Incidence of urolithiasis leading to hospitalization in Finland

The study population consists of 2304 urolithiasis patients discharged from all hospitals in 21 central hospital districts in 1970. The incidence rate was 50 per 100 000 inhabitants per year, 74 for men and 27 for women. The age distribution resembles the Gaussian curve, with a peak between 45 and 49 years for men and between 50 and 54 years for women. The male/female ratio was 2.7 in the entire material, about 1 in the age group 0--24 years, about 3 in the age group 25--74 years and about 1.5 in patients 75 years or older. The standardized incidence was highest in Southeastern Finland and in the archipelago of Aland, and lowest in the coastal area of Southwestern Finland. In the area with high incidence, the age distribution of urolithiasis patients differed from that in the rest of the country: in the age groups over 40 the incidence of urolithiasis did not appear to decrease. This difference was attributed to some lifelong environmental exposure. The standardized incidence of urolithiasis leading to hospitalization was higher among urban than rural residents. Seasonal variation in the hospital admissions for urolithiasis was not evident, temporal patterns of admissions were, however, dissimilar in urban and rural areas, and might reflect differences in the physical activities of urban and rural populations.