Relationship Between Baseline and Longitudinal Self-Reported Physical Function and Cardiorenal Outcomes in CKD: Findings From the CRIC Study

RATIONALE & OBJECTIVE: Physical function is essential for independent living and good health. The trajectory of physical function and its association with important clinical outcomes is understudied in chronic kidney disease (CKD). We describe the associations of baseline and longitudinal self-reported physical function with cardiorenal outcomes among individuals with CKD. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: Participants of the multicenter Chronic Renal Insufficiency Cohort (CRIC) Study. EXPOSURE: Physical Component Summary (PCS) score and PCS slope. OUTCOME: Incident heart failure (HF), incident end-stage kidney disease (ESKD), and all-cause mortality. ANALYTICAL APPROACH: Multivariable adjusted Cox regression models examined associations of baseline PCS score with outcomes and in separate models assessed associations of PCS slope with outcomes. Effect modification was assessed by age, sex, race, and estimated glomerular fitration rate groups. RESULTS: Lower baseline PCS scores (per 10 points) were independently associated with higher risks of incident HF (HR, 1.21 95% CI, 1.11-1.32) and all-cause mortality (HR 1.21 95% CI, 1.16-1.26) but not with incident ESKD (HR, 0.98 95% CI, 0.93-1.04). PCS change (per 4 points annually) was also independently associated with higher risks for all 3 outcomes: incident HF (HR, 1.22 95% CI, 1.05-1.42), all-cause mortality (HR, 1.22 95% CI, 1.13-1.32), and incident ESKD (HR, 1.11 95% CI, 1.01-1.22). LIMITATIONS: Residual confounding, selection bias, and linearity assumption. CONCLUSIONS: Among individuals with CKD, baseline self-reported physical function was significantly associated with increased risk of incident HF and mortality after full adjustment. In addition, longitudinal changes in self-reported physical function were associated with incident HF, incident ESKD, and mortality, even after accounting for baseline self-reported physical function. These findings support monitoring for and testing of early interventions to preserve physical function and potentially prevent or delay adverse outcomes. PLAIN-LANGUAGE SUMMARY: People with chronic kidney disease (CKD) often experience a decline in physical function, but it is unclear how the decline impacts important outcomes in CKD. This study explored how both initial physical function and changes over time relate to important outcomes in CKD, including heart failure, kidney failure, and death. We found that people who rated their physical function lower or whose physical function declined over time were more likely to experience heart failure, kidney failure, and death. These patterns held true even after accounting for other heatlh conditions. These findings suggest that early interventions to preserve physical function could potentially prevent or delay these outcomes in patients but should be tested.