Physical Function Decline Among Adults With Moderate-to-Severe CKD

Individuals with chronic kidney disease (CKD) experience substantial impairments in physical function that are linked to disability and mortality, yet the trajectory of functional decline across stages of CKD remains poorly characterized. We examined baseline levels and longitudinal changes in objective physical function in a large prospective CKD cohort.

At 2-to-3-year intervals, the Chronic Renal Insufficiency Cohort (CRIC) Study measured grip strength (kg) and the Short Physical Performance Battery (SPPB; range: 0-12), including gait speed (m/s), 5-repetition chair stand time (s), and balance. Linear mixed-effects models were used to estimate annual changes in physical function adjusted for age, sex, estimated glomerular filtration rate (eGFR), body mass index, diabetes, cardiovascular disease, education, hemoglobin, physical activity, and depressive symptoms. Baseline physical function was compared with age-matched population reference values and categorized using published impairment thresholds.

Among 3955 participants (mean age: 62 ± 10 years, mean eGFR: 47 ± 20 ml/min per 1.73 m², 43% female), baseline impairment was common: 33% gait speed, 70% chair stands, 43% grip strength, and 50% SPPB. Compared with normative values, physical function was up to 75% worse depending on age and test. Over a median follow-up of 8.5 years, older age and lower eGFR were associated with steeper declines across measures. After full adjustment, each 15 ml/min per 1.73 m² lower eGFR was associated with declines equivalent to approximately 3 to 5 additional years of aging.

Physical function impairment is common and progressive in moderate-to-severe CKD, with kidney dysfunction contributing substantially to functional decline beyond chronological aging. Although per-unit changes are modest, their cumulative impact over time may be clinical meaningful. These findings support the evaluation of objective physical function measures in CKD and the development and testing of interventions to preserve function and independence.