Provider variation in the quality of metabolic stone management

Urinary stone disease is a chronic condition for which secondary prevention (dietary and medical therapy guided by 24-hour urine collection results) has an important role. Assessing the response to these interventions with followup testing is recommended and yet to our knowledge provider compliance with these guidelines is unknown.

Using Litholink® files from 1995 to 2013 we identified adults with urinary stone disease who underwent metabolic evaluation and the providers who ordered the evaluation. By focusing on patients with an abnormality on the initial collection we determined the proportion who underwent a followup test within 6 months of the initial test. Multilevel modeling was done to quantify variation in followup testing among providers after accounting for various patient and provider factors.

A total of 208,125 patients had an abnormality on the initial collection, of whom only 33,413 (16.1%) performed a repeat collection within 6 months. While most variation in followup testing was attributable to the patient, the provider contribution was nontrivial (18.0%). The specialty of the ordering provider was important. Patients who saw a urologist had 24% lower odds of repeat testing compared to those who saw a primary care physician (OR 0.76, 95% CI 0.67-0.86, p <0.001).

Followup testing is uncommon in patients with an abnormal initial 24-hour urine collection. Given the observed provider variation, efforts to educate providers on the value of followup testing are likely to have salutary effects on patients with metabolic stone disease.