Table 2. IRRs for Deviation in Start of Spring and Asthma Hospitalization in Maryland During 2001 to 2012.
| Covariate | IRR (95% CI) | ||
|---|---|---|---|
| Model 1a | Model 2b | Model 3c | |
| Phenology | |||
| Normal | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Very early | 1.17 (1.07-1.28) | 1.10 (1.02-1.20) | 1.10 (1.01-1.20) |
| Early | 0.96 (0.89-1.03) | 0.95 (0.88-1.03) | 0.95 (0.88-1.04) |
| Late | 1.07 (1.00-1.15) | 1.03 (0.97-1.11) | 1.03 (0.97-1.11) |
| Extreme heat event | NA | 1.00 (0.99-1.01) | 1.00 (0.99-1.01) |
| PM2.5 concentration | NA | 0.94 (0.87-1.03) | 0.94 (0.87-1.02) |
| Poverty | NA | NA | 1.05 (1.02-1.08) |
Abbreviations: IRR, incidence rate ratio; NA, not applicable; PM2.5, particulate matter with an aerodynamic diameter less than 2.5 μm.
a
Model 1 was unadjusted.
b
Model 2 was adjusted for extreme heat event and PM2.5 concentration.
c
Model 3 was additionally adjusted for poverty.