Safety, adherence and efficacy of exercise training in solid-organ transplant candidates: a systematic review

Background - Patients awaiting solid-organ transplantation may be encouraged to undertake exercise training to improve pre- and post-transplant outcomes. However, the safety, adherence and efficacy of exercise training in this population remain unclear. Methods - All randomized, non-randomized and non-controlled trials of exercise training interventions in solid-organ transplant candidates were included. The Cochrane risk of bias tool and a modified Newcastle-Ottawa scale were used to assess procedural quality. Safety was defined as the number of reported adverse events during exercise training. Adherence was evaluated from session attendance, and efficacy as changes in cardiorespiratory fitness (CRF), exercise capacity, muscular strength, health-related quality of life (HR-QoL) and lung function. Results - Eleven studies involving 874 patients were included: four randomized controlled, one non-randomized controlled and six non-controlled trials. Six studies included heart transplant candidates and five involved patients awaiting lung transplantation. Three trials included aerobic-only training, one incorporated resistance-only exercise and seven combined modalities. Twelve adverse events were reported with four due to exercise, although methods to collect these data were often omitted. Exercise adherence ranged from 82.5–100%, but was poorly described. No significant between–group changes attributable to exercise training were demonstrated. However, significant within-group improvements in CRF, exercise capacity, muscular strength, lung function and HR-QoL were observed. Conclusions - Patients awaiting heart or lung transplant appear to tolerate exercise training despite the larger number of adverse events compared to other high-risk populations. Exercise training demonstrated within-group benefits for several outcomes, with no significant between-group differences. Randomized controlled trials with sufficient statistical power are required for all solid-organ transplant candidates.