Fifty-three RCTs were identified (17,420 participants, range 21 to 1,897). The mean quality score was 2.7 (median 2, range 1 to 5); 26 trials had a high quality score and there were 21 double-blind trials.
Effectiveness (treatment success or cure): Overall there was no significant difference in effectiveness between comparator antibiotics and vancomycin (OR 1.08, 95% CI 0.98 to 1.18; Ι²=0%; 41 comparisons) with no significant differences between vancomycin and individual antibiotics. Comparators were as effective as vancomycin for the ITT population and the microbiologically evaluable population but significantly more effective versus vancomycin for the clinically evaluable population (OR 1.14, 95% CI 1.02 to 1.27; Ι²=12%; 49 comparisons); this result was also significant for single-blind and open-label studies but not for double-blind studies. There were no significant differences in effectiveness overall for febrile neutropenia, pneumonia or skin and soft-tissue infections but linezolid was significantly more effective than vancomycin for skin and soft-tissue infections (OR 1.61, 95% CI 1.07 to 2.43).
Mortality: There was no significant difference in mortality for comparators versus vancomycin (OR 1.09, 95% CI 0.96 to 1.23; Ι²=0%; 41 comparisons) and no significant differences between vancomycin and individual antibiotics. There was no significant difference for the overall ITT population. Mortality was higher for the comparator antibiotics in single-blind and open-label studies but not for double-blind studies. This significant result was dominated by one open-label study of patients with both gram-negative and gram-positive infections that compared linezolid with vancomycin; the result was no longer significant when it was omitted from the meta-analysis.
Adverse events: There were overall no significant differences in adverse events (OR 1.07, 95% CI 0.90 to 1.28), withdrawals or episodes of recurrent infections for comparators versus vancomycin and no significant differences for the subgroup analyses for double-blind and for single-blind and open-label studies. Results for individual antibiotic comparisons with vancomycin varied in significance.