一项关于外科口罩和N95口罩对医护人员流感防护力的随机比较试验(二者无明显差别)

David

Vol. 302 No. 17, November 4, 2009  
JAMA-EXPRESS
Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers
A Randomized Trial
一项关于外科口罩和N95口罩对医护人员流感防护力的随机比较试验
Mark Loeb, MD, MSc; Nancy Dafoe, RN; James Mahony, PhD; Michael John, MD; Alicia Sarabia, MD; Verne Glavin, MD; Richard Webby, PhD; Marek Smieja, MD; David J. D. Earn, PhD; Sylvia Chong, BSc; Ashley Webb, BS; Stephen D. Walter, PhD


JAMA. 2009;302(17):1865-1871. Published online October 1, 2009 (doi:10.1001/jama.2009.1466).

ABSTRACT   

Context  Data about the effectiveness of the surgical mask compared with the N95 respirator for protecting health care workers against influenza are sparse. Given the likelihood that N95 respirators will be in short supply during a pandemic and not available in many countries, knowing the effectiveness of the surgical mask is of public health importance.

Objective  To compare the surgical mask with the N95 respirator in protecting health care workers against influenza.

Design, Setting, and Participants  Noninferiority randomized controlled trial of 446 nurses in emergency departments, medical units, and pediatric units in 8 tertiary care Ontario hospitals.

Intervention  Assignment to either a fit-tested N95 respirator or a surgical mask when providing care to patients with febrile respiratory illness during the 2008-2009 influenza season.

Main Outcome Measures  The primary outcome was laboratory-confirmed influenza measured by polymerase chain reaction or a 4-fold rise in hemagglutinin titers. Effectiveness of the surgical mask was assessed as noninferiority of the surgical mask compared with the N95 respirator. The criterion for noninferiority was met if the lower limit of the 95% confidence interval (CI) for the reduction in incidence (N95 respirator minus surgical group) was greater than –9%.

Results  Between September 23, 2008, and December 8, 2008, 478 nurses were assessed for eligibility and 446 nurses were enrolled and randomly assigned the intervention; 225 were allocated to receive surgical masks and 221 to N95 respirators. Influenza infection occurred in 50 nurses (23.6%) in the surgical mask group and in 48 (22.9%) in the N95 respirator group (absolute risk difference, –0.73%; 95% CI, –8.8% to 7.3%; P = .86), the lower confidence limit being inside the noninferiority limit of –9%.

Conclusion Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza.
(在Ontario医院的护士中，与N95口罩相比，使用外科口罩对流感病毒的防护力无明显差别。)
Trial Registration  clinicaltrials.gov Identifier: NCT00756574