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In Staphylococcus aureus bacteremia, mortality rates in randomized controlled trials (RCTs) are consistently lower than observational studies. Stringent eligibility criteria and omission of early deaths in RCTs contribute to this mortality gap. Clinicians should acknowledge the possibility of a lower treatment effect when applying RCT results to bedside care. [ABSTRACT FROM AUTHOR]

Background Deaths following Staphylococcus aureus bacteremia (SAB) may be related or unrelated to the infection. In SAB therapeutics research, the length of follow-up should be optimized to capture most attributable deaths and minimize nonattributable deaths. We performed a secondary analysis of a systematic review to describe attributable mortality in SAB over time. Methods We systematically searched Medline, Embase, and Cochrane Database of Systematic Reviews from 1 January 1991 to 7 May 2021 for human observational studies of SAB. To be included in this secondary analysis, the study must have reported attributable mortality. Two reviewers extracted study data and assessed risk of bias independently. Pooling of study estimates was not performed due to heterogeneity in the definition of attributable deaths. Results Twenty-four observational cohort studies were included. The median proportion of all-cause deaths that were attributable to SAB was 77% (interquartile range [IQR], 72%–89%) at 1 month and 62% (IQR, 58%–75%) at 3 months. At 1 year, this proportion was 57% in 1 study. In 2 studies that described the rate of increase in mortality over time, 2-week follow-up captured 68 of 79 (86%) and 48 of 57 (84%) attributable deaths that occurred by 3 months. By comparison, 1-month follow-up captured 54 of 57 (95%) and 56 of 60 (93%) attributable deaths that occurred by 3 months in 2 studies. Conclusions The proportion of deaths that are attributable to SAB decreases as follow-up lengthens. Follow-up duration between 1 and 3 months seems optimal if evaluating processes of care that impact SAB mortality. Clinical Trials Registration PROSPERO CRD42021253891. [ABSTRACT FROM AUTHOR]

• Styphylococcus aureus bacteremia (SAB) is common in low and middle-income countries (LMIC). • LMIC are poorly represented in SAB research. • In-hospital mortality for SAB is much higher in LMIC than in high-income countries. Staphylococcus aureus bacteremia (SAB) is a common infection worldwide. We compared SAB mortality in low- and middle-income countries (LMIC) versus high-income countries (HIC) in a meta-analysis. We searched MEDLINE, Embase, and Cochrane Database of Systematic Reviews from 1991-2021 and included observational, single-country studies on patients with positive blood cultures for S. aureus. The main outcome was the proportion of patients with SAB who died in the hospital. A generalized linear mixed random-effects model was used to pool estimates, and a meta-regression was used to adjust for study-level characteristics. A total of 332 studies involving 517,671 patients in 39 countries were included. No study was conducted in a low-income country. Only 33 (10%) studies were performed in middle-income countries (MIC), which described 6,216 patients. The pooled in-hospital mortality was 32.4% (95% confidence interval [CI] 27.2%-38.2%, T2 = 0.3063) in MIC and 22.3% (95% CI 20.1%-24.6%, T2 = 0.3257) in HIC. In a meta-regression model, MIC had higher in-hospital mortality (adjusted odds ratio 1.37, 95% CI 1.11-1.71; P = 0.0042) than HIC. In SAB studies, LMIC are poorly represented. In-hospital mortality was significantly higher in MIC than in HIC. Research should be conducted in LMIC to characterize differences in care processes driving the mortality gap. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]