Incidence of upper urinary tract stone during 15 years in Tajima area, Japan: a hospital-based study

Time trend of incidence of upper urinary tract stone during 15 years was evaluated by hospital-based cohort study in Tajima area, northern part of Hyogo prefecture, Japan, which has only two general hospitals with Department of Urology. Due to isolation in terms of traffic network and geographic circumstances, almost all patients with urinary stone in Tajima area are referred to the two hospitals. During the period 2005–2007, patients of the two hospitals with radiologically proven upper urinary tract stone were included in this study. The survey included the age and gender, location of stones, history of urinary stone, treatment received, and stone composition, if available. Annual incidence of upper urinary tract stone was estimated using the data of population census of Japan 2005 and compared with the data of Tajima during 1991–1993. 1,305 patients were included in this study. Age-adjusted incidence (±95% CI) was 157 (±22.4) for men, and 57 (±12.6) for women, compared with 141 (±20.7) for men, and 63 (±13.4) for women during 1991–1993. In total, 30.7% of patients received interventional treatment including shock wave lithotripsy, endoscopic lithotripsy and open surgery, whereas 25.3% in 1991–1993. Calcium oxalate/phosphate stone was 89.6%, struvite stone was 4.5%, cystine stone was 1.0%, uric acid stone was 4.0%, and others were 1.0%. In Tajima area, incidence of upper urinary tract stone has not changed during 15 years.