Emergency department visits in the United States for upper urinary tract stones: trends in hospitalization and charges.

PURPOSE: Using the Nationwide Emergency Department Sample (NEDS) we examined trends in visits, hospitalization and charges for patients with upper urinary tract stones who presented to the emergency department in the United States.

MATERIALS AND METHODS: All visits with a primary diagnosis of kidney calculus (ICD-9-CM code 592.0), ureter calculus (592.1) or urinary calculus unspecified (592.9) were extracted from NEDS between 2006 and 2009. A weighted sample was used to calculate incidence rates. Temporal trends were quantified by the estimated annual percent change. Patient and hospital characteristics associated with hospitalization were evaluated using logistic regression models adjusted for clustering.

RESULTS: Between 2006 and 2009 there were 3,635,054 emergency department visits for upper urinary tract stones. The incidence increased from 289 to 306/100,000 individuals. More men visited than women but women showed significant increases in visits (estimated annual percent change 2.85%, p = 0.018). Total monthly emergency department visits ranged from 5.8% in February to 8.4% in August. Overall 12.0% of patients were hospitalized and the hospitalization rate remained stable (estimated annual percent change -1.02%, p = 0.634). Patients were more likely to be hospitalized if they were female, more ill, seen at an urban teaching or low volume hospital, or had Medicaid or Medicare (each p <0.001). Sepsis was associated with the highest likelihood of hospital admission (OR 69.64, p <0.001). In 2009 charges for emergency department visits increased to $5 billion (estimated annual percent change 10.06%, p = 0.003).

CONCLUSIONS: Women showed significant annual increases in emergency department visits for upper urinary tract stones. While emergency department charges increased substantially, hospitalization rates remained stable. Greater use of computerized tomography and medical expulsive therapy could be the reasons for this observation, which warrants further study.