Epidemiology of renal stones in a middle-aged male population.

The natural history of upper urinary tract stones has been studied retrospectively in 49-50 year-old men in an urban population. The prevalence of stones in 2322 men was found to be 13.7%, with the highest incidence of onset of the disease during fifth decade. Recurrences had occurred in 42% of all cases, the frequency increasing with observation time. On some occasion 23% of the patients had been admitted to hospital and 12.3% had been operated on, 94.5% of all stones passed spontaneously. A family history of kidney stones was significantly more common in stone patients than in healthy controls, and patients with a family history of stones were more prone to early and repeated recurrences. It is suggested that the raised incidence of stone disease in some families may be attributed to environmental rather than genetic factors. This could be of importance for prophylaxis. Analysis of hospital admission rates supported previous findings of a steady rise in stone incidence. The advantages of population studies for comparative analyses are pointed out.