Table 3.
Multivariable Analyses on Factors Associated With the Detection of Influenza Viral RNA in Air
| Risk Factor | Best Fit Model | Competing Model 1 | Competing Model 2 | Competing Model 3 |
|---|---|---|---|---|
| aOR (95% CI); P Value | aOR (95% CI); P Value | aOR (95% CI); P Value | aOR (95% CI); P Value | |
| Crowdedness (No. of occupants on site)a | ||||
| Low | Reference | Reference | Reference | Reference |
| Intermediate | 1.21 (.73–2.04); P = .461 | 1.22 (.73–2.05); P = .452 | 1.18 (.70–2.00); P = .530 | 1.16 (.69–1.95); P = .585 |
| High | 2.29 (1.44–3.71); P < .001 | 2.33 (1.46–3.79); P < .001 | 2.19 (1.36–3.60); P = .002 | 2.13 (1.33–3.49); P = .002 |
| Indoor temperature (°C) | ||||
| Numeric | 1.14 (1.05–1.23); P = .001 | 1.19 (1.07–1.33); P = .001 | 1.12 (1.02–1.23); P = .014 | 1.13 (1.04–1.23); P = .003 |
| Indoor AH (kg/m3) | ||||
| Numeric (per 0.002 increase) | … | 0.89 (.74–1.07); P = .213 | … | … |
| Outdoor AH (kg/m3) | ||||
| Numeric (per 0.002 increase) | … | … | 1.03 (.95–1.12); P = .475 | … |
| AH difference (indoor–outdoor) (kg/m3) | ||||
| Numeric (per 0.002 increase) | … | … | … | 0.94 (.86–1.03); P = .181 |
Sampling performed on teaching days vs holidays was highly associated with numbers of occupants on site (χ2 test, P < .001); as such, crowdedness (number of occupants on site) was included in the multivariable analysis.
Abbreviations: AH, absolute humidity; aOR, adjusted odds ratio; CI, confidence interval.
aNumber of occupants was categorized into high, intermediate, and low based on the numeric data distribution: high (upper 33%), intermediate (middle 33%), and low (lower 33%)