Background characteristics of the study groups at baseline
| ERA (N=53) | CRA (N=28) | Controls (N=43) | p Value | |
|---|---|---|---|---|
| Women, N (%) | 45 (85) | 23 (82) | 38 (88) | 0.758 |
| Age (years), mean±SD | 51±15 | 52±11 | 56±13 | 0.160 |
| Number of teeth, median (IQR) | 27 (23–28) | 27 (22–28) | 27 (25–28) | 0.628 |
| Rheumatoid factor present (%) | 42 (79.2) | 18 (69.2) | 3 (8.1)* | <0.001 |
| Disease duration (months), mean±SD | 10.4±17.1 | 176±116.8 | <0.001† | |
| ESR (mm/hour), median (IQR) | 20 (11–34) | 20 (9–46) | 2 (2–10)* | <0.001 |
| CRP (mg/L), median (IQR) | 6 (3–14) | 18 (5–30) | 2 (2–3)* | <0.001 |
| DAS28, median (IQR) | 4.0 (3.2–4.8) | 4.1(3.0–4.9) | 0.974 | |
| Education, N (%)‡ | ||||
| Lower | 20 (37.7) | 9 (36.0) | 16 (61) | 0.174 |
| Secondary | 27 (50.9) | 12 (48.0) | 6 (23.1) | |
| Higher | 6 (11.3) | 4 (16.0) | 4 (15.4) | |
| Smoking, N (%) | ||||
| Never | 35 (66.0) | 23 (82.1) | 36 (83.7) | |
| Former | 7 (13.0) | 2 (7.0) | 1 (2.0) | |
| Current | 11 (21.0) | 3 (11.0) | 6 (14.0) | 0.197 |
| Alcohol use, N (%) | ||||
| Seldom/none | 28 (52.8) | 12 (42.9) | 13 (30.2) | |
| Monthly/weekly | 25 (47.2) | 16 (57.1) | 30 (69.8) | 0.084 |
*N=37, missing data from six control participants, no visit to laboratory.
†p value obtained by non-parametric Kruskal-Wallis test comparing patients with ERA and CRA.
‡Missing data: 3 patients with CRA and 17 control participants for unknown reasons.
p Values by cross-tabulating with χ2 across the study groups.
CRA, chronic rheumatoid arthritis; CRP, serum C reactive protein level; DAS28, Disease Activity Score (28-joint count); ERA, early rheumatoid arthritis; ESR, erythrocyte sedimentation rate; N, number of patients.