Evaluating a rapid fit-testing method for N95 respirators in Chinese healthcare workers: a paired crossover...

China lacks standardized rapid fit-testing protocols for N95 respirators. This exploratory study assessed the feasibility between the OSHA 2.5-min quantitative fit-testing protocol and the 6-min Chinese reference protocol among Chinese healthcare workers, also assessing mask seal degradation during chest compressions.

A total of 54 nurses and physicians were recruited for this paired crossover simulation and diagnostic agreement study. Participants underwent quantitative fit testing using two N95 respirator models: D918 (a foldable respirator) and D920 (a cup-type respirator). Fit-test outcomes obtained using the 2.5-min protocol were compared with those obtained using the 6-min reference protocol. Paired pass results were analyzed using McNemar's test, and agreement was assessed using Cohen's kappa with 95% confidence intervals. Diagnostic indices, including sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratios, were calculated from raw 2 × 2 contingency tables. Seal integrity during simulated chest compressions was also evaluated.

Using the 6-min protocol as the reference, the D918 respirator showed pass rates of 75.93% [95%CI, 0.63 to 0.85] for the 2.5-min protocol and 81.48% [95%CI, 0.69 to 0.90] for the 6-min protocol. The corresponding sensitivity, specificity, PPV, PLR, and NLR were 97.56% [95%CI, 0.85 to 1.00], 69.23% [95%CI, 0.39 to 0.90], and 90.9% [95%CI, 0.77 to 0.97], 3.17 [95%CI, 1.40 to 7.18] and 0.03 [95%CI, 0.00 to 0.26], respectively. For the D920 respirator, pass rates were 92.59% [95%CI, 0.82 to 0.97] and 94.44% [95%CI, 0.85 to 0.99] for the 2.5-min and 6-min protocols, respectively, with sensitivity, specificity, PPV, PLR and NLR of 100% [95%CI, 0.91 to 1.00], 75% [95%CI, 0.22 to 0.99], 94.4% [95%CI, 0.84 to 0.99], 4.00 [95%CI, 0.73 to 21.84] and 0.02 [95%CI, 0 to not estimable]. During CC, baseline seal integrity was achieved in 98.15% of participants. The D918 showed clinically significant leakage during (44.44%) and post-compression (29.63%), contrasting with D920's maintained performance (p > 0.05). Multivariate analysis identified nasal width (OR 8.71 [95%CI, 2.74 to 31.8]) and auricular arc length (OR 0.78 [95%CI, 0.64 to 0.95]) as independent predictors of fit quality, demonstrating inverse and positive correlations with seal integrity, respectively.

In this exploratory paired simulation study, the OSHA 2.5-min protocol showed preliminary agreement with the 6-min Chinese reference protocol for quantitative N95 respirator fit testing among Chinese healthcare workers, particularly for the D920 respirator. However, the study does not establish formal equivalence or non-inferiority. Larger multicenter studies with prespecified non-inferiority margins are needed before the rapid protocol can be recommended as a replacement for the standard 6-min protocol.