Stone disease: Not just a problem in men anymore?

The prevalence of women being discharged for stone disease has increased in recent years, according to research presented here yesterday. The rate of discharges for men with stone disease over the same period increased slightly for renal calculi and decreased in the case of ureteral calculi.

"There's a significant amount of evidence which indicates there may be some changes going on," said lead author Charles D. Scales, Jr, MD, a research associate in the division of urology at Duke University Medical Center, Durham, NC. "There are a number of lifestyle and dietary factors that clearly impact the presence of stone disease. And I believe that these features may be causing these underlying changes we're seeing in the data."

Dr. Scales, working with senior author Glenn M. Preminger, MD, and colleagues, used data from the Nationwide Inpatient Sample, a stratified 20% sample of inpatient discharges from U.S. community hospitals for the years 1997 through 2002. An estimated one million discharges for stone disease occurred during the study period. Of those, 31% were for renal stones and 69% were for ureteral stones; 59% of the study cohort was male, and the mean age of the patients was 48 years.

Researchers found that the male to female ratio for stone disease decreased from 1.7 in 1997 to 1.3 in 2002.

Overall, the number of ureteral stone discharges was fairly constant, while renal stone discharges increased by 18.9%. For ureteral calculi, discharges for males decreased by 9.8%, while discharges for females increased by 19.2%. For renal calculi, discharges for males increased by 12.2%, and discharges for females increased by 21%. Remarkably, the number of discharges for renal calculi was equal among males and females in 2002.

The researchers also analyzed population-adjusted discharge rates. They found a slight, statistically insignificant decrease in ureteral calculi.

"Population-adjusted renal calculi discharges, however, increased by more than 14% during the study period," Dr. Scales said. "The increase in renal calculi discharges was accounted for by a small increase in the rate of discharges for males, while females had a 21.5% increase in the rate of discharges for renal calculi."