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PURPOSE: The incidence and prevalence of urolithiasis are increasing but clinicians also have the impression that gender and age distributions of stone formers are changing. Moreover, regional differences in stone occurrence and composition have been observed. We analyzed such trends based on a large series of urinary stone analyses. MATERIALS AND METHODS: A total of 224,085 urinary stone analyses from 22 German centers were evaluated to determine the incidence of stone composition and identify age and gender distributions from 1977 to 2006. A subset of 58,682 stone analyses from 1993 to 2006 was available to identify regional differences in stone composition in Germany. RESULTS: Calcium containing calculi were most common in each gender. The overall male-to-female ratio of 2.4:1 increased from 1977 (1.86:1) to 2006 (2.7:1). The predominance of male calcium stone formers was even higher among elderly patients with a 3.13:1 ratio at ages 60 to 69. Since 1997, we observed a tendency toward an increasing incidence in middle-aged patients at ages 40 to 49 years. While the rate of infection stones constantly decreased, the incidence of uric acid calculi remained stable with an overall rate of 11.7% in males and 7.0% in females with a peak at higher ages. Cystine stones remained rare at 0.4% in males and 0.7% in females. In terms of regional analyses we noted great variation in stone composition in the 2 genders. Uric acid stones were more common in the eastern and southern regions but infection stones were mostly seen in eastern regions. CONCLUSIONS: In what is to our knowledge the largest series of stone analysis reported to date we identified an age and gender relationship of stone formation and composition. Regional variations are common and underline the influence of living habits, diet and standard of medical care on urinary stone formation.
Knoll et al. (Wed,) studied this question.