Stability of the Motor Optimality Score Revised (MOS-R) in medically complex infants

Background: The Motor Optimality Score-Revised (MOS-R) is a clinical test of infant spontaneous movement at 3–5 months of age and has been associated with neurodevelopmental outcomes in infants with medical complexity. However the stability of the MOS-R tested at different developmental ages is not yet known. Aim: To determine if the repeated scoring of the MOS-R remained consistent when tested at two developmental ages in young infants. Study design: In this prospective cohort study, infants were tested twice with the MOS-R between 12 and 13 weeks corrected age (CA) and 14–16 weeks CA. Bland Altman Plots were used to calculate agreement between the scores. Infants were grouped as having higher or lower medical complexity. MOS-R threshold scores were analyzed to assess changes over time within each group using Fisher's exact test. Subjects: 85 infants with history of hospitalization in a neonatal intensive care unit (NICU). Results: The MOS-R scores had a high agreement with negligible bias (0.058) between timepoints (95 % CI -1.10, 1.22). Using a MOS-R cut point of 19, infants with higher medical complexity were more likely to change groups between timepoints than infants with lower medical complexity (p = 0.008), but this was not significantly different using cut points of 20 or 21. Conclusion: The MOS-R scores were stable when measured repeatedly in infants who were hospitalized in a NICU. Infants with high medical complexity had less stable MOS-R scores using certain cut points than infants with lower medical complexity.