Claims-based Approach to Defining Renal Colic Episodes: Implications for Researchers, Providers, and Policymakers

To define renal colic episodes more accurately using a novel claims-based method and evaluate how clinical and nonclinical factors, including insurance type, affect rates of surgical intervention and Emergency Department (ED) revisits, as well as episode-related expenditures. Traditional fixed-window episode definitions may misclassify care duration and intensity, limiting their utility in assessing real-world utilization.

We analyzed 2016-2019 claims data from North Carolina Medicaid and a large private insurer to identify adults aged 18-64 with an ED visit for renal colic (N = 65,346). Episodes were defined using statistically significant deviations in weekly healthcare charges. Multivariable binary and ordered logistic regression assessed associations between patient characteristics, pharmacotherapy, provider follow-up, and three outcomes: definitive surgery, 30-day ED revisit, and total episode charges.

Among patients undergoing surgery, episode duration averaged 10 weeks for privately insured and 6 weeks for Medicaid patients. Among nonsurgical patients, episode duration averaged 4 weeks for both groups. Earlier post-ED ambulatory urology follow-up reduced odds of 30-day revisit (private: OR 0.37, P < .0001; Medicaid: OR 0.29, P < .0001). Alpha blocker prescription at the time of ED discharge was associated with lower 30-day revisit risk (private: OR 0.80, P < .0001; Medicaid: OR 0.83, P < .001). 30-day ED revisit was associated with higher episode-specific expenditures, regardless of surgical/insurance status.

We employed a novel claims-based approach to renal colic episode definition, which revealed nuances in care utilization and access driven by potentially modifiable factors like insurance status and timing of post-ED ambulatory follow-up.