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.