What is the incidence of renal impairment in patients presenting with renal colic?

Abstract

Objective: Nonsteroidal anti-inflammatory drugs (NSAIDs) are the recommended agents for treatment of renal colic pain. Some clinicians express concern about their prescription when renal function in unknown. This study aimed to determine the prevalence of renal impairment in patients presenting to emergency departments (ED) with a clinical diagnosis of renal colic. Patients and methods: This retrospective observational study included patients with an ED diagnosis of renal colic. Exclusions were patients younger than 18, previous inclusion and missing medical records. The primary outcome of interest was the proportion of patients with abnormal estimated glomerular filtration rate (eGFR), stratified by eGFR group. Results: A total of 1805 patients were studied: median age 46 years and 72% male. In the population overall, the proportion with eGFR less than 45 was 2.6% (95% confidence interval (CI) 2–3.4%). In the subgroup without known renal impairment, the proportion with eGFR less than 45 was 1.7% (95% CI 1.2–2.4%). On multivariate analysis, the only variable predictive of eGFR less than 45 in patients without known renal impairment was age 60 years or older (odds ratio 1.09, 95% CI 1.06–1.12). Conclusion: The proportion of patients with clinical renal colic who have an eGFR less than 45 at ED presentation is very low (<2%). This evidence supports administration of NSAIDs for pain relief in patients without known renal impairment before eGFR is known. Level of evidence: Not applicable for this multicentre audit.