Table 3. Association of outdoor air pollutants with primary pterygium: multivariate logistic regression (n = 22,216).
| 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) | 1.21 (0.93–1.57, 0.162) | 1.19 (0.91–1.56, 0.206) |
| PM10, µg/m3 (5 µg/m3 increase)* | 1.22 (1.02–1.45, 0.029) | 1.23 (1.03–1.47, 0.023) |
| O3, ppm (0.003 ppm increase) | 1.09 (0.86–1.37, 0.479) | 1.09 (0.87–1.38, 0.439) |
| NO2, ppm (0.003 ppm increase) | 0.93 (0.84–1.02, 0.115) | 0.94 (0.85–1.04, 0.198) |
| SO2, ppm (0.003 ppm increase) | 0.89 (0.59–1.19, 0.292) | 0.91 (0.61–1.20, 0.301) |
| Sociodemographic factors | ||
| Age (10-year increase)* | 1.80 (1.69–1.92, < 0.001) | 1.74 (1.62–1.86, < 0.001) |
| Sex (men/women)* | 1.56 (1.24–1.95, < 0.001) | 1.44 (1.13–1.82, 0.003) |
| Region of residence (urban/rural) | 1.16 (0.72–1.85, 0.548) | 1.21 (0.75–1.94, 0.434) |
| Education level (university or higher/high school or less)* | 0.29 (0.18–0.45, < 0.001) | 0.34 (0.21–0.54, < 0.001) |
| Income level (high/ low) | 0.98 (0.77–1.24, 0.837) | 1.01 (0.79–1.29, 0.964) |
| Other factors | ||
| Sun exposure (more/less than 5 hours a day)* | NA | 1.54 (1.20–1.96, 0.001) |
| Myopia (+/−)* | NA | 0.62 (0.48–0.81, < 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.