Changes in the incidence of lower urinary tract stones in Japan from 1965 to 1995

Background: The changes over time of the annual incidence of lower urinary tract stones in Japan from 1965 to 1995 were analyzed. Methods: Data on lower urinary tract calculi were abstracted from the past three nationwide surveys of urolithiasis, which covered nearly all major ho spitals and urologists in Japan and enumerated all outpatient visits diagno sed as urolithiasis in the years 1965, 1975, 1985 and 1995. Chronological c hanges in the sex- and age-related annual incidences of lower urinary tract stones and stone composition were estimated. Results: Lower urinary tract stones were predominant in men 60 years of age or older. Between 1965 and 1995, the annual incidence has significantly de creased in men greater than or equal to 60 years of age from 37.2 to 27.0 p er 100 000 and significantly increased in women greater than or equal to 60 years of age from 2.4 to 4.8 per 100 000. In men, an increased proportion of uric acid and calcium stones as well as a decreased frequency of infecti on stones is a phenomenon common to upper urinary tract stones. However, in fection and calcium stones have been two major stone types in women. Conclusions: In contrast to upper urinary tract calculi, the incidence of l ower urinary tract stones has decreased over the last 30 years in men great er than or equal to 60 years of age predisposed to this disease.