Maxime Verhoeven

207 DAS28 vs. DAS-OST; rheumatologist’s clinical classification RESULTS Patients Data of 1505 unique RA patients was used. Patients’ demographic and clinical data are shown in Table 1. Mean DAS28 and DAS-OST were both 2.5. Mean OST-score was somewhat higher in males than in females. According to clinical classification, RA of 79% of the patients was classified as inactive; 7 patients could not be clinically classified. Table 1 Patients’ demographics and clinical data. All Female Male Patients’ demographics Number of patients, n (%) 1505 (100) 979 (65) 526 (35) Age (years), mean (SD) 65.5 (12.1) 64.1 (12.7) 68.0 (10.6) Duration of RA (years), mean (SD) 11.5 (8.3) 11.8 (8.3) 11.0 (8.5) Seropositivity, n (%) 1068 (71) 691 (71) 377 (72) Clinical data DAS28, mean (SD) 2.5 (1.3) 2.6 (1.2) 2.3 (1.3) ESR (mm in 1 st hour), median (IQR) 9.0 (5.0 – 21.0) 9.0 (5.0 – 21.0) 8.0 (2.0 – 19.0) SJC28, median (IQR) 0 (0 – 2) 0 (0 – 2) 0 (0 – 2) TJC28, median (IQR) 0 (0 – 1) 0 (0 – 2) 0 (0 – 1) VAS global, median (IQR) 25.0 (10.0 – 50.0) 30.0 (10.0 – 50.0) 20.0 (10.0 – 43.0) DAS-OST, mean (SD) 2.5 (1.2) 2.6 (1.2) 2.3 (1.2) OST-score, mean (SD) 12.7 (5.3) 11.3 (4.7) 15.2 (5.3) Clinical classification, n (%)  - Active  - Inactive  - Not interpretable 295 (20) 1203 (79) 7 (1) 195 (20) 781 (79) 3 (1) 100 (19) 422 (80) 4 (1) SD= standard deviation; Seropositivity= presence of rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies; IQR= interquartile range; DAS28= disease activity score assessing 28 joints; ESR= erythrocyte sedimentation rate; SJC28= swollen joint count assessing 28 joints; TJC28= tender joint count assessing 28 joints; VAS= patients’ visual analogue scale of general health, range 0-100=worst; DAS-OST= disease activity score using optical spectral transmission; OST= optical spectral transmission, range 0-66=worst. Agreement The relationship between DAS28 and DAS-OST is graphically shown in Supplementary Figure S1; the ICC was 0.88 (95%CI 0.87-0.89). The mean difference between DAS28 and DAS-OST is shown in Supplementary Figure S2. Discriminatory values AU-ROC to classify RA patients as active/inactive for DAS28 was 0.88 (95%CI 0.85- 0.90) and for DAS-OST and single OST-score, 0.78 (95%CI 0.75-0.81) and 0.59 (95%CI 11