Table 2. Association of outdoor air pollutants with pterygium: multivariate logistic regression (n = 23,276).
| Variables | Model 1 Multivariate OR (95% CI, P value) |
Model 2 Multivariate OR (95% CI, P value) |
|---|---|---|
| Air pollution factors (average during 2 years) | ||
| Humidity, % (5% increase) | 1.15 (1.02–1.29, 0.436) | 1.08 (0.89–1.30, 0.444) |
| PM10, µg/m3 (5 µg/m3 increase) | 0.99 (0.87–1.11, 0.553) | 0.97 (0.85–1.11, 0.621) |
| O3, ppm (0.003 ppm increase) | 1.08 (0.91–1.28, 0.443) | 1.06 (0.89–1.27, 0.511) |
| NO2, ppm (0.003 ppm increase) | 0.93 (0.86–0.99, 0.231) | 0.96 (0.89–1.03, 0.219) |
| SO2, ppm (0.003 ppm increase) | 0.89 (0.64–1.29, 0.438) | 0.83 (0.58–1.20, 0.324) |
| Sociodemographic factors | ||
| Age (10-year increase)* | 1.90 (1.82–1.99, < 0.001) | 1.86 (1.77–1.94, < 0.001) |
| Sex (men/women)* | 1.32 (1.17–1.50, < 0.001) | 1.31 (1.15–1.51, < 0.001) |
| Region of residence (urban/rural) | 0.84 (0.59–1.20, 0.333) | 0.88 (0.62–1.26, 0.494) |
| Education level (university or higher/high school or less)* | 0.33 (0.25–0.44, < 0.001) | 0.38 (0.29–0.51, < 0.001) |
| Income level (high/low) | 0.99 (0.85–1.14, 0.826) | 1.01 (0.88–1.17, 0.876) |
| Other factors | ||
| Sun exposure (more/less than 5 hours a day)* | NA | 1.31 (1.12–1.54, 0.001) |
| Myopia (+/−)* | NA | 0.68 (0.58–0.80, < 0.001) |
Model 1: sociodemographic factors were modeled as covariates; Model 2: sociodemographic factors, sun exposure, and myopia were modeled as covariates.
OR = odds ratio, CI = confidence interval, PM10 = particulate matter with aerodynamic diameter less than 10 µm, O3 = ozone, NO2 = nitrogen dioxide, SO2 = sulfur dioxide, NA = not available.
*Associated with pterygium in multivariate logistic regression.