Table 4

Summary of studies that have examined the impact of methicillin resistance on mortality in Staphylococcus aureus bacteremiaa

StudyNo. of MRSA isolates/no. of MSSA isolatesMortality rate for MRSA vs MSSA (%)Mortality risk for MRSA vs MSSAAdjustment(s) for confoundersReference
Meta-analyses
    Meta-analysis of 9 studies (1990–2000); mortality778/1,43129 vs 12Pooled RR, 2.03 (95% CI, 1.55–2.65; P < 0.001)None 317
    Meta-analysis of 31 studies (1980–2000); mortality1,360/2,603Not statedPooled OR, 1.93 (95% CI, 1.54–2.42; P < 0.03)Varied between studies analyzed 42
Studies that found MRSA to be an independent predictor of mortality (multivariate analysis)
    Single-center retrospective Taiwanese study (1990–2004); 30-day mortality851/29749.8 vs 27.6OR, 1.78 (95% CI, 1.3–2.44; P < 0.001)None 308
    Single-center retrospective Belgian study (1992–1998); 30-day mortality47/3863 vs 18HR, 1.93 (95% CI, 1.18–3.18; P < 0.01)None 18
    Multicenter retrospective U.S. study (1995–2003); 90-day infection-related mortality184/23534.2 vs 19.6HR, 1.8 (95% CI, 1.2–3.0; P < 0.01)Patients with pneumonia 266
    Single-center retrospective (2002–2004) and prospective (2005-2007) German study; 90-day all-cause mortality67/45442 vs 19OR, 2.6 (95% CI, 1.4–4.9; P < 0.01)None 237
    Single-center retrospective Belgian study (2002–2004); infection-related in-hospital mortality66/8852 vs 32OR, 3.04 (95% CI, 1.15–8.04; P = 0.021)None 168
    Multicenter prospective Asian study (2004–2006); 30-day mortality329/38033.1 vs 17.1OR, 1.69 (95% CI, 1.15–2.49; P < 0.01)None 133
    Single-center retrospective United Kingdom study (2005–2006); 90-day mortality34/2635.3 vs 19.2Time-averaged HR of 1.69 (95% CI, 0.72–4)Age, gender, comorbidities, hospitalization (first admission, time averaged) 321
Studies that found MRSA not to be an independent predictor of mortality (upon multivariate analysis)
    Single-center retrospective U.S. study (1991–2000); infection-related mortality170/18330.6 vs 15.3OR, 1.4 (95% CI, 0.7–3; P = 0.4)Age, site of infection, APACHE score, ICU at onset, hospital onset, and delayed therapy 175
    Single-center retrospective Canadian study (1991–2005); 30-day mortality69/74633 vs 23OR, 2.21 (95% CI, 0.99–4.96; P value ND)Age, gender, comorbidities, residence, absence of treatment, site of infection 5
    Single-center prospective United Kingdom study (1995–2000); infection-related mortality382/43329.6 vs 13.6OR, 1.72 (95% CI, 0.92–3.2; P = 0.09)Age, hospital specialty, primary site of infection 195
    Single-center retrospective French study (1997–1998); infection-related mortality30/6943.3 vs 20.3OR, 2.8 (95% CI, 0.99–7.1; P value ND)Appropriate treatment within the first 72 h 286
    Single-center prospective U.S. study (1997–2000); in-hospital mortality96/25222.9 vs 19.8OR, 0.72 (95% CI, 0.39–1.96; P = 0.45)None 41
    Multicenter retrospective United Kingdom study (1997–2004); 30-day mortality227/21434.0 vs 27.0OR, 1.49 (95% CI, 0.99–2.26; P value ND)None 322
    Single-center retrospective Brazilian study (2000–2001); infection-related mortality61/5054.9 vs 24.7HR, 3.52 (95% CI, 0.96–6.60; P = 0.06)Adequacy of therapy, gender, age, severity of clinical status and underlying illness 89
    Single-center prospective Taiwanese study (2001–2006); 30-day all-cause mortality30/18510.0 vs 13.2OR, 0.74 (95% CI, 0.22–2.45; P value ND)None 310
    Multicenter prospective Asian study (2004–2006); 30-day mortality2007/170116.2 vs 10.8Not statedAge, comorbidities, source of infection, health care onset 134
    Single-center retrospective U.S. study (2004–2008); patients ≥80 yr of age; in-hospital mortality46/3034.8 vs 20.0OR, 2.1 (95% CI, 0.7–6.3; P = 0.16)None 15
    Multicenter prospective Australian study (2007–2008); 30-day all-cause mortality450/1,41530.0 vs 17.7OR, 1.04 (95% CI, 0.58–1.86; P = 0.89)None 296
  • a Only studies post-2000 and not included in the meta-analyses by Cosgrove et al. (42) and Whitby et al. (317) are represented.

  • MRSA, methicillin-resistant S. aureus; MSSA, methicillin-sensitive S. aureus; OR, odds ratio; CI, confidence interval; P, probability; ND, not described.