Characteristics of RA patients with different numbers of erosive joints at first presentation (A) and the test characteristics and predictive values for developing rapid radiological progression during the first year of the disease (B).
| (A) Exact Number of Erosive Joints | ||||||||
|---|---|---|---|---|---|---|---|---|
| No. Patients, (%) | Women, N (%) | Age, yrs, Mean ± SD | Smoker, N (%) | ACPA+, N (%) | Symptom Duration, wks, Mean ± SD | CRP, mg/l, Mean ± SD | RRP* N (%) | |
| None | 137 (19.5) | 108 (78.8) | 45.4 (13.6) | 32 (25.8) | 61 (48.0) | 24.1 (23.1) | 20 (30) | 27 (26.2) |
| 1 | 99 (14.1) | 72 (72.7) | 50.6 (15.7) | 33 (34.7) | 45 (47.4) | 25.6 (19.5) | 22 (22) | 19 (22.9) |
| 2 | 78 (11.1) | 52 (66.7) | 53.1 (14.4) | 25 (33.8) | 44 (57.1) | 27.3 (21.3) | 31 (30) | 23 (33.8) |
| 3 | 77 (11.0) | 51 (66.2) | 56.1 (15.2) | 19 (26.0) | 48 (64.0) | 28.3 (25.3) | 22 (26) | 26 (40.0) |
| 4 | 69 (9.8) | 45 (65.2) | 57.7 (14.7) | 17 (27.0) | 39 (59.1) | 25.6 (21.2) | 33 (33) | 24 (44.4) |
| 5 | 38 (5.4) | 23 (60.5) | 62.9 (12.9) | 10 (28.6) | 19 (51.4) | 18.6 (11.8) | 35 (40) | 14 (45.2) |
| ≥ 6 | 189 (27.0) | 116 (61.4) | 67.4 (11.4) | 42 (24.0) | 92 (49.2) | 27.8 (22.6) | 37 (40) | 78 (53.4) |
| Total | 687 | |||||||
| (B) Number of Erosive Joints Used as Cutoff | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| No. Patients, N (%) | RRP, N (%) | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | LR+ (95% CI) | LR− (95% CI) | AUC (SEM) | |
| None | 103 (18.7) | 27 (26.2) | |||||||
| ≥ 1 | 447 (81.3) | 184 (41.1) | 0.87 (0.82–0.91) | 0.22 (0.18–0.27) | 0.41 (0.37–0.46) | 0.74 (0.64–0.82) | 1.12 (1.04–1.21) | 0.57 (0.39–0.83) | 0.55 (0.025) |
| ≥ 2 | 364 (66.2) | 165 (45.3) | 0.78 (0.72–0.83) | 0.41 (0.36–0.47) | 0.45 (0.4–0.51) | 0.75 (0.68–0.81) | 1.33 (1.19–1.49) | 0.52 (0.41–0.69) | 0.60 (0.024) |
| ≥ 3 | 296 (53.8) | 142 (48.0) | 0.67 (0.6–0.73) | 0.55 (0.49–0.6) | 0.48 (0.42–0.54) | 0.73 (0.67–0.78) | 1.48 (1.28–1.72) | 0.60 (0.49–0.73) | 0.61 (0.025) |
| ≥ 4 | 231 (42) | 116 (50.2) | 0.55 (0.48–0.62) | 0.66 (0.61–0.71) | 0.50 (0.44–0.57) | 0.70 (0.65–0.75) | 1.62 (1.34–1.96) | 0.68 (0.59–0.79) | 0.61 (0.025) |
| ≥ 5 | 177 (32.2) | 92 (52.0) | 0.44 (0.37–0.5) | 0.75 (0.7–0.79) | 0.52 (0.44–0.59) | 0.68 (0.63–0.72) | 1.73 (1.37–2.21) | 0.75 (0.66–0.85) | 0.59 (0.025) |
| ≥ 6 | 146 (26.5) | 78 (53.4) | 0.37 (0.34–0.42) | 0.80 (0.75–0.83) | 0.53 (0.45–0.62) | 0.67 (0.62–0.72) | 1.84 (1.4–2.43) | 0.79 (0.71–0.88) | 0.59 (0.025) |
| Total | 550 | 211 (38.4) | |||||||
↵* Not all patients had a radiograph 1 year post-followup. In 550 patients, the presence of rapid radiological progression (RRP) could be calculated. ACPA: anticitrullinated protein antibodies; CRP: C-reactive protein; PPV: positive predictive value; NPV: negative predictive value; LR: likelihood ratio; AUC: area under the curve; RA: rheumatoid arthritis.