Table 4.
Adjusted long-term associations between air pollutants and COVID-19-related hospitalization in single and two-pollutant models, comparing all-cause with cause-specific hospitalizations
| All cause (n = 47,174) | COVID-19 or respiratory* (n = 36,505) | COVID-19* (n = 33,981) | ||
|---|---|---|---|---|
| Exposure | HR (95% CI) | HR (95% CI) | HR (95% CI) | |
| COVAIR-CAT models | ||||
| NO2 (increase: 16.1) | Single-pollutant | 1.25 (1.22–1.29) | 1.27 (1.23–1.32) | 1.27 (1.23–1.32) |
| PM2.5 (increase: 3.2) | Single-pollutant | 1.19 (1.16–1.21) | 1.21 (1.18–1.24) | 1.21 (1.18–1.24) |
| COVAIR-CAT models | ||||
| NO2 (increase: 16.1) | Adjusted for PM2.5 | 1.12 (1.08–1.17) | 1.13 (1.08–1.19) | 1.12 (1.07–1.18) |
| NO2 (increase: 16.1) | Adjusted for O3 | 1.24 (1.19–1.29) | 1.29 (1.23–1.35) | 1.26 (1.20–1.32) |
| PM2.5 (increase: 3.2) | Adjusted for NO2 | 1.12 (1.08–1.15) | 1.13 (1.09–1.17) | 1.14 (1.10–1.18) |
| PM2.5 (increase: 3.2) | Adjusted for O3 | 1.16 (1.13–1.19) | 1.19 (1.16–1.22) | 1.18 (1.15–1.22) |
Model adjusted as Model 4: age (continuous term, penalized spline with 6 df) + sex (strata, 2 categories) + smoking status (factor, 3 categories) + individual income (factor, 3 categories) + health risk group (factor, 4 categories) + small area socioeconomic index (continuous term) + percentage of non-Spanish nationals (continuous term) + distance to the closest primary care unit (continuous term) + urbanicity (strata, 3 categories) + average weekly of test-positive proportion (continuous term) + health region (strata, 7 categories).
*Defined by the ICD-10 code first position.