Twenty-four-hour Urine Testing and Urinary Stone Disease Recurrence in Veterans

To determine whether 24-hour urine testing in Veterans with USD (urinary stone disease) reduces or delays urinary stone recurrence.

Cohort study of national health record data from Veterans Health Administration from 2007 through 2013. We utilized a study population of 130,129 Veterans with USD based on diagnostic or procedural codes and excluded those with USD claims in the 2 years before cohort entry. We then created a propensity-score matched cohort of 14,854 Veterans based on completion of 24-hour urine testing within 6 months of stone diagnosis. Primary outcome was time-to-next clinically significant stone event, defined as an emergency department visit, inpatient admission related to a urinary stone, or urologic stone procedure with 5-year follow up.

Of 14,854 Veterans in the propensity-score matched cohort, 8560 (57.6%) experienced a recurrent USD event. Completion of 24-hour urine testing was associated with a higher risk of developing a second stone event (hazard ratio [HR] 1.17, 95% confidence interval [95% CI] 1.12-1.22). Among Veterans with known recurrent disease, we examined time to a third stone event. In this cohort of 4736 patients, completion of 24-hour urine testing was not associated with a higher risk of developing a third stone event (HR 1.06, 95% CI 0.99-1.12).

Completion of 24-hour urine testing was not associated with a reduction in urinary stone recurrence. These findings challenge the validity of a longstanding recommendation in general medicine, nephrology, and urology practice.