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Measuring Function in Young Children with Impairments

Tucker, Carole A. PhD, PT, PCS; Watson, Kyle E. DPT, PT

Pediatric Physical Therapy: April 2010 - Volume 22 - Issue 1 - p 51
doi: 10.1097/PEP.0b013e3181ce1685
Clinical Bottom Line

Physical Therapy Department, Shriners Hospital for Children, Philadelphia, Pennsylvania (Tucker)

College of Health Professions and Social Work, Temple University, Philadelphia, Pennsylvania (Watson)

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“How should I apply this information?”

The WeeFIM 0-3 instrument described in this report measures “early function” as represented by a set of motor and cognitive skills thought to be precursors to later basic daily living functions and behavioral perceptions of caregivers. The 2 existing functional independence measures for adults (FIM) and older children (WeeFIM) focus on functional independence, and the addition of the WeeFIM 0-3 instrument completes a set of functional measures across the lifespan. If one's practice would benefit from the measure of prefunctional skills, rather than developmental skills, in combination with caregiver perceptions of care, the WeeFIM 0-3 may be an appropriate measure to adopt, particularly within pediatric rehabilitation settings or by practices that rely on the use of the WeeFIM in older children.

The psychometrics, or measurement properties, of the instrument are determined using “modern measurement” approaches. These statistical approaches include factor and item response theory analyses, and provide a more comprehensive understanding of the instrument measurement properties than other more traditional, and perhaps familiar, approaches. Such analyses are becoming more commonplace in the pediatric physical therapy literature and also are reported in a second manuscript in this issue.1 Therapists should welcome such analyses because they provide an interval scaling of the item's difficulty and provide a better sense of the items interrelationships. The Wright maps for the WeeFIM 0-3 (Fig. 1) provide a great visual of how the items compare with one another and to the people who were assessed. Floor, ceiling, and gaps in item content can be easily visualized, and what skills may be “next” in terms of difficulty.

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“What should I be mindful about in applying this information?”

In applying this information, one should consider several factors as one does for any report on outcome measurements. First, is the underlying concept, in this case the existence of prefunctional skills, something of value in one's practice? To determine this, review both the author's description of the conceptual framework and the individual items. Although there does seem to be some overlap with existing developmental instruments in the motor and cognitive domains, the third domain, behavioral perceptions, is intended to capture the difficulties or tensions between caregiver and child—not child-specific behaviors. This concept is not always reflected in developmental measures and may provide insights for the clinician.

The authors clearly state this measure is intended to be used to measure the effect of interventions, primarily within pediatric rehabilitation settings. In children 0 to 3 years of age, measures that can identify developmental delay to determine whether a child qualifies for intervention services are used in practice, and this measure may not fill that need or be as useful in other practice settings. In addition, future work assessing the predictive validity and responsiveness of this measure with longitudinal design, and clinical validation in other setting would be beneficial before the measures use in such different applications.

In many recent reports of outcome measures, the use of factor and item response theory analyses have emerged and are incredibly informative in the characterization and development of outcome measurement development. Factor analyses as performed in this study provide information concerning how well the item set fits together and is consistent with the underlying framework of 3 domains. Item response theory analyses provide important information concerning the measurement characteristics and behavior of individual items and relationships between items are better quantified. Measures developed using item response theory analyses may be less population dependent but require large number of subjects with skills across the range of the tested concepts (motor, cognitive, and behavioral perceptions). The reported analyses focused only on children with disability and relied on data from a relatively small number of subjects. This means the results may have limited application in measurement of higher functioning children, and the item levels may not be as sensitive to change if data were collected on a larger number of subjects. One must consider, however, that even with the use of these newer and more informative procedures, it is still important to consider the reliability of the instrument, which in this case is not reported in this article.

The WeeFIM 0-3 in this study was administered as a questionnaire sent home to the parents rather than clinician interview. This slight difference from the existing FIM measures, however, may lessen administration burden in the clinic setting.

Based on this report, the WeeFIM 0-3 has good measurement properties and could be used to measure early function as proposed within the pediatric rehabilitation setting. Additional work defining the responsiveness over time would be of benefit.

Carole A. Tucker, PhD, PT, PCS

Physical Therapy Department, Shriners Hospital for Children, Philadelphia, Pennsylvania

Kyle E. Watson, DPT, PT

College of Health Professions and Social Work, Temple University, Philadelphia, Pennsylvania

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1.Haley SM, Coster WJ, Kao Y-C. Lessons from use of the Pediatric Evaluation of Disability Inventory: where do we go from here? Pediatr Phys Ther. 2010;22:69–75.
© 2010 Lippincott Williams & Wilkins, Inc.