Table 4.
Stratified associations between fine particulate matter and smoking characteristics with lung cancer incidence in the Nurses’ Health Study, adjusted for age, time period, and geographic region only (minimally adjusted models) or additional covariates (fully adjusted models), with various classifications of smoking based on cumulative pack-years or average packs, stratified by smoking status during follow-up, 1994–2010.
| Minimally adjusteda | Fully adjustedb | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Stratum | Covariate | HR | 95% CI | HR | 95% CI | ||||
| Never smokers | PM2.5 (per 10 μg/m3) | 1.24 | 0.74 | – | 2.06 | 1.27 | 0.76 | – | 2.12 |
| Former smokers | PM2.5 (per 10 μg/m3) | 1.35 | 1.00 | – | 1.81 | 1.35 | 1.00 | – | 1.82 |
| Smoking pack-years | 1.08 | 1.04 | – | 1.13 | 1.09 | 1.04 | – | 1.13 | |
| Smoking duration (years) | 1.02 | 1.01 | – | 1.04 | 1.02 | 1.00 | – | 1.04 | |
| Smoking cessation (months) | 1.00 | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | |
| Pack-years*age | 1.00 | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | |
| PM2.5 (per 10 μg/m3) | 1.27 | 0.95 | – | 1.71 | 1.27 | 0.95 | – | 1.71 | |
| Smoking average packs | 1.85 | 1.25 | – | 2.74 | 1.92 | 1.29 | – | 2.85 | |
| Smoking duration (years) | 1.07 | 1.05 | – | 1.08 | 1.06 | 1.04 | – | 1.08 | |
| Smoking cessation (months) | 1.00 | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | |
| Current or recent former smokers | PM2.5 (per 10 μg/m3) | 0.92 | 0.74 | – | 1.15 | 0.94 | 0.75 | – | 1.17 |
| Smoking pack-years | 1.07 | 1.05 | – | 1.10 | 1.07 | 1.04 | – | 1.10 | |
| Smoking duration (years) | 1.03 | 1.02 | – | 1.05 | 1.03 | 1.02 | – | 1.05 | |
| Smoking cessation (months) | 1.00 | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | |
| Pack-years*age | 1.00 | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | |
| PM2.5 (per 10 μg/m3) | 0.90 | 0.73 | – | 1.12 | 0.92 | 0.74 | – | 1.14 | |
| Smoking average packs | 43.01 | 24.37 | – | 75.92 | 42.72 | 24.01 | – | 75.99 | |
| Smoking duration (years) | 1.09 | 1.08 | – | 1.11 | 1.09 | 1.07 | – | 1.11 | |
| Smoking cessation (months) | 1.00 | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | |
Stratified by time period and age in months (in absence of age interaction), and adjusted for geographic region; also adjusted for age in months (in presence of age interaction)
Stratified by time period and age in months (in absence of age interaction), and adjusted for geographic region, body mass index, alcohol consumption, physical activity, overall diet quality, census tract median house value, census tract median income, and secondhand smoke exposure at home, at work, and during childhood; also adjusted for age in months (in presence of age interaction)
AIC: Akaike information criterion; CI: confidence interval; HR: hazard ratio; PM2.5: particulate matter < 2.5 μm in aerodynamic diameter