Low Preoperative Exercise Tolerance Predicts Impaired Skeletal Muscle Recovery After Kidney Transplantation.

BACKGROUND

Sarcopenia remains a significant concern among kidney transplant recipients even after renal function improves. However, the predictors of impaired muscle recovery are not well established.

METHODS

We retrospectively analyzed 40 adults who underwent living-donor kidney transplantation at Kansai Medical University Hospital between January 2018 and December 2020. Preoperative cardiopulmonary exercise testing (CPX) was used to stratify patients into low-tolerance (anaerobic threshold VO₂ < 11 mL/kg/min and peak VO₂ < 20 mL/kg/min) and normal groups. The skeletal muscle index (SMI) was measured using dual-energy x-ray absorptiometry from baseline to 3 years post-transplantation. Multivariable linear regression and correlation analyses were performed to identify predictors of long-term SMI improvement.

RESULTS

Forty recipients were analyzed, including 12 (30%) in the low-tolerance group. Following transplantation, the median SMI in both groups decreased at 6 months and improved thereafter. However, from 1 year after transplantation onwards, the normal group demonstrated a significant increase in SMI compared with the low-tolerance group. Three years after transplantation, the median SMI in the normal group exceeded pretransplant levels and steadily increased, whereas in the low-tolerance group, there was little improvement and no return to baseline (P ≤ .05). Multivariable analysis identified low preoperative exercise tolerance as an independent predictor of reduced SMI recovery (P ≤ .05). Correlation analysis revealed that preoperative anaerobic threshold VO₂ and peak VO₂ were moderately and significantly associated with 3-year SMI improvement (r = 0.427 and r = 0.607, respectively).

CONCLUSIONS

Low exercise tolerance before kidney transplantation strongly predicts impaired long-term skeletal muscle recovery. Cardiopulmonary exercise testing-based risk assessment may help identify candidates who could benefit from tailored perioperative rehabilitation strategies to enhance functional outcomes.