Epidemiology of Urolithiasis in Japan

Summary

Retrospective nationwide surveys of urolithiasis in Japan were conducted in 1955, 1966, 1979, 1990. and 1999, and covered nearly all the urologists practicing in Japan. In the years of interest, all outpatient visits to urologists which resulted in a diagnosis of urinary tract stones were enumerated, irrespective of admission or treatment. A comprehensive review of these surveys has shed light on the changing pattern of urolithiasis in Japan during the 20th century.

Upper urinary tract stones, which accounted for 40%–60% of cases until 1945, have steadily increased to 97% in 1995. Male preponderance decreased from 7:1 in 1935 to 2.5:1 in 1965 and thereafter. The annual incidence (per 100000) of upper urinary tract stones has steadily increased from 43.7 in 1965 to 80.9 in 1995. This steady increase over the past 30 years will continue in the near future, but it is still lower than that in the United States. The life-long risk of upper urinary tract stones in 1995 was estimated to be 9.0% for men and 3.8% for women. Lower urinary tract stones are predominant in men ≥60 years of age. The annual incidence of lower urinary tract stones has decreased from 37.2 to 27.0 in men (≥60 years old) and increased from 2.4 to 4.8 in women (≥60 years old). Stone composition recorded by infrared spectroscopy showed that an increase in calcium oxalate and uric acid stones and a decrease in calcium phosphate and infection stones is a phenomenon which is common to both upper and lower urinary tract stones.