Table 3.
Hazard ratios for the incidence of COPD for an interquartile change in each pollutant
| Adjustment factors | PM10 (n=807 401) | PM2.5 (n=807 401) | SO2 (n=800 360) | NO2 (n=807 000) | O3 (n=801 380) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| HR | 95% CI | HR | 95% CI | HR | 95% CI | HR | 95% CI | HR | 95% CI | |
| Outcome=First diagnosis of COPD on GP record in 2003–2007, Exclusions=Any COPD recorded on GP record prior to 2003 | ||||||||||
| Age and sex | 1.10 | 1.02 to 1.19 | 1.12 | 1.04 to 1.21 | 1.14 | 1.09 to 1.19 | 1.17 | 1.08 to 1.26 | 0.88 | 0.82 to 0.94 |
| +Smoking and BMI | 1.06 | 0.99 to 1.13 | 1.07 | 1.00 to 1.15 | 1.11 | 1.07 to 1.16 | 1.11 | 1.03 to 1.20 | 0.91 | 0.85 to 0.97 |
| +IMD | 0.99 | 0.93 to 1.05 | 1.00 | 0.94 to 1.06 | 1.07 | 1.03 to 1.11 | 1.03 | 0.96 to 1.11 | 0.94 | 0.89 to 1.00 |
| Full model (10 unit increase) | 0.97 | 0.79 to 1.18 | 0.97 | 0.71 to 1.34 | 1.36 | 1.14 to 1.62 | 1.03 | 0.96 to 1.10 | 0.82 | 0.67 to 0.99 |
| Outcome=First diagnosis of COPD on GP record in 2003–2007, Exclusions=Any Markers of Respiratory Disease prior to 2003* | ||||||||||
| +IMD | 1.01 | 0.94 to 1.09 | 1.02 | 0.94 to 1.09 | 1.08 | 1.03 to 1.13 | 1.04 | 0.96 to 1.13 | 0.94 | 0.87 to 1.00 |
| Outcome=First Hospital Admission for COPD in 2003–2007, Exclusions=Any COPD recorded on GP record prior to 2003 | ||||||||||
| Age and sex | 1.21 | 1.11 to 1.32 | 1.23 | 1.13 to 1.34 | 1.11 | 1.05 to 1.17 | 1.25 | 1.14 to 1.36 | 0.87 | 0.80 to 0.95 |
| +Smoking and BMI | 1.15 | 1.06 to 1.24 | 1.16 | 1.08 to 1.26 | 1.08 | 1.02 to 1.13 | 1.17 | 1.08 to 1.28 | 0.90 | 0.84 to 0.97 |
| +IMD | 1.05 | 0.98 to 1.12 | 1.05 | 0.98 to 1.13 | 1.01 | 0.97 to 1.07 | 1.06 | 0.98 to 1.15 | 0.96 | 0.90 to 1.02 |
| Full model (10 unit increase) | 1.17 | 0.93 to 1.46 | 1.31 | 0.92 to 1.86 | 1.07 | 0.86 to 1.33 | 1.06 | 0.98 to 1.14 | 0.87 | 0.69 to 1.08 |
| Outcome=First Hospital Admission for COPD in 2003–2007 with additional GP diagnosis, Exclusions=Any COPD recorded on GP record prior to 2003 | ||||||||||
| +IMD | 1.05 | 0.96 to 1.14 | 1.05 | 0.97 to 1.14 | 1.04 | 0.98 to 1.10 | 1.04 | 0.94 to 1.15 | 0.97 | 0.90 to 1.05 |
Hazard ratios are for IQR change in pollutant level unless stated (PM10=3.0 µg/m3, PM2.5=1.9 µg/m3, SO2=2.2 µg/m3, NO2=10.7 µg/m3, O3=3.0 µg/m3). Practice is accounted for in the above models by the sandwich estimator to produce robust standard errors. *The numbers of patients in the analyses with this additional exclusion were: PM10/PM2.5 n=690 102, SO2 n=684 261, NO2 n=689 767, O3 n=684 261.
BMI, body mass index; COPD, chronic obstructive pulmonary disease; GP, general practitioner; HES, hospital episode statistics; IMD, Index of Multiple Deprivation.