Table 5

Assessment for bias using modified National Heart, Lung and Blood Institute (NHRBI) study quality assessment tools

StudiesCriteria
12345678910
Liau et al48·······
Gross and Horstman49·······
Oestenstad et al50·········
Oestenstad and Perkins27·········
Brazile et al51········
Han52········
Han and Choi29········
Kim et al53··········
Zhuang et al54······
Oestenstad et al55··········
McMahon et al56···N/A···
Zhuang et al57·········
Winter et al58···N/A····
Wilkinson et al59··N/A···
Oestenstad and Bartolucci 60·········
Spies et al61·······
Ciotti et al30··N/A·····
Earle-Richardson et al62··N/A···
Yu et al63········
Bergman et a64········
Kim et al65·········
Lin and Chen66········
Manganyi et al28]········
Honarbakhsh et al67········
Huh et al68··········
Foereland et al69···N/A·····
Winski et al70·······
Fakherpour et al71··········
Zhang et al72·········
De‐Yñigo‐Mojado et al73·········
Fakherpouret al74····N/A····
Williams et al75····N/A····
  • ●Criteria met; ◐ criteria partially met; ◯ criteria not met.

  • Criteria: (1) were aims and objectives clearly stated? (2) was the study population clearly specified and defined? (3) were inclusion and exclusion criteria for being in the study prespecified and applied uniformly to all participants? (4) was a sample size justification, power description, variance or effect estimates provided? (5) were methods of anthropometric measurement clearly described, valid, reliable and implemented consistently across all study participants? (6) were other independent variables clearly defined, valid, reliable and implemented consistently across all study participants? (7) were the dependent variables clearly defined, valid, reliable and implemented consistently across all study participants? (8) is it clear what was used for analysis or to determine statistical significance estimates? (9) results—were basic data adequately described? (10) were limitations of study discussed?

  • Where indicated as ‘criteria not met’ for criteria, (3) inclusion and/or exclusion criteria have not been specified. Where indicated as ‘criteria not met’ for criteria, (4) no sample size justification or power calculation has been reported, nor assessment of variance or effect size. Most studies did not report sample size justification or power calculation, but criteria were deemed to be satisfied if variance or effect estimate provided.

  • Anthropometric measurements made from photographs of participants using established landmarks for five of seven facial dimensions. Protection factor scores required to pass not reported. Correlation analysis performed for only a white male subset of the study population.48

  • Correlation analysis for facial dimensions and respiratory protective equipment (RPE) fit reported as having been performed but results were not provided as no significant correlations made.49

  • The study was underpowered to assess for race.50

  • Facial measurements not entirely in keeping with standard anthropometric landmarks and measurements, as judged by included figure.51

  • Physical examination and pulmonary function performed but inclusion/exclusion criteria not stated.29 52

  • Study population not specified. Some participants did not test all respirator models and were substituted by others with similar face size categories.54

  • Once a successful fit test was obtained other models were not tested. The order of masks tested was applied consistently.56

  • Results of effect of gender, age and occupation reported only briefly.57

  • Data on facial categories collected rather than anthropometric measurements. Respirator for testing was selected by the tester based on observed facial characteristics rather than measured facial dimensions and Los Alamos National Laboratory categories. Once a successful fit test was obtained other models were not tested. Healthcare workers who failed fit testing were not tracked and if returned for second fit-testing sessions were treated as independent events.59

  • Two facial measurements were collected only on a small proportion of participants. SD provided but no between group comparisons available. Correlation analysis was not performed between the facial dimensions and fit factor.61

  • Once a successful fit test was obtained other models were not tested.62

  • Estimate of variance and/or effect size were irrelevant for aims of study to determine if RPE fit of respirator size relates to respirator fit test panel facial size categories.64

  • Participants that were not clean shaven were initially included in the analysis which likely skews results given known effect of facial hair on RPE performance.28

  • Factors such as facial hair presence was not records, and could influence the difference in fit factors between genders.73

  • Anthropometric data not collected. Ambiguous categorisation on ethnicity of participants as South East Asian and non-Asian.75