Background and purpose: The purpose of this study was to assess the construct validity of the Test of Infant Motor Performance (TIMP), specifically the test's sensitivity for assessing age-related changes in motor skill and correlation with risk for developmental abnormality.
Subjects: Subjects were 137 term and preterm infants stratified by postconceptional age, medical complications score on the Problem-Oriented Perinatal Risk Assessment System, and ethnicity and race (non-Latino Caucasian, African-American, and Latino).
Methods: Subjects were tested on the TIMP at ages ranging from 32 weeks postconceptional age to 3.5 months past term-equivalent age. Scores (Rasch logit ability measures) were correlated with postconceptional age. A multiple regression analysis was used to assess the contributions of age, risk, and ethnicity to the variance in TIMP scores.
Results: The correlation between postconceptional age and TIMP performance measures was .83. Risk and age together explained 72% of the variance in TIMP performance (R = .85, P < .00001). No differences related to ethnicity were found.
Conclusion and discussion: The TIMP has validity for assessing age-related development of functional motor skills in young infants and is sensitive to risk for poor developmental outcome.