Table 2.

Terms and Definitions

Term	Definition
Study Enrollment Rate	Total number of infants whose parent consented to the infant’s participation in the study period divided by number of eligible infants in a time period
Cumulative Enrollment	Total enrollment during the specific period. (Usual care/SPEEDI- Early/SPEEDI-Late)
Withdrawal	Parent directly stating they no longer wanted the infant to participate in the study
Lost to Follow-up	Parent disengaged from the study despite multiple communication attempts with parent resulting in 2 consecutive missed assessment or intervention visits
Study Retention Rate	Total number of infants who had not withdrawn from the study or been lost to follow-up divided by number of infants enrolled. This could be calculated for the study as a whole or for each period by subtracting the number of infants lost to follow up or withdrew from previous time period from the denominator.
Missed Visit	Any visit described in the study protocol that was not completed. The reason for a missed visit was documented by study personnel if known. However, the rational was often multi-factorial during the pandemic periods.
Outcome Measure	This term is used to represent any individual tool used to determine if there was a change in the participants ability on that same tool over time, e.g., Test of Infant Motor Performance (TIMP) is an outcome measure.
Assessment Visit	This term is used to represent the visits with the participants in which multiple outcome measures are completed to evaluate change over time.
Assessment Visit Completion Rate	Total number of assessment visits completed during the study period divided by number of assessment visits scheduled based on the planned 5 visits per infant (baseline, visit 2, 3, 4, 5). Missed visits because of withdrawal or being temporarily lost to follow-up both result in reduced assessment completion rates.
Outcome Measure Completion Rate	This is the same as assessment visit completion rate, but applied at the level of the individual outcome measure. Since not all outcome measures could be completed at all planned visits, the denominator varied between outcome measures to reflect a lower denominator if the outcome measure could not be completed. Therefore, Outcome Measure Completion Rate was the total number of times a specific outcome measure was completed divided by the number of visits in which that measure was planned in the protocol.
Mode of Delivery	In-person, Telehealth, Hybrid
Missed Outcome Measure Rate	Total missed assessment measures divided by expected number of assessment measures.
Intervention Completion Rate	Total number of intervention visits completed during the study period divided by number of intervention visits scheduled.
Missed Intervention Visits Rate	Number of infants who missed one or more visits out of the visits scheduled in that time period.
Intervention Retention	Number of infants who did not drop out of the intervention either due to voluntary withdrawal or loss to follow-up.