The reliability and predictive ability of the Test of Infant Motor Performance (TIMP) in a community-based study in Bhaktapur, Nepal

Aim: In a Nepalese setting, to measure the reliability of the Test of Infant Motor Performance (TIMP) and its ability to predict development scores at 6 months. Methods: Nepalese infants (n = 705) were assessed by the TIMP when they were 8-12 weeks old and the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-III) at 6 months. Inter-rater agreement was expressed by intraclass correlation coefficients (ICCs), the internal consistency by Cronbach's alphas and Pearson correlation coefficients. Predictive ability was estimated in linear regression models. Results: Inter-rater agreement was excellent (ICCs > 0.93). Alphas for the TIMP total scores were 0.76 for infants born to term and 0.72 in those born preterm. Correlation coefficients between TIMP total and Bayley-III subscale-scores ranged from 0.05 to 0.28 for term infants and from 0.15 to 0.43 for preterm infants. Using American norms, 56.3 % had TIMP scores within average and 43.7 % below average range. Bayley-III subscale scores were lower in children with TIMP scores below the average range, with the strongest estimates for Gross motor and Socio-emotional development. Interpretation: The reliability of the TIMP was acceptable, and the TIMP could be a feasible tool to monitor infant motor development in low-resource settings. Properties of the TIMP differed according to gestational age. Keywords: Infant motor development; Low-resource setting; Nepal; Psychometric properties; TIMP.