INFLUENCE OF MEDICAL HISTORY ON ASSESSMENT OF AT-RISK INFANTS

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Barbara Ashton Martha C. Piper Sharon Warren Leonard Stewin Paul Bvrne

The continuing expansion and increasing sophistication of neonatal intensive-care facilities have accelerated interest in screening survivors of these units for developmental problems. Accurate, early identification of infants exhibiting developmental delay and of those at risk for developmental problems is a challenge for professionals who perform screening assessments. Since high false positive and false negative rates continue to be reported, the investigation of factors that could lead to screening inaccuracies is important (Harris 1987, Aylward et al. 1988, Piper et al. 1989). False positive results of infant screening may be of more consequence than has generally been assumed, since a number of investigations have reported the negative effects of informing parents of false positive test results (Bergman and Stamm 1967; Kearsley 1979; Bodegard et al. 1983; Sorenson et al. 1984; Tymstra 1986; Fyro and Bodegard 1987, 1988; Heyerdahl 1988). These studies describe increased parental anxiety and disturbed child behaviour long after false positive tests have been corrected.

The possible influence of knowing the medical history on the assessments of at- risk infants has not been investigated previously. We considered that such knowledge would affect clinicians' assess- ments of at-risk infants, since traditionally

a strong association has been assumed between perinatal events and the occurrence of neuromotor problems. More recently, however, a number of investigations have cast doubt on the power of perinatal events to predict cerebral palsy and other developmental problems (Paneth and Stark 1983; Nelson and Ellenberg 1986, 1987; Paneth 1986; Kitchen et al. 1987; Pharoah et al. 1987; Stanley 1987; Nelson 1988; Largo et al. 1989). The specific aim of this investi- gation was to examine the influence of physical therapists' previous knowledge of the medical history on assessments of at-risk infants.

Method Two at-risk infants, one with a low-risk and one with a high-risk medical history, were identified for assessment (Table I). The low-risk infant was a preterm infant of 32 weeks gestation; the high-risk infant was a fullterm, asphyxiated infant. Both were assessed by an experienced physical therapist at four months adjusted age, using the Movement Assessment of Infants (MAI) examination, and the assessments were videotaped.

The MAI is commonly used by physical therapists to assess the neuromotor status of at-risk infants during the first year of life (Chandler et al. 1980). It comprises 65 items, divided into four sections-muscle

tone, primitive reflexes, automatic re- actions and volitional movement. Scores for 47 of the 65 items are designated as either normal or questionable for an infant of four months of age. Risk points for all four sections are summed to obtain a total risk score; an increased risk score signifies heightened risk for delay in motor development.

Inter- and intra-observer reliabilities have been reported as varying from poor to excellent, with the majority of items demonstrating fair to good reliability (Harris et al. 1984a, Haley et al. 1986). Good predictive validity for this test for one- and two-year developmental out- comes has also been reported (Harris et al. 1984b).

Forty-one paediatric physical therapists, blind to the research hypothesis, partici- pated in the study. Paediatric physical therapists were defined as those currently working in paediatrics. Their mean paediatric work experience was 7 - 5 years.

The therapists were trained in the use of the MAI. Following training, the level of inter-rater reliability, measured by the coefficient of variability, was <0*20 for total risk scores.

Therapists were randomly assigned to one of four groups. Each group viewed a videotaped infant examination under one of four different knowledge conditions: (A) high-risk infant, knowlege of an accurate high-risk history (N = 10); (B) high-risk infant, knowledge of the history of the low-risk infant ( N = 10); (C) low- risk infant, knowledge of an accurate low- risk history ( N = 11); and (D) low-risk infant, knowledge of the history of the high-risk infant (N = 10).

Before the beginning of data collection, the therapists were asked not to discuss any aspect of the study during its course. The therapists in each knowledge group viewed the videotape simultaneously, each group in a separate room. A copy of the infant’s medical history was given to each therapist before the viewing. They viewed the videotaped examination once before scoring the MAI, after which they completed a questionnaire regarding the neuromotor prognosis of the infant, the need for further evaluation and the need for physical therapy.

TABLE 1 Medical histories

Low-risk infant 32 weeks gestation Apgar scores 3 at one minute; 8 at five minutes Birthweight 1140g Mild respiratory distress syndrome Normal discharge neurological examination

High-risk infant Asphyxiated fullterm infant Apgar scores 1 at one minute; 1 at five minutes; 2 at

10 minutes Birthweight 37808 Severe hypoxic-ischaemic encephalopathy Markedly abnormal EEG and cranial CT Abnormal discharge neurological examination

Results The mean MA1 total risk scores were calculated and are listed according to risk status and medical history in Table 11. Two-way factorial analyses of variance were performed on total risk scores and section risk scores with the following two factors: physical therapist’s knowledge of medical history and actual medical history. The responses to the question- naire were examined using x 2 analyses, with an alpha level of 0.05 determining statistical significance.

Statistical analyses revealed a signifi- cant effect of physical therapists’ knowledge of history on total risk scores, and on section risk scores for muscle tone and primitive reflexes, but not for auto- matic reactions and volitional movement. A significant effect of actual medical history was found for total risk scores, and for section risk scores for muscle tone, primitive reflexes and automatic reactions, but not for volitional move- ment. There was no significant interaction effects for any of the analyses of variance, indicating that the effect of knowledge of medical history on MA1 scores was the same for both infants (Table 111).

Analysis of question 1, ‘How would you rate this infant’s neuromotor status? (normal, suspicious, or abnormal)’, revealed a significant effect of knowledge of medical history for the low-risk infant. With knowledge of a high-risk history, eight of the 10 therapists rated the low-risk infant as suspicious, one as abnormal and one as normal. With knowlege of a low-

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TABLE I1 Mean risk scores according to risk status and medical history

Factors Total risk Muscle tone Primitive Automatic Volitional score reflexes reactions movement

Mean (SO) Mean (SO) Mean (SO) Mean (SO) Mean (SO) Range

High-risk infant with 17.30 (3.59) 4-80 (1.81) 5 .70 (1.34) 3.20 (1-48) 3.60 (0.70)

High-risk infant with 15.10 (4.65) 3 .90 (2.13) 5 .20 (1.32) 2.80 (1-03) 3.20 (1.81)

Low-risk infant with 10.70 (6.45) 2 .00 (1.33) 4 .90 (2.47) 0 .60 (1.27) 3.20 (1.99)

Low-risk infant with 6 .00 (4.36) 0.55 (1.04) 3.00 (1.84) 0.18 (0.60) 2.27 (1.90)

high-risk history 9-2 1

low-risk history 7-2 1

high-risk history 1-16

low-risk history 4-26

TABLE I11 Analyses of variance: Movement Assessment of Infant’s risk scores

Factors Total risk Muscle tone Primitive Automatic Volitional score reflexes reactions movement

Mean p Mean p Mean p Mean p Mean p

Actual medical history High-risk 16-20 O.OOO1 4.35 O*OOOl 5.45 0.01 3.00 O*OOO1 3.40 NS Low-risk 8.24 1.24 3.91 0.38 2.71

historv Knowledge of medical

High-ksk 14.00 0.03 3.40 0.03 5.30 0.04 1.90 NS 3.40 NS Low-risk 10.33 2 .14 4.05 1 a43 2.71

risk medical history, two of 11 rated the same infant as suspicious, one as abnor- mal and eight as normal. For the high-risk infant, no statistically significant difference was found in the therapists’ impression of neuromotor status between histories.

Analysis of question 2, ‘Do you feel it is warranted to review this infant’s status at a future date? (yes, no)’, revealed a statistically significant difference in responses for the low-risk infant. When assessed with knowledge of a high-risk history, nine of the 10 therapists recom- mended review of this child; when assessed with a low-risk history, four of 11 recommended review. For the high-rjsk infant, there was no significant difference in the responses of the two groups.

Analysis of question 3, ‘Do you feel that this child requires intervention by a physical therapist at this time? (yes, no)’ 414

revealed no statistically significant effect of knowledge of the medical history for either infant (Table IV).

Discussion These results suggest that knowledge of an infant’s medical history influences the scoring of a neuromotor examination. Mean total risk scores and section risk scores for muscle tone and primitive reflexes were lower for the high-risk infant with a low-risk medical history than with a high-risk history. Similarly, mean total risk and section risk scores for muscle tone and primitive reflexes were higher for the low-risk infant with a high- risk history than with a low-risk history. This pattern of scoring is consistent with the expectancies that are believed to be associated with high- and low-risk medical histories.

There were no statistically significant

TABLE IV Questionnaire response

m N -r

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Question ~~

High-risk history Low-risk history XZ P

1. Impression of neuromotor status High-risk infant

Normal Suspicious Abnormal

Lo w-risk in fan I Normal Suspicious Abnormal

2. Need for review High-risk infant

Yes No

Yes No

Low-risk infant

3. Need for intervention High-risk infant

Yes No

Yes No

Low-risk infant

0 7 3

1 8 1

10 0

9 1

9 1

3 7

1 2.067 NS 8 1

8 9.017 0.01 2 1

10 0

NS

4 4.318* 0.04 7

5 2.143* NS 5

0 1.79* NS 11

*Calculated using continuity correction.

effects of previous knowledge for either the automatic reactions or volitional movement sections of the examination. Since different sections of this examin- ation measure different aspects of neuro- motor behaviour, it is possible that knowledge of medical history may bias the therapists’ perceptions of some aspects of motor behaviour more than others. They may believe that muscle tone and primitive reflexes are more important indicators of normal or abnormal neuro- motor status than automatic reactions and volitional movement (Drillien 1972, Capute 1979, Ellenberg and Nelson 1981, Touwen and Hadders-Algra 1983), and thus assume that the items that measure muscle tone and primitive reflexes are more likely to be affected by past medical events (Bobath 1971, Fiorentino 1973).

Another explanation might be that the muscle tone and primitive reflexes items are more open to interpretation and thus subject to greater bias than items included in the automatic reactions and volitional movement sections.

The infant with an actual high-risk medical history obtained higher total risk

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and section risk scores for muscle tone, primitive reflexes and automatic reactions than the infant with the actual low-risk medical history. This scoring pattern suggests that the MAI does discriminate low-risk from high-risk infants. While actual medical history did not have a statistically significant influence on the volitional movement scores, the mean differences were in the expected range. It may be that the volitional movement items only detect major deviations from normal, and that such major deviations were not observable in these infants.

While the interaction effects between knowledge of medical history and actual risk status were not statistically significant, the clinical significance of the findings varied according to the risk status of the infants. When interpreting the results of this examination, total risk scores of > 10 are commonly used to identify infants who are considered to be at high risk for neuromotor problems (Swanson et al. 1988). For our high-risk infant with an actual high-risk history, the mean total risk points were 17.3, compared with 15.1 for the same infant with a low-risk 415

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416

medical history. Both of these total risk scores indicate a very high-risk status for this infant in relation to usual classification criteria.

In the case of the low-risk infant with a low-risk history, the mean total risk points were 6.0, compared with 10.7 for the same infant with a high-risk history. These two scores would probably be interpreted quite differently clinically: the higher score would indicate that this infant was at risk for neuromotor prob- lems, while the lower score would be less likely to elicit concern. This discrepancy could lead to different clinical recom- mendations for further review or treat- ment of this infant.

It is of interest that examination of these two infants at 18 months by a paediatric neurologist, using the neuro- logical examination of the National Col- laborative Perinatal Project (Hardy et al. 1979), resulted in the low-risk infant being classified as normal and the high-risk infant as neurologically suspicious, al- though there was no significant disability.

The most important implications of this investigation relate to the assessment of the low-risk infant. When assessed with a high-risk medical history, this infant was rated in a range that would indicate con- cern; the questionnaire responses indicated that the majority of therapists perceived this infant’s neuromotor status to be suspicious and would recommend review. This suggests that special concern should be paid to the validity of assessments of infants whose neuromotor behaviour is within normal limits, but who are known to have a high-risk medical history. This could lead to a false positive result, which, if communicated to the parents, could cause them unnecessary worry and concern. Past investigations have indicated that false positive results may have a significant impact on parents’ perceptions and interactions with their child, in addition to the more obvious drawbacks associated with costly, unnecessary re- assessment or treatment (Green and Solnit 1964; Illingworth and Illingworth 1964; Bergman and Stamm 1967; Kearsley 1979; Levy 1980; Bodegard et al. 1983; Illing- worth and Illingworth 1984; Sorenson et al. 1984; Tymstra 1986; Fyro and Bodegard 1987, 1988; Heyerdahl 1988).

The assessments in this investigation were completed after viewing videotapes of infant motor activities, and were not typical assessments in which the physical therapist interacts directly with the infant. However, such direct interaction does raise the possibility of self-confirming behaviour on the part of the infant in response to the physical therapists’ inter- action (Field 1981).

The possibility that expectations related to knowledge of past medical history may influence other professionals involved in the assessment of at-risk infants also merits investigation. It is extremely un- likely that such expectations would influence only physical therapists.

These findings support the recom- mendation that assessments of at-risk infants be completed without knowledge of their medical history. These would result in more objective information on the actual neuromotor status of these infants. The disadvantages of assessment without knowledge of past medical events are minimal. However, it would be necessary to provide the examiner with knowledge of medical contra-indications which could limit or prohibit the use of some assessment procedures with specific infants. Increased attention to the edu- cational curriculum for physical therapy students and other health-care pro- fessionals as to the limitations in predicting neurodevelopmental outcome of infants is also recommended. Present evidence indicates that risk factors for abnormal developmental outcome are unknown in a substantial number of cases, and those associated with labour, delivery and the perinatal period have only slightly greater predictive power than do prenatal factors (Nelson and Ellenberg 1986, Stanley 1987). Further investigation of the influence of knowledge of medical history on the assessment of at-risk infants is required, particularly in situ- ations in which there is direct interaction between examiner and infant.

Accepted for publication 7th December 1990.

Acknowledgements This research was supported by National Health Research and Development Program, Health and Welfare Canada and Alberta Heritage Foundation for Medical Research, Government of Alberta, Canada. The Glenrose Rehabilitation Hospital and

the Alberta Children’s Hospital provided space and Sharon Warren, Ph.D., Associate Professor, equipment for data collection during this project. Faculty of Rehabilitation Medicine; The authors express their appreciation to the Leonard Stewin, Ph.D., Professor, Department of physical therapists and to the parents of the infants Educational Psychology, Faculty of Education; who participated in this project. They also thank Paul Byrne, M.B., Ch.B., F.R.C.P.(C), Assistant Annette Kujda for her assistance in the preparation Professor, Department of Pediatrics, Division of of the manuscript. Newborn Medicine;

University of Alberta, Edmonton, Alberta, Canada. Aufhors’ Appoin fments Barbara Ashton, hl.Sc., Clinical Supervisor, Physical Therapy Department, Glenrose Rehabili- *Correspondence to second aufhor at Faculty of tation Hospital; Rehabilitation Medicine, 3073 Nurses’ Residence, *Martha C. Piper, Ph.D., Professor, Dean, Faculty University of Alberta, Edmonton, Alberta T6G of Rehabilitation Medicine; 2G4, Canada.

SUMMARY The influence of knowledge of their medical history on the assessment of at-risk infants was examined. Two at-risk infants, one with a high-risk medical history and one with a low-risk history, were assessed and videotaped using the Movement Assessment of Infants. 41 physical therapists were randomly assigned to assess the videotaped examinations in four groups with different knowledge of the infants’ histories (high-risk infant with actual or low-risk history; low-risk infant with actual or high-risk history). The clinical significance of the difference in total risk scores between knowledge conditions of a high-risk history and a low-risk history was greater for the low-risk infant. The higher mean total risk score for the low-risk infant assessed with a high-risk history suggests that false positive results could occur which may alter parents’ perceptions and interactions with the infants and consequently influence their development.

Infruence de I’histoire medicale sur I’examen des nourrissons a risque L’influence de la connaissance de l’histoire medicale passee sur I’evaluation des nourrissons a risque a ete analysee. Deux nourrissons a risque, l’un avec une histoire a haut risque et l’autre avec une histoire medicale a bas rique, ont ete examines en particulier a I’aide de videos utilisant I’evaluation du mouvement du nourrisson. 41 kinesitherapeuthes ont ete choisis au hasard pour analyser les examens video en fonction de quatre conditions differentes de connaissance (nourrisson a aut risque avec haut reel ou histoire sans risque, nourrisson sans risque avec histoire sans risque reel ou histoire supposee a haut risque). La signification clinique de la difference sur les scores du risque total entre la condition de la connaissance d’une histoire a haut risque et I’histoire a bas risque a ete plus importante pour le nourrisson a bas risque. Le score de risque total moyen 1e plus eleve a kte obtenu pour les enfants a bas risque quand ils etaient &values avec une histoire a haut risque. Cela suggere que des resultats faussement positifs peuvent survenir dans cette situation qui, si elle est communiquee aux parents, peut alterer leur perception, leur interaction avec le nourrisson et influencer ultirieurement son developpement.

ZUSAMMENFASSUNG Beein flu& die Kenntnis der Anamnese die Beurteilung von Risikokindern Es wurde untersucht, ob die Kenntnis der Anamnese die Beurteilung von Risikokindern beeinflufit. Zwei Risikokinder, eins mit einem hochgradigen Risiko und eins mit einem geringen Risiko, wurden anhand der Movement Assessment of Infants beurteilt und auf Video aufgenommen. Unter vier unterschiedlichen Informationsbedingungen (high-risk Kind mit tatsachlicher oder mit low-risk Anamnese; und low-risk Kind mit tatsachlicher oder mit high-risk Anamnese) wurden 41 Physiotherapeuten gebeten, die Untersuchchungen auf dem Videofilm zu beurteilen. Die klinische Signifikanz der Unterschiede bei den Beurteilungen des Gesamtrisikos zwischen den Informationsbedingungen einer high-risk Anamnese und einer low-risk Anamnese war fur die low- risk Kinder grol3er. Der hohere durchschnittliche Risikoscore, der fur die low-risk Kinder ermittelt wurde, wenn sie unter der Vorgabe einer high-risk Anamnese beurteilt wurden, zeigt, dal3 falsch positive Ergebnisse in dieser Situation auftreten konnen. Werden diese den Eltern mitgeteilt, so konnen sie deren Beziehungen und Interaktionen mit den Kindern verandern und dadurch die Entwicklung der Kinder beeinflussen. RESUMEN Influencia del historial medico en la evaluacion de lactantes con riesgo Se examino la influencia del conocimiento de la historia medica anterior, en la evaluacion de lactantes con riesgo a1 ser examinados. Dos niaos con riesgo, uno con una historia de alto riesgo y otro con una historia de bajo riesgo fueron evaluados y gravados en video utilizando el Movimiento de Evaluacion de Lactantes. 41 fisioterapeutas fueron asignados a1 azar para evaluar las gravaciones de video, bajo cuatro formas diferentes de conocimiento (lactante con alto riesgo con historia o situacion de bajo riesgo; historia de bajo riesgo con historia o situacidn actual de alto riesgo). La significion clinica de la diferencia en el total de puntajes de riesgo entre las condiciones de conocimiento de una historia de alto riesgo y otra de bajo riesgo era mayor en el lactante de bajo riesgo. El promedio total del puntaje de riesgo obtenido en el lactante con bajo riesgo, a1 ser evaluado con una historia de alto riesgo, sugiere que pueden darse resultados falsamente positivos en esta situacion, lo que de ser comunicado a 10s padres puede alterar sus percepciones e interacciones con el nirlo y con ello influir en su desarollo.

RESUME

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153-180.

81-86.

183-187.

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