Introduction: Improved physical function is associated with increased survival in the general population. Little is known about whether physical function improves following kidney transplant. The aim of this study was to assess change in physical function after kidney transplant using performance-based measures.

Methods: We conducted a prospective study involving all recipients of living donor kidney transplants at our center from 2012 until 2014. Physical function was measured pre-transplant and 4-months post-transplant using tests of dominant hand grip strength, balance, chair rise time and gait speed. Meaningful improvement in gait speed was defined as ≥ 0.10 m/sec increase following transplant. Measures of balance, chair rise time and gait speed were also combined in the Short Physical Performance Battery (SPPB), a composite measure of lower extremity function (score range 0-12, higher score indicates better physical function).

Results: A total of 140 patients underwent pre-transplant testing of whom 113 patients also underwent post-transplant testing. Mean age was 51 ± 15 years, 61% were male, 91% were Caucasian, and 21% had diabetes. Low pre-transplant gait speed (<1.0 m/sec) was observed in 16% of patients and was associated with recipient age (OR 1.58 per 10 year increase, CI 1.09-2.42, p=0.02) and history of dialysis (OR 3.76, CI 1.37-11.18, p=0.01) (multivariate Cox). Following transplant, physical performance improved significantly, including measures of grip strength (32.97 to 34.51 kg, p=0.0003), chair rise time (9.11 to 8.10 sec, p<0.0001), gait speed (1.18 to 1.25 m/sec, p<0.0001) and SPPB score (11.05 to 11.43 points, p=0.002) (paired t-test). Meaningful improvement in gait speed was seen in 35% of patients (n=39). After adjusting for pre-transplant gait speed, 4-month eGFR was significantly associated with meaningful improvement in post-transplant gait speed (OR 1.41 per 10 ml/min/1.73 m² increase, CI 1.04-1.97, p=0.03), whereas recipient age, diabetes and steroid use were not.

Discussion: Although small improvements in physical function are seen following living donor kidney transplant, only one-third of recipients experience meaningful improvement in gait speed. Further research is needed to determine whether physical activity interventions can improve physical function in high-risk patients.

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