical Practice. San Francisco : Jossey-Bass, 1970.

ACKNOWLEDGMENT

Supported by grant Isr/CB/19 from the Children’s Bu-reau of the U.S. Dept. of Health, Education and Welfare.

This study was possible only through the generous

co-operation, help and advice of many physicians, nurses,

officials and others. We wish especially to thank Prof. A.

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1974;53;716

Pediatrics

S. T. Winter and Pearl Lilos

Prediction of Hospitalization During Infancy: Scoring the Risk of Admission

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Pediatrics

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Prediction of Hospitalization During Infancy: Scoring the Risk of Admission

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