Moderate-intensity endurance-exercise training in patients with sickle-cell disease without severe chronic complications (EXDRE): an open-label randomised controlled trial.

BACKGROUND: Exercise could be a triggering factor for vaso-occlusive crises in patients with sickle-cell disease. We aimed to investigate whether a patient-adapted training programme of moderate endurance exercise could be safe and beneficial for patients with sickle-cell disease. METHODS: We did a multicentre, prospective, open-label, randomised controlled trial at four university hospitals in France. Eligible patients were older than 18 years, with an HbSS or S/ß0-thalassaemia genotype, and with no severe chronic complications. All patients underwent cardiopulmonary exercise tests (CPETs) on a stationary bicycle with cardiac, pulmonary, laboratory, and muscle parameter evaluations at the start and end of the study period. We randomly assigned patients (1:1) to the training group (three 45-min exercise sessions per week, for 8 weeks) or the control group (no lifestyle changes) using a central computer-generated randomisation list. During baseline evaluation, patients and researchers were masked to group assignment; randomisation was done after completion of the baseline evaluation to minimise bias. The primary outcome was difference in power output at a blood lactate concentration of 4 mmol/L during CPET between baseline and the end of the 8-week training period. Patients were analysed on a per-protocol basis, excluding those who missed more than 20% of the training sessions or had other major protocol violations. This trial is registered with ClinicalTrials.gov, number NCT02571088, and is completed. FINDINGS: Between Sept 8, 2014, and Dec 11, 2015, 40 patients were enrolled (20 to each group). After exclusion of seven patients (one pregnancy, one appendicitis, one protocol violation, two lost to follow-up, and two incompatibilities with work schedule), 33 patients were analysed (15 in the training group, 18 in the control group). At the 8-week follow-up, the absolute change from baseline in mean power output at 4 mmol/L blood lactate was 7·2 W (SD 8·7) in trained patients (from 70·4 W [SD 16·2] at baseline to 77·6 W [15·1] at end of intervention) compared with -0·3 W (9·4) in controls (from 66·2 W [13·8] to 65·9 W [15·6]; mean difference between groups 7·3 W [95% CI 0·7-13·8], p=0·031). No adverse events requiring hospital admission occurred in the training group, whereas five occurred in the control group: four (20%) vaso-occlusive crises (one complicated by an acute chest syndrome), and one (6%) viral infection with isolated chest pain (hazard ratio 0·143 [95% CI 0·024-0·827; p=0·029). INTERPRETATION: Moderate-intensity endurance-exercise training seems to be safe for adults with sickle-cell disease without severe chronic complications and significantly improved their functional capacity, especially for exercise levels close to those needed for daily activities. Our findings support consideration of endurance-exercise training as a novel therapeutic strategy for patients with sickle-cell disease. FUNDING: Société Française de Cardiologie and Institut National du Sport, de l'Expertise et de la Performance (INSEP).