Renal infarction Incidence, Risk Factors and Risk of Mortality and Kidney Replacement Therapy: A Retrospective Cohort Study.

Abstract

Background: Renal infarction is a rare medical condition, with most studies focusing on prevalence and risk factors. Very few studies examined long term outcomes, and to our knowledge there are no studies comparing patients with renal infarction to a control group for long term outcomes such as mortality or kidney replacement therapy (KRT). We used a hospital population database to examine incidence, prevalence and risk factors for renal infarction and long-term outcomes such as mortality and KRT, comparing patients with renal infarction to the general population and to a matched cohort.

Methods: Retrospective cohort study of adult patients from an Australian Local Health (2008- 2017). We examined the incidence and prevalence of renal infarction along with risk factors associated with a renal infarction. We compared patients with a renal infarction to the general population and a 1:5 matched cohort to examine risk of mortality and KRT. Logistic regression was used to examine risk factors for renal infraction with odds ratio (OR) and 95% confidence intervals (95%CI), and Cox proportional hazard regression was used to determine hazard ratio (HR).

Results: Of the 140,099 patients included a renal infarction occurred in 119 (0.1%) with a crude incidence of 1.9 per 10,000 patient years (95%CI 1.6- 2.2). Factors associated with the risk of a renal infarction were age (OR 1.17 by decade, 95%CI 1.06- 1.30), atrial fibrillation (OR 2.55, 95%CI 1.54- 4.28), valvular heart disease (OR 2.88, 95%CI 1.26- 6.57) and peripheral vascular disease (OR 7.69, 95%CI 4.54- 13.4). During follow-up there was no increased risk of mortality after adjusting for age and comorbidities (HR 1.19, 95%CI 0.89- 1.61). However, the risk of KRT was significantly elevated even after adjusted for confounder (HR 8.4, 95%CI 3.6- 19.7). These results remained valid in the matched analysis.

Conclusions: Renal infarction is an uncommon event. The risk of mortality is not significantly increased when compared to the general population after adjusting for confounders. However, the risk of KRT remains significantly increased.