Table 1.
Characteristics of the study sample
| ERA group (n=50) | At-risk group (n=50) | Control group (n=50) | P value | |
| Age, years (mean (SD)) | 52.1 (13.2) | 51.4 (10.3) | 51.2 (11.0) | 0.923* |
| Gender, female (n (%)) | 39 (78) | 38 (76) | 38 (76) | 0.963† |
| IgM-RF positive (n (%)) | 37 (74) | 46 (92) | 0 (0) | –‡ |
| ACPA positive (n (%)) | 31 (62) | 24 (48) | 0 (0) | –‡ |
| DAS28 (mean (SD)) | 2.61 (1.17) | – | – | – |
| RAPID-3 (median (IQR)) | 3.09 (1.07–4.47) | – | – | – |
| Analgesic medication <24 hours (n (%)) | 12 (24) | 16 (32) | 9 (18) | 0.265† |
| Pharmacological treatment for RA | ||||
| Methotrexate (n (%)) | 44 (88) | – | – | – |
| Other (n (%)) | 4 (8) | – | – | – |
| No pharmacological treatment (n (%)) | 2 (4) | – | – | – |
| Prednisone (n (%)) | 39 (78) | – | – | – |
*One-way ANOVA, F=0.080.
†χ2 test, χ2=0.075.
‡A difference in IgM-RF or ACPA positivity was not tested between the groups, because seropositivity was an inclusion criterion for the at-risk group and an exclusion criterion for the control group, and a difference is thus obvious.
ACPA, anticitrullinated protein antibodies; ANOVA, analysis of variance; DAS, Disease Activity Score; ERA, early rheumatoid arthritis; IgM-RF, IgM rheumatoid factor; RA, rheumatoid arthritis; RAPID-3, routine assessment of patient index data 3.