Emergency department visits, use of imaging, and drugs for urolithiasis have increased in the United States

Abstract

The occurrence of urolithiasis in the United States has increased; however, information on long-term trends, including recurrence rates, is lacking. Here we describe national trends in rates of emergency department visits, use of imaging, and drug treatment, primarily using the National Hospital Ambulatory Medical Care Survey to describe trends and the National Health and Nutrition Examination Survey to determine the frequency of lifetime passage of kidney stones. Emergency department visit rates for urolithiasis increased from 178 to 340 visits per 100,000 individuals from 1992 to 2009. Increases in visit rates were greater in women, Caucasians, and in those aged 25-44 years. The use of computed tomography in urolithiasis patients more than tripled, from 21 to 71%. Medical expulsive therapy was used in 14% of the patients with a urolithiasis diagnosis in 2007-2009. Among National Health and Nutrition Examination Survey participants who reported a history of kidney stones, 22.4% had passed three or more stones. Hence, emergency department urolithiasis visit rates have increased significantly, as has the use of computed tomography in the United States. Further research is necessary to determine whether recurrent stone formers receive unnecessary radiation exposure during diagnostic evaluation in the emergency department and allow development of corresponding evidence-based guidelines.

Figure 1

Rates of visits per 100,000 US population with a diagnosis of upper tract urolithiasis to US emergency departments: 1992–2009. A weighted least-square regression analysis showed a significant linear trend. Error bars are 95% confidence intervals.

Figure 2

Rates of emergency department visits with a diagnosis of upper tract urolithiasis by season and region, 1992–2009. (a) Seasonal and (b) regional variation of emergency department visit rates with a diagnosis of upper tract urolithiasis per 100,000 population from 1992–2000 to 2001–2009. Spring is March to May, summer is June to August, fall is September to November, and winter is December to February in this study. Error bars are 95% confidence intervals.

Figure 3

Percentage of computed tomography (CT) and X-ray/ultrasound use in upper tract urolithiasis emergency department visits with any imaging used from 1998–2003 to 2004–2009. Error bars are 95% confidence intervals.