Concurrent and predictive validity of the Alberta Infant Motor Scale and the Peabody Developmental Motor Scales-2 administered to infants born preterm in Norway.

Background: The correlation between the Alberta Infant Motor Scale (AIMS) and the Peabody Developmental Motor Scales-2 (PDMS-2) has not previously been assessed in Norwegian infants. Our purpose was to investigate the concurrent validity of the AIMS and the PDMS-2 in a group of high-risk infants, and to investigate the predictive validity of the two tests for atypical motor function at 24 months post term age (PTA).

Methods: This is a retrospective study of the AIMS and the PDMS-2 administered to infants born preterm with gestational age ≤ 32 weeks (n = 139) who had participated in a randomized controlled trial of early parent-administered physiotherapy. The infants' motor development had been assessed using the AIMS and the PDMS-2 at 6- and 12-months. The primary outcome was PDMS-2 at 24-months PTA. To explore the correlation between the two tests we used Spearman's rho. Bland Altman plots were used to detect if there were systematic differences between the measurements. Receiver-operating characteristics curves were used to calculate area under the curve as an estimate of diagnostic accuracy of the AIMS and the PDMS- with respect to motor outcome at 24 months.

Results: The correlation between the AIMS and the PDMS-2 (total motor and locomotion subscale), at 6 months, was r = 0.44 and r = 0.76, and at 12 months r = 0.56 and r = 0.80 respectively. The predictive validity for atypical motor function at 24 months, assessed using the area under the curve at 6- and at 12- months, was for the AIMS 0.87 and 0.86, respectively, and for the PDMS-2 locomotion subscale 0.82 and 0.76 respectively.

Conclusion: The correlation between the AIMS and the PDMS-2 locomotion subscale, at 6- and 12- months PTA, was good to excellent in a group of infants born preterm in Norway. And the AIMS and the locomotion subscale of the PDMS-2 were equally good predictors for atypical motor outcomes at 24 months PTA. These findings indicate that the AIMS and the locomotion subscale of the PDM-2, could be used interchangeable when assessing motor development in infants at 6- or 12 months of age.

Trial Registration: ClinicalTrials.gov NCT01089296.