Reliability and validity of the TIMPSI for infants with spinal muscular atrophy type I.

PURPOSE: This study examined the reliability and validity of the Test of Infant Motor Performance Screening Items (TIMPSI) in infants with type I spinal muscular atrophy (SMA). METHODS: After training, 12 evaluators scored 4 videos of infants with type I SMA to assess interrater reliability. Intrarater and test-retest reliability was further assessed for 9 evaluators during a SMA type I clinical trial, with 9 evaluators testing a total of 38 infants twice. Relatedness of the TIMPSI score to ability to reach and ventilatory support was also examined. RESULTS: Excellent interrater video score reliability was noted (intraclass correlation coefficient, 0.97-0.98). Intrarater reliability was excellent (intraclass correlation coefficient, 0.91-0.98) and test-retest reliability ranged from r = 0.82 to r = 0.95. The TIMPSI score was related to the ability to reach (P ≤ .05). CONCLUSION: The TIMPSI can reliably be used to assess motor function in infants with type I SMA. In addition, the TIMPSI scores are related to the ability to reach, an important functional skill in children with type I SMA.