| Characteristic | Total | Odds Ratio (95% CI) | p-Value | |
| Age | Per year increase | 8423 | 0.99 (0.98 - 0.99) | <0.0001 |
| Histology | Squamous (reference) | 1721 | . | |
| Adenocarcinoma | 5930 | 4.78 (4.13 - 5.52) | <0.0001 | |
| Other | 523 | 1.58 (1.23 - 2.02) | ||
| Adenosquamous | 178 | 3.84 (2.73 - 5.41) | ||
| Bronchioloalveolar carcinoma | 71 | 4.53 (2.73 - 7.50) | ||
| Practice Region | South (reference) | 5288 | . | 0.0009 |
| West | 1767 | 0.98 (0.87 - 1.11) | ||
| Midwest | 880 | 1.36 (1.16 - 1.60) | ||
| Northeast | 488 | 0.92 (0.74 - 1.14) | ||
| Practice Size | Small (reference) | 2327 | . | 0.035 |
| Medium | 4465 | 1.11 (0.98 - 1.25) | ||
| Large | 1631 | 1.28 (1.06 - 1.54) |