Chronic kidney disease perspectives in Japan and the importance of urinalysis screening

There are racial differences in primary renal diseases for end-stage renal disease (ESRD) and the incidence and prevalence of cardiovascular disease (CVD). To reduce the number of patients with both ESRD and CVD, an effective screening method for CKD should be established. In Japan, screening with the urine dip-stick test for proteinuria has been used since 1972 targeting every child and worker and since 1983 for every resident over 40 years old. There are several reasons for continuing this screening program. First, the positive rate of proteinuria is high in the Japanese general population, especially subjects with neither hypertension nor diabetes. Most of these subjects have no symptoms, and the only sign of renal disease is asymptomatic urinary abnormalities. Second, the prevalence and incidence of glomerulonephritis, especially IgA nephropathy, are high in the Japanese and Asian races, and urinalysis is the only method for early detection of chronic glomerulonephritis. Third, 10-year survival of the ESRD patients due to glomerulonephritis was approximately twice that of ESRD patients due to diabetes and nephrosclerosis. Consequently, reducing the incidence of ESRD due to glomerulonephritis is one of the best ways to reduce the prevalence of ESRD. Furthermore, higher incidence of ESRD in Asian races than in Caucasians was reported. Proteinuria is known to be the best predictor for reducing renal function, and the urine dip-stick test for proteinuria is less expensive and is cost-effective. For an effective screening strategy to reduce the ESRD population in Japanese and Asians, universal screening with the urine dipstick test for proteinuria could be one solution.