Predictors of renal infarction in patients presenting to the emergency department with flank pain: A retrospective observational study

Objectives
Flank pain is a common symptom in the emergency department and can be caused by a variety of diseases. Renal infarction (RI) is a very rare disease, and many RI patients complain of flank pain. However, there is no definitive predictor of RI when patients complain of flank pain. This study aimed to identify the clinical factors for predicting RI in patients with flank pain.

Methods
This retrospective single-center study was conducted on patients complaining of flank pain from January 2016 to March 2020 at a South Korean tertiary care hospital. Exclusion criteria included patients who did not undergo contrast-enhanced computed tomography, age < 18 years, and trauma. Demographic and laboratory data were obtained from medical records. Logistic regression analysis was conducted to identify predictors of RI occurrence.

Results
In all, 2,131 patients were enrolled, and 39 (1.8%) had RI. From a multivariable logistic regression analysis, an age ≥ 65 years (odds ratio [OR], 3.249; 95% confidence interval [CI], 1.366–7.725; p = 0.008), male sex (OR, 2.846; 95% CI, 1.190–6.808; p = 0.019), atrial fibrillation (OR, 10.386; 95% CI, 3.724–28.961; p < 0.001), current smoker (OR, 10.022; 95% CI, 4.565–22.001; p < 0.001), and no hematuria (OR, 0.267; 95% CI, 0.114–0.628; p = 0.002) were significantly associated with the occurrence of RI.

Conclusions
Five clinical factors, i.e., age ≥ 65 years, male sex, atrial fibrillation, current smoker, and no hematuria, were significantly associated with the occurrence of RI in patients with flank pain.