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A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers.
Influenza Other Respir Viruses. 2011 May; 5(3):170-9.IO

Abstract

BACKGROUND

We compared the efficacy of medical masks, N95 respirators (fit tested and non fit tested), in health care workers (HCWs).

METHODS

A cluster randomized clinical trial (RCT) of 1441 HCWs in 15 Beijing hospitals was performed during the 2008/2009 winter. Participants wore masks or respirators during the entire work shift for 4 weeks. Outcomes included clinical respiratory illness (CRI), influenza-like illness (ILI), laboratory-confirmed respiratory virus infection and influenza. A convenience no-mask/respirator group of 481 health workers from nine hospitals was compared.

FINDINGS

The rates of CRI (3·9% versus 6·7%), ILI (0·3% versus 0·6%), laboratory-confirmed respiratory virus (1·4% versus 2·6%) and influenza (0·3% versus 1%) infection were consistently lower for the N95 group compared to medical masks. By intention-to-treat analysis, when P values were adjusted for clustering, non-fit-tested N95 respirators were significantly more protective than medical masks against CRI, but no other outcomes were significant. The rates of all outcomes were higher in the convenience no-mask group compared to the intervention arms. There was no significant difference in outcomes between the N95 arms with and without fit testing. Rates of fit test failure were low. In a post hoc analysis adjusted for potential confounders, N95 masks and hospital level were significant, but medical masks, vaccination, handwashing and high-risk procedures were not.

INTERPRETATION

Rates of infection in the medical mask group were double that in the N95 group. A benefit of respirators is suggested but would need to be confirmed by a larger trial, as this study may have been underpowered. The finding on fit testing is specific to the type of respirator used in the study and cannot be generalized to other respirators.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN: ACTRN12609000257268 (http://www.anzctr.org.au).

Authors+Show Affiliations

School of Public Health and Community Medicine, Faculty of Medicine, University of New South Wales, Sydney, Australia. r.macintyre@unsw.edu.auNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21477136

Citation

MacIntyre, Chandini Raina, et al. "A Cluster Randomized Clinical Trial Comparing Fit-tested and Non-fit-tested N95 Respirators to Medical Masks to Prevent Respiratory Virus Infection in Health Care Workers." Influenza and Other Respiratory Viruses, vol. 5, no. 3, 2011, pp. 170-9.
MacIntyre CR, Wang Q, Cauchemez S, et al. A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers. Influenza Other Respir Viruses. 2011;5(3):170-9.
MacIntyre, C. R., Wang, Q., Cauchemez, S., Seale, H., Dwyer, D. E., Yang, P., Shi, W., Gao, Z., Pang, X., Zhang, Y., Wang, X., Duan, W., Rahman, B., & Ferguson, N. (2011). A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers. Influenza and Other Respiratory Viruses, 5(3), 170-9. https://doi.org/10.1111/j.1750-2659.2011.00198.x
MacIntyre CR, et al. A Cluster Randomized Clinical Trial Comparing Fit-tested and Non-fit-tested N95 Respirators to Medical Masks to Prevent Respiratory Virus Infection in Health Care Workers. Influenza Other Respir Viruses. 2011;5(3):170-9. PubMed PMID: 21477136.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers. AU - MacIntyre,Chandini Raina, AU - Wang,Quanyi, AU - Cauchemez,Simon, AU - Seale,Holly, AU - Dwyer,Dominic E, AU - Yang,Peng, AU - Shi,Weixian, AU - Gao,Zhanhai, AU - Pang,Xinghuo, AU - Zhang,Yi, AU - Wang,Xiaoli, AU - Duan,Wei, AU - Rahman,Bayzidur, AU - Ferguson,Neil, Y1 - 2011/01/27/ PY - 2011/4/12/entrez PY - 2011/4/12/pubmed PY - 2011/7/23/medline SP - 170 EP - 9 JF - Influenza and other respiratory viruses JO - Influenza Other Respir Viruses VL - 5 IS - 3 N2 - BACKGROUND: We compared the efficacy of medical masks, N95 respirators (fit tested and non fit tested), in health care workers (HCWs). METHODS: A cluster randomized clinical trial (RCT) of 1441 HCWs in 15 Beijing hospitals was performed during the 2008/2009 winter. Participants wore masks or respirators during the entire work shift for 4 weeks. Outcomes included clinical respiratory illness (CRI), influenza-like illness (ILI), laboratory-confirmed respiratory virus infection and influenza. A convenience no-mask/respirator group of 481 health workers from nine hospitals was compared. FINDINGS: The rates of CRI (3·9% versus 6·7%), ILI (0·3% versus 0·6%), laboratory-confirmed respiratory virus (1·4% versus 2·6%) and influenza (0·3% versus 1%) infection were consistently lower for the N95 group compared to medical masks. By intention-to-treat analysis, when P values were adjusted for clustering, non-fit-tested N95 respirators were significantly more protective than medical masks against CRI, but no other outcomes were significant. The rates of all outcomes were higher in the convenience no-mask group compared to the intervention arms. There was no significant difference in outcomes between the N95 arms with and without fit testing. Rates of fit test failure were low. In a post hoc analysis adjusted for potential confounders, N95 masks and hospital level were significant, but medical masks, vaccination, handwashing and high-risk procedures were not. INTERPRETATION: Rates of infection in the medical mask group were double that in the N95 group. A benefit of respirators is suggested but would need to be confirmed by a larger trial, as this study may have been underpowered. The finding on fit testing is specific to the type of respirator used in the study and cannot be generalized to other respirators. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN: ACTRN12609000257268 (http://www.anzctr.org.au). SN - 1750-2659 UR - https://www.unboundmedicine.com/medline/citation/21477136/A_cluster_randomized_clinical_trial_comparing_fit_tested_and_non_fit_tested_N95_respirators_to_medical_masks_to_prevent_respiratory_virus_infection_in_health_care_workers_ L2 - https://doi.org/10.1111/j.1750-2659.2011.00198.x DB - PRIME DP - Unbound Medicine ER -