Table 2.
Characteristics of the Study Population at Baseline (N=8,417)*, %
| Characteristic* | Anti-TNF-α** N=4,200 | Non-biologic comparison*** N=4,217 |
|---|---|---|
| Year at index**** | ||
| 1998–1999 | 5 | 9 |
| 2000–2001 | 12 | 17 |
| 2002–2003 | 21 | 21 |
| 2004–2005 | 30 | 25 |
| 2006–2007 | 32 | 27 |
| Sex | ||
| Female | 66 | 59 |
| Age at index, years | ||
| 0–39 | 19 | 25 |
| 40–49 | 22 | 20 |
| 50–59 | 28 | 23 |
| 60–69 | 17 | 17 |
| 70–90 | 13 | 15 |
| Race/ethnicity | ||
| African-American | 7 | 8 |
| Asian | 11 | 11 |
| Hispanic | 6 | 5 |
| Native American | 2 | 2 |
| White | 66 | 66 |
| Other | 8 | 10 |
| Steroid exposure during 12-month baseline | ||
| Yes | 56 | 51 |
| Smoking | ||
| Never | 79 | 82 |
| Former | 6 | 7 |
| Current | 14 | 11 |
| Charlson comorbidity index | ||
| 0 | 29 | 53 |
| 1 | 54 | 34 |
| 2+ | 18 | 13 |
| Chronic pulmonary disease | ||
| Yes | 12 | 13 |
| Methotrexate during the 12-month look-back | ||
| Yes | 53 | 34 |
| Chest imaging | ||
| X-ray | 35 | 27 |
| Computed tomography | 3 | 2 |
*
Restricted to patients with propensity scores that overlapped.
**
Each patient is shown in the table only once. The 1,206 patients contributing person-years to both the anti-TNF-α group and the non-biologic comparison group are shown with the anti-TNF-α group.
***
All variables except gender and race are significant at p<0.01 in logistic regression models that contain all variables in this table.
****
The start date of the first eligible treatment episode (biologic or comparison) served as the index date. Consistent with an incident user design, patients were required to have 12 months of enrollment without an eligible treatment episode (biologic or comparison) before their index date.