Determining the optimal volume of reactive balance training after stroke: a pilot randomized controlled trial

Background: Our long-term goal is to determine the optimal volume of reactive balance training (RBT) in people with sub-acute stroke. This study aims to inform the design of a larger trial to address this long-term goal. Trial design: Assessor-blinded three-arm pilot randomized controlled trial. Methods: Participants (n=36) with sub-acute stroke were randomly allocated to one of three groups: 1, 3, or 6 RBT sessions. All sessions were delivered over 2-3 weeks. Feasibility outcomes included recruitment and retention rates, intervention fidelity and adherence, and completeness of outcome assessments. Participants reported falls and physical activity for 6 months post-training; falls data were used to estimate sample size for a future trial. Functional balance, balance confidence, and balance reactions were assessed at: 1) study enrolment; 2) post-training; and 3) 6 months post-training to estimate effect sizes for a future trial. Results: Thirty-five participants initiated training and 34 contributed post-training assessment data. Intervention adherence was high: participants completed 1.0, 2.9, and 5.7 RBT sessions on average in the 1-, 3- and 6-session, respectively. Functional and questionnaire outcomes were [≥]80% complete at most time points, although follow-up questionnaires at 2 and 4 months met only 74% completeness. Falls monitoring data were available for 30 participants, with 15 falls reported. Estimated sample sizes for a definitive trial using falls as the primary outcome (n=408-782) were not feasible for a single site; alternative primary outcomes (stability following balance perturbations) produced more feasible sample size estimates (n=30-72). Minor adverse events were reported by 1, 2, and 6 participants in the 1-, 3- and 6-session groups, respectively. Conclusions: The modified intervention and assessment procedures were feasible; however, a definitive single-site trial using falls as the primary outcome is not feasible. Stability-based outcomes may support a more feasible future trial. Trial registration: clinicaltrials.gov, NCT04219696