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

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Please cite this paper as: MacIntyre et al. (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 DOI: 10.1111/j.1750‐2659.2010.00198.x.

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).

Related collections

Most cited references 27

Record: found
Abstract: found
Article: not found

Epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in Hong Kong

Christl Donnelly, Azra C. Ghani, Gabriel Leung … (2003)

Summary Background Health authorities worldwide, especially in the Asia Pacific region, are seeking effective public-health interventions in the continuing epidemic of severe acute respiratory syndrome (SARS). We assessed the epidemiology of SARS in Hong Kong. Methods We included 1425 cases reported up to April 28, 2003. An integrated database was constructed from several sources containing information on epidemiological, demographic, and clinical variables. We estimated the key epidemiological distributions: infection to onset, onset to admission, admission to death, and admission to discharge. We measured associations between the estimated case fatality rate and patients’age and the time from onset to admission. Findings After the initial phase of exponential growth, the rate of confirmed cases fell to less than 20 per day by April 28. Public-health interventions included encouragement to report to hospital rapidly after the onset of clinical symptoms, contact tracing for confirmed and suspected cases, and quarantining, monitoring, and restricting the travel of contacts. The mean incubation period of the disease is estimated to be 6.4 days (95% Cl 5.2–7.7). The mean time from onset of clinical symptoms to admission to hospital varied between 3 and 5 days, with longer times earlier in the epidemic. The estimated case fatality rate was 13.2% (9.8–16.8) for patients younger than 60 years and 43.3% (35.2–52.4) for patients aged 60 years or older assuming a parametric γ distribution. A non-parametric method yielded estimates of 6.8% (4.0–9.6) and 55.0% (45.3–64.7), respectively. Case clusters have played an important part in the course of the epidemic. Interpretation Patients’age was strongly associated with outcome. The time between onset of symptoms and admission to hospital did not alter outcome, but shorter intervals will be important to the wider population by restricting the infectious period before patients are placed in quarantine. Published online May 7, 2003 http://image.thelancet.com/extras/03art4453web.pdf

0 comments Cited 423 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial.

Benjamin Cowling, Kwok-Hung Chan, Vicky J. Fang … (2009)

Few data are available about the effectiveness of nonpharmaceutical interventions for preventing influenza virus transmission. To investigate whether hand hygiene and use of facemasks prevents household transmission of influenza. Cluster randomized, controlled trial. Randomization was computer generated; allocation was concealed from treating physicians and clinics and implemented by study nurses at the time of the initial household visit. Participants and personnel administering the interventions were not blinded to group assignment. (ClinicalTrials.gov registration number: NCT00425893) Households in Hong Kong. 407 people presenting to outpatient clinics with influenza-like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households. Lifestyle education (control) (134 households), hand hygiene (136 households), or surgical facemasks plus hand hygiene (137 households) for all household members. Influenza virus infection in contacts, as confirmed by reverse-transcription polymerase chain reaction (RT-PCR) or diagnosed clinically after 7 days. Sixty (8%) contacts in the 259 households had RT-PCR-confirmed influenza virus infection in the 7 days after intervention. Hand hygiene with or without facemasks seemed to reduce influenza transmission, but the differences compared with the control group were not significant. In 154 households in which interventions were implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR-confirmed infection seemed reduced, an effect attributable to fewer infections among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87]). Adherence to interventions varied. The delay from index patient symptom onset to intervention and variable adherence may have mitigated intervention effectiveness. Hand hygiene and facemasks seemed to prevent household transmission of influenza virus when implemented within 36 hours of index patient symptom onset. These findings suggest that nonpharmaceutical interventions are important for mitigation of pandemic and interpandemic influenza. Centers for Disease Control and Prevention.

0 comments Cited 208 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Surgical mask vs N95 respirator for preventing influenza among health care workers: a randomized trial.

Mark Loeb, Nancy Dafoe, James Mahony … (2009)

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. To compare the surgical mask with the N95 respirator in protecting health care workers against influenza. Noninferiority randomized controlled trial of 446 nurses in emergency departments, medical units, and pediatric units in 8 tertiary care Ontario hospitals. 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. 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%. 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%. 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. clinicaltrials.gov Identifier: NCT00756574

0 comments Cited 196 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Journal

Journal ID (nlm-ta): Influenza Other Respir Viruses

Journal ID (iso-abbrev): Influenza Other Respir Viruses

Journal ID (doi): 10.1111/(ISSN)1750-2659

Journal ID (publisher-id): IRV

Title: Influenza and Other Respiratory Viruses

Publisher: Blackwell Publishing Ltd (Oxford, UK )

ISSN (Print): 1750-2640

ISSN (Electronic): 1750-2659

Publication date (Electronic): 27 January 2011

Publication date (Print): May 2011

Volume: 5

Issue: 3 ( doiID: 10.1111/irv.2011.5.issue-3 )

Pages: 170-179

Affiliations

[ ¹ ]School of Public Health and Community Medicine, Faculty of Medicine, University of New South Wales, Sydney, Australia

[ ² ]The Beijing Center for Disease Prevention and Control, Beijing, China

[ ³ ]MRC Center for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK

[ ⁴ ]Institute for Clinical Pathology and Medical Research, Westmead Hospital, Sydney, Australia.

Author notes

[*]Professor C. Raina MacIntyre, Professor of Infectious Diseases Epidemiology and Head of School, School of Public Health and Community Medicine, Faculty of Medicine, University of New South Wales, Samuels Building, Room 325, Sydney, 2052 NSW, Australia. E‐mail: r.macintyre@ 123456unsw.edu.au