Baseline characteristics of Veterans Health Administration rheumatoid arthritis cohort
| Characteristic | Patients with RA (N=37 568) |
|---|---|
| Demographics and RA-related variables | |
| Age (years), mean (SD) | 62.9 (12.1) |
| Male, % | 90 |
| Caucasian, % | 71 |
| Serology available, % | 75 |
| Seropositive, %* | 69 |
| Seronegative, %* | 31 |
| Erythrocyte sedimentation rate (mm/h), mean (SD)† | 29.8 (26.2) |
| C reactive protein (mg/dL), mean (SD)† | 1.8 (2.9) |
| Socioeconomic status (SES) Index Score, median (IQR)‡ | 50.7 (48.3–53.2) |
| Tobacco use, % | |
| Current | 27.7 |
| Former | 41.0 |
| Lifetime non-smoker | 18.5 |
| Missing tobacco use | 12.8 |
| Medications | |
| Prednisone or other oral steroids, % | 66 |
| Statins, % | 30 |
| Biologics§, % | 21 |
| DMARD including methotrexate, % | 50 |
| Non-biological DMARD other than methotrexate, % | 29 |
| Comorbidities | |
| Hypertension, % | 33 |
| Heart failure, % | 3 |
| Diabetes, % | 12 |
| Chronic obstructive pulmonary disease, % | 9 |
| Chronic kidney disease, % | 1 |
| Body mass index, median (IQR) | 27.6 (24.4–31.2) |
| Lipid levels | |
| Total cholesterol (mg/dL), mean (SD)¶ | 181.2 (35.5) |
| HDL-C (mg/dL), mean (SD)¶ | 45.1 (12.9) |
| LDL-C (mg/dL), mean (SD)¶ | 108.2 (29.8) |
*Serological status was determined throughout the 12-month baseline period and throughout the entire follow-up. The remaining 25% of patients were classified as having missing serological status.
†Distribution of ESR and CRP was determined using the most recent laboratory value prior the index date; there were 46% non-missing values for ESR and 34% for CRP in the baseline period. Additional lab data were modelled in a time-varying way after the start of follow-up.
‡SES Index Score based on the Agency for Healthcare Research and Quality SES indicators report from 2008.23 The range of this scale goes from 0 to 100 where higher scores represent higher SES status. Median distribution of SES index score for the US population is 50.5.
§Biological included all antitumor necrosis factor biologics, rituximab and abatacept as either monotherapy or combined with non-biological DMARD.
¶Distribution of total cholesterol, HDL-C and LDL-C was determined using the most recent laboratory value prior index date; there were 72% non-missing values for total cholesterol, 70% for HDL-C and 68% for LDL-C in the baseline period. Additional lab data were modelled in a time-varying way after the start of follow-up.
DMARD, disease-modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; PO, oral; RA, rheumatoid arthritis.