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Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis.
CMAJ. 2016 May 17; 188(8):567-574.CMAJ

Abstract

BACKGROUND

Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections.

METHODS

We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case-control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage.

RESULTS

We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case-control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64-1.24; cohort study: OR 0.43, 95% CI 0.03-6.41; case-control studies: OR 0.91, 95% CI 0.25-3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19-1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57-1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks.

INTERPRETATION

Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

Authors+Show Affiliations

Public Health Ontario (Smith, MacDougall, Johnstone, Copes, Schwartz, Garber); Department of Medicine (Johnstone), University of Toronto; Dalla Lana School of Public Health (Copes, Schwartz), University of Toronto, Toronto, Ont.; Department of Medicine (Garber), University of Ottawa, Ottawa, Ont.Public Health Ontario (Smith, MacDougall, Johnstone, Copes, Schwartz, Garber); Department of Medicine (Johnstone), University of Toronto; Dalla Lana School of Public Health (Copes, Schwartz), University of Toronto, Toronto, Ont.; Department of Medicine (Garber), University of Ottawa, Ottawa, Ont.Public Health Ontario (Smith, MacDougall, Johnstone, Copes, Schwartz, Garber); Department of Medicine (Johnstone), University of Toronto; Dalla Lana School of Public Health (Copes, Schwartz), University of Toronto, Toronto, Ont.; Department of Medicine (Garber), University of Ottawa, Ottawa, Ont.Public Health Ontario (Smith, MacDougall, Johnstone, Copes, Schwartz, Garber); Department of Medicine (Johnstone), University of Toronto; Dalla Lana School of Public Health (Copes, Schwartz), University of Toronto, Toronto, Ont.; Department of Medicine (Garber), University of Ottawa, Ottawa, Ont.Public Health Ontario (Smith, MacDougall, Johnstone, Copes, Schwartz, Garber); Department of Medicine (Johnstone), University of Toronto; Dalla Lana School of Public Health (Copes, Schwartz), University of Toronto, Toronto, Ont.; Department of Medicine (Garber), University of Ottawa, Ottawa, Ont.Public Health Ontario (Smith, MacDougall, Johnstone, Copes, Schwartz, Garber); Department of Medicine (Johnstone), University of Toronto; Dalla Lana School of Public Health (Copes, Schwartz), University of Toronto, Toronto, Ont.; Department of Medicine (Garber), University of Ottawa, Ottawa, Ont. gary.garber@oahpp.ca.

Pub Type(s)

Journal Article
Meta-Analysis
Review
Systematic Review

Language

eng

PubMed ID

26952529

Citation

Smith, Jeffrey D., et al. "Effectiveness of N95 Respirators Versus Surgical Masks in Protecting Health Care Workers From Acute Respiratory Infection: a Systematic Review and Meta-analysis." CMAJ : Canadian Medical Association Journal = Journal De l'Association Medicale Canadienne, vol. 188, no. 8, 2016, pp. 567-574.
Smith JD, MacDougall CC, Johnstone J, et al. Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis. CMAJ. 2016;188(8):567-574.
Smith, J. D., MacDougall, C. C., Johnstone, J., Copes, R. A., Schwartz, B., & Garber, G. E. (2016). Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis. CMAJ : Canadian Medical Association Journal = Journal De l'Association Medicale Canadienne, 188(8), 567-574. https://doi.org/10.1503/cmaj.150835
Smith JD, et al. Effectiveness of N95 Respirators Versus Surgical Masks in Protecting Health Care Workers From Acute Respiratory Infection: a Systematic Review and Meta-analysis. CMAJ. 2016 May 17;188(8):567-574. PubMed PMID: 26952529.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis. AU - Smith,Jeffrey D, AU - MacDougall,Colin C, AU - Johnstone,Jennie, AU - Copes,Ray A, AU - Schwartz,Brian, AU - Garber,Gary E, Y1 - 2016/03/07/ PY - 2015/12/02/accepted PY - 2016/3/9/entrez PY - 2016/3/10/pubmed PY - 2017/4/4/medline SP - 567 EP - 574 JF - CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne JO - CMAJ VL - 188 IS - 8 N2 - BACKGROUND: Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections. METHODS: We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case-control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage. RESULTS: We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case-control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64-1.24; cohort study: OR 0.43, 95% CI 0.03-6.41; case-control studies: OR 0.91, 95% CI 0.25-3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19-1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57-1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks. INTERPRETATION: Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings. SN - 1488-2329 UR - https://www.unboundmedicine.com/medline/citation/26952529/Effectiveness_of_N95_respirators_versus_surgical_masks_in_protecting_health_care_workers_from_acute_respiratory_infection:_a_systematic_review_and_meta_analysis_ L2 - http://www.cmaj.ca/cgi/pmidlookup?view=long&pmid=26952529 DB - PRIME DP - Unbound Medicine ER -