Aim: To explore intra-rater and inter-rater reliability of the Infant Motor Profile (IMP). The IMP is a video-based method assessing movement quality (movement variation, adaptability, symmetry and fluency) and motor skills in infants aged 3 to 18 months.
Method: The IMP assessment was performed on 50 infants aged 3 to 12 months recruited in connection with health control in primary health care, mean gestational age at birth 39.4 weeks, mean birthweight 3462 g. Seven infants had a moderately increased risk of developmental disorders. Three pediatric physiotherapists performed independent rating of the video recordings. One rater assessed the video recordings twice with a four-week interval.
Results: Intraclass correlation coefficient (ICC) for intra-rater reliability was found satisfactory for the total IMP score (ICC = 0.95), and the domains: performance (ICC = 0.98), variation (ICC = 0.74), adaptability (ICC = 0.93) and fluency (ICC = 0.86). The ICC value for symmetry was 0.65. For inter-rater reliability, ICC values were satisfactory for the total IMP score (ICC = 0.86-0.91), and the domains: performance (ICC = 0.98), variation (ICC = 0.71-0.82), adaptability (ICC = 0.99) and fluency (ICC = 0.82-0.81). The ICC values for symmetry varied between 0.13-0.35.
Conclusion: In this sample, including mostly low-risk infants, satisfactory intra- and inter-rater reliability for all domains were demonstrated, except for symmetry.
Keywords: Infant Motor Profile; Infant motor development; motor assessment; primary health care; reliability.