Attrition, adherence, and compliance to exercise training interventions in persons with traumatic brain injury: a systematic review of training studies

Background: Exercise training (ET) is a promising rehabilitation approach for long-term negative consequences of traumatic brain injury (TBI). However, little is known regarding overall rates of attrition, adherence, and compliance to ET in TBI. Objective: The purpose of this systematic review was to estimate average attrition, adherence, and compliance rates in ET studies in persons with TBI. MethodsDatabases were searched from inception to April 15, 2024. Two authors independently extracted data related to attrition, adherence, compliance, and possible moderators identified a priori. Results: The average rate of attrition from 45 studies was 14.4%, although the majority of studies had small sample sizes (i.e. n < 42). Based on hierarchical linear regression, the most influential predictors of attrition were sample size and study design. A minority of studies reported adherence (44.4%) or compliance (22.2%) but those that did reported good average adherence (85.1%) and compliance (77.7%). These studies support the ability of persons with TBI to complete an ET intervention as prescribed. Conclusions: Researchers can use this information to ensure adequate power to detect a true effect of ET in persons with TBI. Researchers conducting ET studies in persons with TBI should clearly and thoroughly report data on attrition, adherence, and compliance.