To investigate the distribution characteristics and changing tendency of urinary tract stones.

From January 2011 to May 2017, clinical data of 15 269 patients treated in our center was retrospectively reviewed. The stone components were detected by the automatic stone infrared spectroscopy system and the predominant components were recorded. There were 9 019 male patients and 6 250 female patients. The patients were divided into four groups according to their age, including group A≤18 years; group B 19-40 years; group C 41-60 years; and group D>60 years. Compared the distribution characteristics of urinary tract stones of patient in different groups of sex, age and calendar year.

Calcium oxalate stones were more prevalent in males than females [6 221(69.0%)vs.3 582(57.3%), P<0.001], but calcium phosphate stones [210(3.4%)vs.210(2.3%)], magnesium ammonium phosphate stones [230(3.7%)vs.165(1.8%)] and carbonate apatite stones [1 328(21.3%)vs.1 030(11.4%)] were more common in females than males (P<0.001, respectively). The proportion of uric acid stones in group D [679(20.7%)] was higher than that in group A [23(9.1%)], group B[260(7.9%)], group C [1 163(13.8%)] (P<0.001, respectively). The peak of carbonate apatite stones was showed in group B [652(19.7%)] (P<0.001, respectively). Ammonium urate stones [9(3.5%)] and cystine stones [36(14.2%)] were more frequent in group A(P<0.001, respectively). In adults, the percentage of uric acid stones increased with age, such as group B [260(7.9%)], group C [1 163(13.8%)], group D [679(20.7%)]. And the carbonated apatite stones decreased with age, such as group B [652(19.7%)], group C [1 270(15.1%)], group D [416(12.7%)](P<0.001, respectively). Further analysis showed the proportion of calcium oxalate (OR=0.944, 95% CI 0.927-0.962, P<0.001), ammonium urate stones (OR=0.854, 95% CI 0.742-0.982, P=0.027) decreased, while calcium phosphate (OR=1.192, 95%CI 1.127-1.261, P<0.001), uric acid (OR=1.042, 95% CI 1.015-1.069, P=0.002) and ammonium magnesium phosphate (OR=1.078, 95% CI 1.019-1.141, P=0.009)stones increased with time.

The distribution of stones was different in genders and age. Calcium oxalate stones were more common in male patients, while ammonium magnesium phosphate and carbonate apatite stones were more common in female patients. Uric acid stones were more frequent in patients older than 60, while carbonate apatite were more frequent in the 19-40 age group. The proportion of calcium oxalate and ammonium urate stones showed a downward trend, whereas calcium phosphate, uric acid and magnesium ammonium phosphate stones increased with time.

Urinary tract stones; Stone compositions; Gender; Age; Calendar year