Table 3.
The diagnostic value of morning stiffness (duration and severity) in early arthritis for classifying RA
| OR (95% CI) adjusted for age and gender | OR (95% CI) adjusted for age, gender, SJC, ACPA, RF ESR and symptom duration | Sensitivity | Specificity | PPV | NPV | |
|---|---|---|---|---|---|---|
| Leiden EAC | ||||||
| ≥30 minutes | 3.37 (2.83-4.03) | 2.22 (1.66-2.96) | 77.0% | 51.5% | 53.5% | 75.5% |
| ≥60 minutes | 2.92 (2.47-3.44) | 1.72 (1.31-2.25) | 61.2% | 66.1% | 56.7% | 70.1% |
| ≥90 minutes | 2.44 (2.04-2.92) | 1.61 (1.19-2.18) | 39.1% | 80.3% | 59.0% | 64.5% |
| VAS 34-67 mm | 1.87 (1.48-2.36) | 2.10 (1.43-3.09) | 56.5% | 60.0% | 49.1% | 66.8% |
| VAS ≥68 mm | 2.38 (1.89-3.00) | 1.93 (1.32-2.83) | 60.7% | 61.8% | 55.3% | 66.8% |
| ESPOIR | ||||||
| ≥30 minutes | 2.64 (1.81-3.87) | 1.76 (1.07-2.88) | 74.2% | 47.8% | 87.6% | 27.1% |
| ≥60 minutes | 2.33 (1.59-3.44) | 1.68 (1.03-2.74) | 55.4% | 64.7% | 88.7% | 22.6% |
| ≥90 minutes | 2.02 (1.28-3.20) | 1.64 (0.92-2.92) | 32.5% | 80.9% | 89.4% | 19.4% |
| VAS 34-67 mm | 2.04 (1.32-3.17) | 1.93 (1.10-3.37) | 61.0% | 56.3% | 85.7% | 25.1% |
| VAS 68–100 mm | 2.46 (1.53-3.96) | 1.65 (0.88-3.11) | 57.3% | 63.7% | 87.6% | 25.1% |
RA is classified according to the 2010 ACR-EULAR criteria. VAS: (0 to 100 mm). In the analyses of VAS morning stiffness three categories were formed, the reference group was a VAS 0 to 33 mm. The sensitivity, specificity, PPV and NPV of the VAS morning stiffness were calculated against this reference group. RA, rheumatoid arthritis; OR, odds ratio; CI, confidence interval; SJC, swollen joint count; ACPA, anti-citrullinated protein antibody; RF, rheumatoid factor; ESR, erythrocyte sedimentation rate; PPV, positive predictive value; NPV, negative predictive value; EAC, Early Arthritis Clinic; VAS, visual analogue scale; ESPOIR, Evaluation et Suivi de POlyarthrites Indifférenciées Récentes; ACR, American College of Rheumatology; EULAR, European League Against Rheumatism.