Changes in gender distribution of urinary stone disease

Abstract

Objectives: To explore using population-based data the extent to which gender-specific rates of stone disease are changing. Historically, stone disease has been more common among men than women. However, differential changes in dietary intake patterns, fluid intake, and obesity in men and women may cause shifts in stone disease incidence and prevalence.

Methods: The State Ambulatory Surgical Database and the State Inpatient Databases were queried for procedures related to renal colic or urolithiasis. Population-based rates of utilization were calculated for the years 1998-2004 by gender. Poisson regression models were fit to measure changes in utilization rates over time.

Results: Of the 107,411 discharges for stone disease, 41,272 (38%) occurred in women. Service utilization increased in both men and women (86.6-105.5 and 42.5-64.4 per 100,000; P <.01 in both). However, the growth rate in women outpaced men (P <.01). Rates of outpatient (57.2-65.8 and 27.0-38.9 per 100,000; P <.01) and ambulatory surgery center utilization (6.4-17.7 and 2.9-9.3 per 100,000 men and women; P <.01) increased significantly in men and women, but inpatient utilization only increased in women (12.5-16.3 per 100,000; P <.01).

Conclusions: Resource utilization for stone disease continues to increase. Most of this increase appears to be due to an increase in disease among women. Increasing obesity, dietary changes, or decreased fluid intake may be contributing to the rapid increase in stone disease treatments in women.

Figure 1. Overall Admissions for Upper Urinary Tract Stone Disease

Admissions for urinary stone disease increased from 129.1 to 169.9 per 100,000 over the six years of the study (p <0.01). Both men and women increased utilization (p<0.01 for both groups). However, the rate of growth in women was greater than in men (p<0.01).

Figure 2. Inpatient Admissions for Upper Urinary Tract Stone Disease

Inpatient admissions in women increased (p<0.01). No increase was found in men (p = 0.7964). The increase in women was significantly greater than in men (p = 0.01).

Figure 3. Hospital Outpatient Department Utilization for Upper Urinary Tract Stone Disease

Outpatient admissions in both women and men grew significantly (p < 0.01 women and p = 0.01 men). Utilization grew faster in women compared to men. (p < 0.01).

Figure 4. Ambulatory Surgery Center Utilization for Upper Urinary Tract Stone Disease

ASC utilization grew significantly in both women and men (p<0.01 for both). No evidence exists for differential rates of growth among male and female stone patients for use of ASCs (p = 0.44).