A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent XXXX in @entity283 .

@entity1 @entity283 @entity683 @entity281 @entity1729 @entity1576
BACKGROUND: We compared the efficacy of medical masks, N95 respirators (fit tested and non fit tested), in @entity283 ( @entity283 ). METHODS: A cluster randomized clinical trial (RCT) of 1441 @entity283 in 15 Beijing hospitals was performed during the 2008/2009 winter. @entity1 wore masks or respirators during the entire work shift for 4 weeks. Outcomes included clinical @entity1576 (CRI), @entity683 ( @entity683 ), laboratory-confirmed @entity1729 and @entity683 . 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%), @entity683 (0  3% versus 0  6%), laboratory-confirmed respiratory virus (1  4% versus 2  6%) and @entity683 (0  3% versus 1%) @entity281 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 @entity281 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).
