AGE STANDARDS FOR PERFORMANCE ON THE TEST OF INFANT MOTOR PERFORMANCE. Suzann K. Campbell* Physical Therapy, University of Illinois at Chicago, Chicago, IL PURPOSE: The goal of this study was establishment of age standards for performance on the Test of Infant Motor Performance (TIMP) to facilitate its use as a tool to diagnose delayed motor development. BACKGROUNDS/SIGNIFICANCE: The TIMP is a test of functional motor performance in infants from 34 weeks postconceptional age (PCA) through 4 months post term. Test items reflect demands for movement placed on infants by their caregivers during dressing, bathing, and play. Total scores on the TIMP range from 0-142. Validity for predicting 12-month and 5-year motor outcome has been documented, and children with cerebral palsy show delayed performance as early as 7 days post- term. The test has been demonstrated to have sensitivity to the effects of physical therapy provided in the special care nursery or as a home program carried out by parents in controlled clinical trials. Performance norms are available for infants from the Chicago metropolitan area but were needed for infants of all races/ethnicities from across the U.S. Availability of age standards from a U.S. normative sample will allow the TIMP to be used for diagnosing developmental delay in infants at risk for impaired motor outcome. SUBJECTS: Subjects were 990 infants recruited in 12 medical centers across the U.S. in proportions intended to reflect the distribution of race/ethnicity in low birthweight infants (1996 National Center for Health Statistics data). In each 2-week age group (34-35 wks PCA through 16-17 wks post-term), approximately one-third of infants recruited were high, medium and low risk, respectively, for impaired motor outcome based on medical complications in the perinatal period. METHODS AND MATERIALS: Each infant was tested once with the TIMP during the 2-wk age range for which s/he was recruited (age adjusted for premature birth when necessary) by a reliable rater masked to infant age and risk. ANALYSES: Raw score totals for all infants in each age group were averaged to form age expectations for each 2-wk time period from 34-35 wks PCA through 16- 17 wks post-term. Multiple regression analysis was used to explore the effect on TIMP total raw scores of sex, risk for impaired motor outcome, and race/ethnicity while controlling for age at testing. RESULTS: The total number of subjects enrolled in each 2-wk age group ranged from 67 to 97. Males made up 52% of the subjects. Fifty-eight percent of the sample was white, 25% black, and the remainder distributed among Latino, Asian, and Native American infants. Mean scores ranged from 49 (SD=15) for infants 34-35 wks PCA through 120 (SD=16) for infants 16 through 17 wks post-term. Thus there was no floor or ceiling effect. Group means were similar to previously published age standards for Chicago area infants except for the 34-35 wk group whose average score increased by 5 points. High risk infants scored significantly less well than medium and low risk infants (Beta=-.133, p<,0001), and Latino infants scored less well than infants of all other ethnicities (Beta=-.052, p<,006). Performance on the test did not differ significantly by sex. CONCLUSIONS: These U.S. age standards for performance on the TIMP can be used to identify infants with delayed functional motor performance. The TIMP is the only test designed for use with infants born prematurely or others at risk for poor motor outcome that can be used both in special care nurseries and in early intervention settings to diagnose delayed motor development, plan intervention programs, and measure outcomes. FUNDING SOURCE: National Institutes of Health R01 HD 38867. Statement of interests: The author is the managing partner of Infant Motor Performance Scales, LLC, the distributor of the TIMP. KEYWORDS: premature infants, motor development, norms, diagnosis, early intervention Age Standards for TIMP Performance Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.