Association between physical activity and mortality in the Japanese general population with mild to moderate impaired renal function: the Jichi Medical School (JMS) cohort study.

BACKGROUND

The association between physical activity volume or intensity and mortality in general population with impaired renal function is unclear. We assessed these relationships among Japanese residents with impaired renal function.

METHODS

We analyzed 638 individuals with estimated creatinine clearance below 60 ml/min in the Jichi Medical School cohort study. Exposures included the daily amount of physical activity converted to the physical activity index (PAI) used in the Framingham study and the activity time for each intensity. Physical activity intensity was classified into sedentary and nonsedentary. Nonsedentary activity was further divided into light-intensity and moderate-to-vigorous physical activity (MVPA). The outcome was all-cause mortality. Quartiles of the exposures were created, and hazard ratios (HRs) were calculated using the Cox proportional hazards model.

RESULTS

The mean age of the subjects was 63.3 years, and 72.4% were female. In total, 172 deaths were registered during 11,567 person-years. No significant association was found between PAI and mortality. A significant association was found between long sedentary time and increased mortality (p = 0.042). Regarding nonsedentary activity, the HRs [95% confidence intervals (CIs)] for Q2, Q3, and Q4 versus Q1 were 0.85 (0.55-1.31), 0.67 (0.41-1.08), and 0.90 (0.54-1.45), respectively. In the subdivided analysis for light-intensity activity, the HRs (95% CIs) of Q2, Q3, and Q4 versus Q1 were 0.53 (0.33-0.84), 0.51 (0.34-0.82), and 0.57 (0.34-0.96), respectively. No significant association was found between MVPA and mortality.

CONCLUSIONS

Nonsedentary activity, especially light-intensity activity, significantly reduced mortality among residents with impaired renal function.