Chronic heart failure and mortality in patients with community-acquired Staphylococcus aureus bacteremia: a population-based cohort study

BACKGROUND Patients with chronic heart failure (CHF) may experience higher mortality of Staphylococcus aureus bacteremia (SAB) than patients without CHF due to insufficient cardiovascular responses during systemic infection. We investigated 90-day mortality in SAB patients with and without CHF. METHODS Using population-based medical databases, we conducted a cohort study of all adult patients with community-acquired SAB (CA-SAB) in Northern Denmark, 2000-2011. Ninety-day mortality after SAB for patients with and without CHF was estimated by the Kaplan-Meier method. Based on Cox regression analysis, we computed hazard ratios as estimates of mortality rate ratios (MRRs) overall and stratified by CHF-related conditions (e.g., cardiomyopathy and valvular heart disease), CHF severity (defined by daily dosage of loop-diuretics), and CHF duration while adjusting for potential confounders. RESULTS Among 2638 SAB patients, 390 (14.8 %) had a history of CHF. Ninety-day mortality was 45 % in patients with CHF and 30 % in patients without CHF, which yielded an adjusted MRR (aMRR) of 1.24 (95 % CI, 1.04-1.48). Compared to patients without CHF, the excess risk of death was most pronounced among patients with valvular heart disease (aMRR = 1.73 (95 % CI, 1.26-2.38)), patients with daily loop-diuretic dosages of 81-159 mg/day (aMRR = 1.55 (95 % CI, 1.11-2.14)) and ≥160 mg/day (aMRR = 1.62 (95 % CI, 1.21-2.18)), and among patients with <3 years of CHF duration (aMRR = 1.43 (95 % CI, 1.14-1.78)). CONCLUSION CA-SAB patients with CHF experienced increased 90-day mortality compared to patients without CHF.