Assessment of the Psychometric Properties of the Mask Usability Scale: A Measure of the Perceived Usability of N95 Respirators Among Healthcare Students and Staff.

aimTo test the reliability and construct validity of the Mask Usability Scale in healthcare students and staff.

designA methodological study involving repeated measures.

methodsThe study included two batches of participants: (1) 283 university nursing students and (2) 1753 participants composed of students (61%) and clinical staff (39%). All participants underwent N95 respirator fit tests and user seal checks. They also responded to the Mask Usability Scale, which comprises 11 items evaluated using Likert scales. The internal consistency was assessed using Cronbach's alpha and item-total correlation test. Test-retest reliability was evaluated by the intraclass correlation coefficient (ICC). The factor structure was initially identified through exploratory factor analysis (EFA), laying the groundwork for the model. This approach was followed by confirmatory factor analysis (CFA) to ensure the model fits with the standardised solution.

resultsExcluding items 9, 10 and 11, the study showed satisfactory internal consistency, evidenced by a Cronbach's alpha of 0.842 for the eight-item scale from the combined samples. Factors, such as 'Heat', 'Breathability', 'Tightness' and 'Ease in talking' showed moderate to strong correlations. The test-retest reliability in the batch one sample was acceptable with ICCs ranging between 0.69 and 0.71 for different models. The EFA and fit indices supported a two-factor structure. The first factor 'Comfort and Usage' included 'Heat', 'Breathability', 'Tightness', 'Ease in talking' and 'Prolonged use', which were keys for the usability of N95 respirators. The second factor 'Suitability' encompassed 'Itchy', 'Easily displaced' and 'Ear soreness'. The variance explained by the first and second factors was 49% and 12%, respectively, with a strong inter-factor correlation. The CFA results were satisfactory with fit metrics (NFI = 0.967, IFI = 0.969, TLI = 0.952, CFI = 0.969, RMSEA = 0.078 with 90% CI [0.069, 0.086] and p < 0.001) and a chi-squared to df ratio of 13.58.

conclusionThe eight-item mask usability scale exhibited satisfactory internal consistency and construct validity in both healthcare student and staff samples. IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE: The primary concern in the purchase policy of N95 respirators for clinical use is to strike the right balance between usability and fit rate (passing % of fit testing). Our study solidified the concept of quantifying the usability of respirators. With that mask usability scale measurement, a provision of benchmark and reference for the design and selection of respirators would be possible. This validated scale has significant implications for senior management in clinical settings and respirator manufacturers regarding the N95 respirator purchase policy and design. IMPACT: The results indicated the psychometric properties of mask usability scale in measuring the usability of N95 respirators. This scale is particularly valuable for assessing the perceptions of healthcare students and staff of factors, namely, 'Heat', 'Breathability', 'Tightness', 'Ease in talking', 'Prolonged use', 'Itchy', 'Easily displaced' and 'Ear soreness' concerning the use of N95 respirators. REPORTING

methodWe adhered to EQUATOR guidelines following the STROBE statement. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution.

trial registrationISRCTN registry: ISRCTN40115047.