The incidence of kidney stones has increased among young patients, especially girls, and among blacks, according to a new study.

Gregory E. Tasian, of the Children’s Hospital of Philadelphia, and colleagues performed a population-based study using U.S. Census data and South Carolina Medical Encounter Data, which capture all emergency department visits, surgeries, and hospital admissions in the state.

Among an at-risk population of 4,625,364 people, 152,925 unique patients received emergency, inpatient, or surgical care for kidney stones during the 1997–2012 study period, Dr. Tasian’s group reported online ahead of print in the Clinical Journal of the American Society of Nephrology. The mean annual incidence of nephrolithiasis increased 1% annually from 206 to 239 per 100,000 persons.

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The researchers observed the greatest increase among 15–19 year olds, in whom the incidence rose 26% per 5 years. In this age group, the incidence increased 23% per 5 years among boys and 28% per 5 years for girls. Adjusting for age and race, the incidence increased 15% per 5 years among females, but remained stable for males, according to the investigators. The incidence among blacks increased 15% more per 5 years compared with whites.

“These changes in incidence resulted in doubling of the risk of nephrolithiasis during childhood and a 45% increase in the lifetime risk of nephrolithiasis for women over the study period,” the authors concluded.

The authors stated that the emergence of nephrolithiasis as a disease that begins in childhood is worrisome because there is limited evidence about how to best treat the disease in children.

Use of South Carolina Medical Encounter Data was a strength of the study because it includes unite patient identifiers and dated encounters for care received at every hospital in the state over a 16-year period. Consequently, the authors were able to describe annual changes in the  distribution and frequency of nephrolithiasis in the population, which are obscured in analyses using the National Health and Nutrition Examination Survey and Healthcare Cost and Utilization Project databases. Among study limitations, the researchers acknowledged that their observations are on the basis of data from a single state and they cannot completely rule out that changes in imaging use contributed to changes in nephrolithiasis incidence.