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.