Prevalence and epidemiological characteristics of urolithiasis in Japan: national trends between 1965 and 2005.

OBJECTIVES: We evaluated the epidemiological details and chronological trends of upper urinary tract stones in Japan using a nationwide survey of urolithiasis.

METHODS: All patient visits to urologists that resulted in a diagnosis of first-episode upper urinary tract stones in 2005 were enumerated irrespective of admission and treatment. The study included all hospitals approved by the Japanese Board of Urology, thus covering nearly all urologists practicing in Japan. We compared the estimated annual incidence according to gender and age with the incidence determined from nationwide surveys between 1965 and 1995.

RESULTS: The estimated annual incidence of first-episode upper urinary tract stones in 2005 was 134.0 per 100,000 (192.0 in men and 79.3 in women). The estimated age-standardized annual incidence of first-episode upper urinary tract stones in 2005 was 114.3 per 100,000 (165.1 for men and 65.1 for women), which represents a steady increase from 54.2 in 1965. The annual incidence has increased in all age groups except during the first 3 decades of life and the peak age for both men and women has also increased.

CONCLUSIONS: The annual incidence of upper urinary tract stones has steadily increased in Japan and this trend will continue in the near future. This probably results from improvements in clinical-diagnostic procedures, changes in nutritional and environmental factors, and general apathy toward metabolic clarification and metaphylaxis.