Background: Uric acid may be a true mediator of renal disease and progression. However, epidemiological evidence for the significance of serum uric acid levels on the risk for developing end-stage renal disease (ESRD) is scarce in a setting of community-based screening.
Methods: Participants in a 1993 mass screening conducted by the Okinawa General Health Maintenance Association in Okinawa, Japan, were investigated: 48,177 screenees (22,949 men, 25,228 women) older than 20 years for whom serum uric acid data were available were studied. All dialysis patients treated in Okinawa were independently registered in the Okinawa Dialysis Study registry. Participants in the 1993 screening who later entered a dialysis program were identified by using 2 computer registries. The cumulative incidence of ESRD was calculated according to quartiles of baseline serum uric acid levels for each sex. The significance of hyperuricemia (serum uric acid level > or = 7.0 mg/dL [> or =416 micromol/L] in men and > or = 6.0 mg/dL [> or =357 micromol/L] in women) for the risk for developing ESRD was evaluated by means of the Cox model after adjusting for age, blood pressure, body mass index, proteinuria, hematocrit, and total cholesterol, triglyceride, fasting blood glucose, and serum creatinine levels.
Results: Mean serum uric acid level was 6.4 +/- 1.4 (SD) mg/dL (381 micromol/L) in men and 4.8 +/- 1.1 mg/dL (286 micromol/L) in women. Prevalences of hyperuricemia were 31.9% in men and 13.6% in women. By the end of 2000, a total of 103 screenees (53 men, 50 women) entered dialysis programs. Calculated incidences of ESRD per 1,000 screenees were 1.22 for men without hyperuricemia and 4.64 for men with hyperuricemia and 0.87 for women without hyperuricemia and 9.03 for women with hyperuricemia. Adjusted hazard ratios for hyperuricemia were 2.004 (95% confidence interval, 0.904 to 4.444; P = not significant) in men and 5.770 (95% confidence interval, 2.309 to 14.421; P = 0.0002) in women.
Conclusion: Screenees with hyperuricemia were associated with a greater incidence of ESRD. Hyperuricemia (serum uric acid > or = 6.0 mg/dL [> or =357 micromol/L]) was an independent predictor of ESRD in women. Strategies to control serum uric acid levels in the normal range may reduce the population burden of ESRD.