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Kidney Week

Abstract: TH-OR30

Factors Associated with Sex Differences in the Risk of Kidney Stones

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Ferraro, Pietro Manuel, Università Cattolica del Sacro Cuore, Rome, Rome, Italy
  • Taylor, Eric N., VA Maine Healthcare System, Augusta, Maine, United States
  • Curhan, Gary C., Brigham and Women's Hospital Channing Division of Network Medicine, Boston, Massachusetts, United States
Background

Kidney stone disease is a highly prevalent condition. Men are at higher risk of developing stones compared with women, however recent data suggest a changing epidemiology with women being relatively more affected than in the past. The reasons for such differences and changes over time are not clear.

Methods

We analyzed the association between sex and incident kidney stones using data from three large cohorts. Kidney stone incidence rates for men and women overall and across categories of age and calendar time were computed and hazard ratios (HRs) and 95% confidence intervals (CIs) generated with age-adjusted Cox proportional hazards regression models. Mediation analysis was performed to estimate the amount of excess risk for men explained by established risk factors, including waist circumference, history of high blood pressure, history of diabetes, use of thiazides, dietary intakes. Twenty-four hour urine composition was also examined.

Results

The analysis included data from 268,553 participants, contributing 5,872,249 person-years of follow-up, during which 10,302 incident stone events were confirmed. The incidence rate of kidney stones was 271 and 159 per 100,000 person-years for men and women, respectively. The age-adjusted HR for men compared with women was 2.32 (95% CI 2.20, 2.45). Part of the difference in rates was explained by the risk factors included in the analysis, mainly waist circumference and fluid intake. The risk of stones was consistently higher across categories of age among men compared with women (HRs ranging from 2.02 to 2.76). Regarding calendar time, the risk remained higher among men, but tended to decrease over time while it increased among women, resulting in a 48.1% decrease for after 2009 compared with before 1990. Supersaturations for calcium oxalate and uric acid were higher among men, primarily because of 26.3% higher urine oxalate, 16.3% higher urine uric acid, 23.5% higher urine phosphate and more acidic urine. Urine volume, citrate, oxalate and pH contributed significantly toward an increased risk among men.

Conclusion

The risk of kidney stones is higher among men compared with women. This difference is only partly explained by modifiable lifestyle risk factors; however, differences in urine chemistries explain a substantial fraction of the excess risk.

Funding

  • Other NIH Support