Exercise Training And Progression Of Chronic Kidney Disease: The GFR-Exercise (GFR-Ex) Randomized Controlled Feasibility Study

Introduction: The GFR-Ex study assessed the feasibility of a 12-month exercise training program to attenuate the rate of decline in isotope-measured (mGFR) and estimated (eGFR) glomerular filtration rate. Methods: In a multicenter feasibility study, people with stage 3–4 chronic kidney disease (CKD) with declining function were randomized to 12 months exercise training (home-based aerobic and resistance program) or control (usual care). Feasibility was assessed by recruitment and retention rates, intervention adherence, and harms. Differences in mGFR between groups at 12 months and between mGFR and eGFR were calculated. Qualitative interviews were used to explore participant experiences. Results: A total of 2,260 patients were screened; 74 participants were randomized (mean age [SD]: 56 [14] years; eGFR: 34 [13] mL/min/1.73 m2; 62% male; 61% white); and 34 completed the study (11 exercise; 23 control). The screening eligibility rate was 11%; consent rate was 48%; 12-month retention rate was 43%; and the median (IQR) exercise sessions completed was 69 (63, 72)%. No exercise-related harms were recorded. The mean mGFR at 12 months was 36.1 (exercise) vs. 33.8 (control); eGFR minus mGFR was −1.6 (95% Cl: −2.6, −0.6) mL/min/1.73 m2. Qualitative interviews identified the importance of peer and professional support for patient engagement and a high level of patient commitment being required for the research procedures. Conclusion: In people with progressive CKD, a 12-month exercise training program was safe and feasible. Exercise tended to attenuate GFR decline, and eGFR agreed well with mGFR. Progression to a definitive trial is warranted, provided modifications are made, including providing patient support and selection of eGFR as the primary outcome.