Methods: We searched the peer reviewed and grey literature between January, 1990 and December, 2014. For clinical studies we included English-language randomized controlled trials (RCTs), cohort studies and case-control studies that included data on N95 respirators or equivalent and surgical masks used to prevent transmissible ARIs. The primary outcome for the meta-analysis was laboratory-confirmed respiratory infection. Secondary outcomes for the meta-analysis included influenza-like illness (ILI) and workplace absenteeism. Surrogate exposure studies were examined and summarized, but not included in meta-analyses. Outcomes related to surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage.
Results: Six studies were included in our meta-analysis. There was no significant difference in associated risk of laboratory-confirmed respiratory infection when N95 respirators and surgical masks were compared in RCTs (Odds Ratio [OR] 0.89, 95% confidence interval [CI] 0.64 to 1.24), the cohort study (OR 0.43, CI 0.03 to 6.41), or case-control studies (OR 0.91, CI 0.25 to 3.36). Similarly, there was no significant difference in associated risk of ILI when N95 respirators and surgical masks were compared in RCTs (OR 0.51, CI 0.19 to 1.41) or for reported workplace absenteeism in RCTs (OR 0.92, CI 0.57 to 1.50). Twenty-three additional surrogate exposure studies were included. These studies in general demonstrated that N95 respirators have less filter penetration, face-seal leakage, and total inward leakage than surgical masks.
Conclusion: Although N95 respirators compared to surgical masks may have a protective advantage in laboratory evaluations, our meta-analysis identified that data from clinical settings does not provide evidence that N95 respirators offer superior protection for health care workers against transmissible ARIs in a clinical setting.
J. Johnstone, None
R. Copes, None
B. Schwartz, None
G. Garber, None