Table 1.
Baseline characteristics of cases and controls
| Variables | Patients with RA | Controls | P value |
| n=89 | n=80 | ||
| Epidemiological characteristics | |||
| Age (years), mean (SD) | 56.6 (10.9) | 56.4 (10.9) | 0.902 |
| Female sex, n (%) | 67 (75.3) | 67 (83.8) | 0.189 |
| Smoking status | 0.117 | ||
| Never smoked, n (%) | 42 (47.2) | 49 (61.3) | |
| Ex-smoker, n (%) | 22 (24.7) | 11 (13.8) | |
| Smoker, n (%) | 25 (28.1) | 20 (25.0) | |
| Clinical–laboratory characteristics | |||
| Time since onset of RA (months), median (IQR) | 98.0 (78.5–123.5) | – | – |
| Diagnostic delay (months), median (IQR) | 10.9 (5.4–25.6) | – | – |
| Rheumatoid factor>10 U/mL, n (%) | 73 (82.0) | 1 (1.3) | <0.001 |
| ACPA>20 U/mL, n (%) | 67 (75.3) | 0 (0.0) | <0.001 |
| CRP (mg/dL), median (IQR) | 2.9 (2.9–3.4) | ||
| Erythrocyte sedimentation rate (mm/hour), median (IQR) | 11 (6.2–14) | 11.5 (7.8–21.3) | 0.088 |
| Number of swollen joints (0–28), median (IQR) | 0 (0–1) | ND | ND |
| Number of painful joints (0–28), median (IQR) | 1 (0–2) | ND | ND |
| VAS patient global (1–100 mm), median (IQR) | 30 (20–50) | ND | ND |
| DAS28-CRP on the index date, mean (SD) | 2.83 (1.1) | ND | ND |
| Remission–low activity, n (%) | 63 (71.0) | ND | ND |
| Moderate–high activity, n (%) | 26 (29.0) | ND | ND |
| Mean DAS28-CRP during follow-up, mean (SD) | 3.11 (0.8) | ND | ND |
| Remission–low activity, n (%) | 56 (63.0) | ND | ND |
| Moderate–high activity, n (%) | 33 (37.0) | ND | ND |
| Mean HAQ during follow-up, median (IQR) | 0.750 (0.0–1.1) | ND | ND |
| Synthetic DMARDs, n (%) | 78 (87.6) | 0 (0.0) | <0.001 |
| Biological DMARDs, n (%) | 35 (39.3) | 0 (0.0) | <0.001 |
| Combined DMARDs, n (%) | 25 (28.1) | 0 (0.0) | <0.001 |
| Methotrexate, n (%) | 21 (84.0) | ||
| Leflunomide, n (%) | 3 (12.0) | ||
| Sulfasalazine, n (%) | 1 (4.0) | ||
ACPA, anticitrullinated protein antibody; CRP, C reactive protein; DAS28, 28-Joint Disease Activity Score; DMARD, disease-modifying antirheumatic drug; HAQ, Health Assessment Questionnaire; ND, no data; RA, rheumatoid arthritis; VAS, visual analogue scale.