Staphylococcus aureus bacteraemia mortality: a systematic review and meta-analysis

Precise estimates of mortality in Staphylococcus aureus bacteraemia (SAB) are important to convey prognosis and guide the design of interventional studies. We performed a systematic review and meta-analysis to estimate all-cause mortality in SAB and explore mortality change over time. The MEDLINE and Embase databases, as well as the Cochrane Database of Systematic Reviews, were searched from January 1, 1991 to May 7, 2021. Human observational studies on patients with S. aureus bloodstream infection were included. The study analyzed data of patients with a positive blood culture for S. aureus. Two independent reviewers extracted study data and assessed risk of bias using the Newcastle–Ottawa Scale. A generalized, linear, mixed random effects model was used to pool estimates. A total of 341 studies were included, describing a total of 536,791 patients. From 2011 onward, the estimated mortality was 10.4% (95% CI, 9.0%–12.1%) at 7 days, 13.3% (95% CI, 11.1%–15.8%) at 2 weeks, 18.1% (95% CI, 16.3%–20.0%) at 1 month, 27.0% (95% CI, 21.5%–33.3%) at 3 months, and 30.2% (95% CI, 22.4%–39.3%) at 1 year. In a meta-regression model of 1-month mortality, methicillin-resistant S. aureus had a higher mortality rate (adjusted OR (aOR): 1.04; 95% CI, 1.02–1.06 per 10% increase in methicillin-resistant S. aureus proportion). Compared with prior to 2001, more recent time periods had a lower mortality rate (aOR: 0.88; 95% CI, 0.75–1.03 for 2001–2010; aOR: 0.82; 95% CI, 0.69–0.97 for 2011 onward). SAB mortality has decreased over the last 3 decades. However, more than one in four patients will die within 3 months, and continuous improvement in care remains necessary.