A 10-Year Retrospective Review of Nephrolithiasis in the Navy and Navy Pilots

Little is known about the incidence of nephrolithiasis in the U.S. Navy, and Navy pilots must be kidney stone-free and are often referred for treatment of small asymptomatic stones. The primary objectives of this study were to determine the incidence of nephrolithiasis, CT scans performed, proportion undergoing treatment, and incidence of stone-related mishaps of Navy pilots compared with other Navy personnel.

We performed a retrospective study of all Navy service members from 2002-2011 for nephrolithiasis (based on ICD-9 stone codes) to determine the above rates, and reviewed Naval Safety Center (NSC) data for a history of accidents associated with nephrolithiasis. Rates of disease were calculated using person-years of follow-up, and inferential statistics utilized both univariable and multivariable analyses.

We evaluated 667,840 Navy personnel with 3,238,331 person-years of follow-up. The annual incidence of nephrolithiasis was 240 per 100,000 with a 5-year recurrence rate of 35.3%. In multivariable analysis, pilots had similar incidence and treatment rates for nephrolithiasis as the overall Navy population. Women had a higher incidence of nephrolithiasis compared with men (OR 1.17; p <0.0001). The rate of CT scans was lower for pilots than for the rest of Navy (39 vs 66 per 10,000; p <0.0001). There were no recorded accidents associated with kidney stones.

Navy pilots had similar incidence of nephrolithiasis and were no more likely to undergo a surgical procedure. Given no accidents associated with nephrolithiasis, this study suggests reconsideration of current military policies necessitating pilots to be completely stone-free.

The Journal of urology. 2017 Feb 21 [Epub ahead of print]

James H Masterson, Christopher J Phillips, Nancy F Crum-Cianflone, Robert J Krause, Roger L Sur, James O L'Esperance

Division of Urology, Naval Hospital Yokosuka, Yokosuka, Japan. Electronic address: ., Deployment Health Research Department, Naval Health Research Center, San Diego, California., Infectious Diseases, Naval Medical Center San Diego and Scripps Mercy Hospital, San Diego, California., Senior Medical Officer, USS George Washington (CVN 73)., Department of Urology, University of California San Diego Health, San Diego, California., Department of Urology, Naval Medical Center San Diego, San Diego, California; Uniformed Services University of the Health Sciences, Bethesda, Maryland.