Introduction: Contemporary guidelines for the prevention of urinary stone disease (USD) recommend that a 24-hour urine collection be analyzed with a minimum set of urinary analytes. However, unlike a comprehensive metabolic panel, there is no approved set of measurements that a provider can easily order, potentially leading to incomplete testing. To examine this possibility, we analyzed data from the Veterans Health Administration (VHA).
Methods: Using files from the VHA Corporate Data Warehouse (2012 to 2019), we identified a cohort of patients, who primarily use the VHA for their healthcare needs, with at least two outpatient or one surgical encounter for USD. Next, we determined the subset who performed a 24-hour urine collection within 12 months of their index USD encounter. Through Logical Observation Identifiers Names and Codes, we evaluated each collection’s completeness, defined as including all of urine volume, calcium, oxalate, citrate, uric acid, and creatinine. We then fit a multilevel logistic regression model with random effects for facility to evaluate factors associated with testing completeness.
Results: In total, 15,660 patients performed a 24-hour urine collection, but nearly half of tests (46.1%) were incomplete. The percentage of complete collections increased over time (43.1% in 2012 to 63.2% in 2019). The facility where a patient was seen mattered. The Figure shows wide variation in unadjusted rates of 24-urine completeness among facilities, ranging from as low as 0% to as high as 98.1%. In the adjusted analysis, there was considerable between-facility variation in 24-hour urine completeness (Median Odds Ratio, 4.98; 95% CI, 3.50-5.50). Collectively, individual facilities contributed almost 46% (ICC, 0.46; 95% CI, 0.35-0.49) to the observed variation in 24-hour urine completeness. Older age, Hispanic ethnicity, and presence of conditions associated with high risk of USD recurrence were significantly associated with a lower odds, whereas female sex and more recent calendar year were associated with a higher odds, of complete testing.
Conclusions: Nearly half of 24-hour urine tests obtained for prevention of USD do not have the minimum set of urinary analytes. These data suggest that addressing the facility level variation in testing completeness may improve the quality of USD care within VHA facilities.
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