Table 1. Baseline characteristics of the training and test set populations (case and control)1.
| RA cohort | Controls | |||
| Training set (n = 33) | Test set (n = 16) | Training set (n = 30) | Test set (n = 15) | |
| Age (Years)2 | 59 (39; 65) | 58 (55; 68) | 31 (23; 60) | 36 (29; 58) |
| Female3 | 23 (70%) | 13 (76%) | 11 (37%) | 10 (67%) |
| Duration of disease (Days) | 113 (74; 261) | 91 (54; 225) | nd | nd |
| ACPA positive | 16 (48%) | 9 (56%) | nd | nd |
| ACPA (Units) | 5.7 (3; 161) | 47 (2; 214) | nd | nd |
| RF4 positive | 11 (73%) | 6 (86%) | nd | nd |
| RF4 (Units) | 15 (11; 30) | 20 (18; 55) | nd | nd |
| DAS28 score | 5.5 (4.3; 6.2) | 4.5 (3.9; 5.5) | nd | nd |
| HAQ score | 1.1 (0.8; 1.9) | 1.1 (0.5; 1.6) | nd | nd |
| CRP abnormal | 19 (63%) | 11 (73%) | nd | nd |
| CRP (mg/l) | 20.5 (6. 0; 41.0) | 19 (8.3; 38.5) | nd | nd |
nd, not determined; ACPA, anti-citrullinated protein antibodies; RF, rheumatoid factor; DAS28, 28 joint count disease activity score; HAQ, health assessment questionnaire score; CRP, C-reactive protein.
Differences between training set and test set within both RA and control groups were not statistically significant (Mann-Whitney for continuous values and Chi Square for categorical values; p<0.05) with the exception for the proportion of female in the control group between the training and test sets (p<0.05).
Difference in the median age value between groups is statistically significant between RA and control groups of the training set (p = 0.0023) and between RA and control groups of the test set (p = 0.0059).
Difference in the gender distribution between groups is statistically significant between RA and control groups of the training set (p<0.01) but not between RA and control groups of the test set (p>0.05) (Chi Square test).
Data missing for 18 patients in the training set and 9 patients in test set, percentage refers to proportion of patients tested.