Prevalence and Significance of Renal Dysfunction Among Emergency Department Observation Patients With Chest Pain

OBJECTIVES: Previous studies have demonstrated increased risk of acute coronary syndrome among patients with chest pain and renal dysfunction. The objective of this study was to investigate the impact of renal dysfunction on cardiac outcomes in patients with chest pain in an emergency department observation unit (EDOU). METHODS: We conducted a 5-year prospective evaluation of patients evaluated in the EDOU for chest pain. We collected baseline information and data from the emergency department visit, EDOU stay, inpatient admission, and the 30-day period after presentation to the emergency department. We calculated glomerular filtration rate (GFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. We stratified patients as having mild (GFR 60-89 mL/min per 1.73 m) or at least moderate (GFR <60) renal dysfunction. We evaluated the rate of major adverse cardiac events (MACE: myocardial infarction, stent, coronary artery bypass graft, and death). RESULTS: Of 1067 enrolled EDOU patients, the majority had at least mild renal dysfunction: 39% [95% confidence interval (95% CI): 36.1%-42%] had a GFR between 60 and 89, and 16% (95% CI: 14%-18.4%) had a GFR <60. MACE rates increased with decreasing GFR: 3.3% (95% CI: 2.1%-5.3%) for GFR ≥90, 7.3% (95% CI: 5.2%-10.2%) for GFR 60-89, and 9.1% (95% CI: 5.7%-14.3%) for GFR <60 (P = 0.005). In multivariate analysis, patients with at least mild renal dysfunction (GFR < 90) were at greater risk of MACE (P = 0.028). CONCLUSIONS: We noted a high prevalence of renal dysfunction among EDOU patients evaluated for chest pain. Even those with mild renal dysfunction demonstrated an increased risk of MACE. Clinicians may wish to consider renal dysfunction in selecting appropriate patients for EDOU placement.