Concurrent validity of the TIMP and the Bayley III scales at 6 weeks corrected age

Purpose: Examine agreement between the Test of Infant Motor Performance (TIMP) and the Bayley III. Methods: 145 infants born at 29-34 weeks gestation with socioenvironmental risk factors were tested on the TIMP and Bayley III at 6 weeks corrected age (CA). Scores were correlated to assess convergence/divergence of content. Decision analysis using a cutoff of the mean on the Bayley Motor Composite and -.5 and -1 SD from the mean on the TIMP assessed agreement on delay/non-delay. Results: The TIMP-Bayley Motor Composite correlation was .546, with Cognitive was .310, and with Language was .281. Nine percent of infants scored below -1.0 SD on the TIMP while no child performed below -1 SD on the Bayley Motor scale (sensitivity 31%). Conclusions: Convergent validity between the TIMP and the Bayley Motor scale was demonstrated, but no infant showed delay on any Bayley scale. The TIMP is preferred for early assessment of infants.