Adherence and drop-out in randomized controlled trials of exercise interventions in people with multiple sclerosis: A systematic review and meta-analyses.

Background: The short-term benefits of exercise in people with multiple sclerosis (MS) are well established. To sustain benefits exercise needs to continue long-term. Despite important clinical implications, no systematic reviews have synthesized evidence on adherence and drop-out in MS exercise interventions.

Objectives: 1) To summarize reported adherence and drop-out data from randomized controlled trials (RCTs) of exercise interventions, and 2) identify moderators related to adherence and drop-out.

Methods: Nine databases were electronically searched in October 2018. Included studies were RCTs of exercise interventions in adults with MS published from January 1993 to October 2018. Abstracts and full texts were independently screened and selected for inclusion by two reviewers. Methodological quality was assessed using the TESTEX rating scale.

Results: Ninety three articles reporting 81 studies were included. Forty one studies (51%) reported both adherence and drop-out data during the intervention period with three (4%) also reporting follow-up data. Of the 41 studies, < 25% pre-defined adherence or described how adherence was measured. Meta-analyses of 59 interventions (41 studies) showed a pooled adherence estimate of 0.87 (95% CI 0.83 to 0.90) and 0.73 (CI 0.68-0.78) when including drop-outs. Mean age, proportion of females and intervention duration were inversely associated with adherence.

Conclusion: Little consensus existed on definition of adherence or determination of drop-out in MS exercise studies, with reporting generally of poor quality, if done at all. Hence it is largely unknown what can moderate adherence and whether exercise continued following an exercise intervention. Researchers should ensure clear transparent measurement and reporting of adherence and drop-out data in future trials.