Beyond Prevalence: Annual Cumulative Incidence of Kidney Stones in the United States

Purpose: It is well documented that the prevalence of nephrolithiasis is increasing in adults in the United States over time. Approximately 11% of men and 7% of women have reported a lifetime history of nephrolithiasis in cross-sectional studies. However, the burden of acute management may be better assessed from annual cumulative incidence. This accounting of new stone occurrences, however, is not well described on a national scale. Materials and Methods: The Medical Expenditure Panel Survey is a set of large-scale health care utilization surveys of families, individuals, their health care providers and employers, with surveys administered every 6 months for the duration of each individual's 2-year panel. We queried the survey data of adult participants between 2005 and 2015, with analysis conducted with provided weights and strata to allow our findings to be representative of the civilian noninstitutionalized U.S. adult population. Those with diagnosed renal or ureteral calculi as noted by ICD-9 codes were included as our incident stone formers. Results: In 2005, the mean age of stone formers was 45 years. Of stone formers 52.2% were male, 91% were White and 47.6% were in the Southern U.S. The incidence of stone occurrences was 0.6% (177/33,961 individuals, weighted to represent population of 1,923,322/296,185,002 individuals). By 2015, the mean age was 51.7 years, with 52% male, 83% White and 38.2% residing in the Southern U.S. Between 2005 and 2015, the overall incidence increased from 0.6% to 0.9% (p <0.001). Conclusions: Based on this large-scale, nationally representative analysis of adults in the United States, the estimated annual cumulative incidence of stone occurrence is approaching 1%. Moreover, this incidence appears to be increasing over time, rising from 0.6% in 2005 to 0.9% in 2015. These data may help to better anticipate the need for urological care for stone disease and direct resource distribution.