A population-based study to determine the performance of the Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale to predict the Mental Developmental Index at 18 months on the Bayley Scales of Infant Development-II in very preterm infants

Objectives. To determine optimal ages to perform the Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS) and optimal "cutoff" score of the CAT/CLAMS to screen very preterm infants (<31 weeks) for severe cognitive-adaptive delay and to ascertain the sensitivity, specificity and likelihood ratios using optimal cutoff scores compared with the Mental Developmental Index (MDI) of the Bayley Scales of Infant Development II. Methods. A population-based cohort of very preterm infants who were born to mothers who resided in Nova Scotia or Prince Edward Island were evaluated at 4, 8, 12, and 18 months' corrected gestational age, which included a CAT/CLAMS by a physician. At 18 months' corrected gestational age, each child was assessed using the Bayley Scales of Infant Development II, the "gold standard" for developmental delay in young infants. The results of each CAT/CLAMS was compared with the 18-month MDI to identify significant developmental delay (MDI <70). Results. Optimal scores on the CAT/CLAMS to identify correctly MDI <70 were determined by using the κ statistic for chance independent agreement. Sensitivities and specificities for optimal cutoff scores were as follows: 4-month score <109 (88% and 37%), 8-month score <98 (75% and 82%), 12-month score <81 (63% and 99%), and 18-month score <83 (88% and 98%). Conclusion. Sensitivity and specificity of the CAT/CLAMS are high in very preterm infants at identifying major developmental delay at 12 and 18 months. For follow-up programs without psychology services, the CAT/CLAMS at 12 and 18 months is a reasonable screening tool to determine which children need expedited psychology referral for cognitive delay.