Maxime Verhoeven

170 Chapter 9 ABSTRACT Objective To determine the ability of the HandScan (assessing inflammation in hand and wrist joints using optical spectral transmission, OST) to longitudinally measure RA disease activity compared to DAS28, and to determine whether short-term (i.e., 1 month) OST- score changes can predict treatment response at 3 or 6 months. Methods Participants visited the out-patient-clinic before start of (additional) RA-medication and 1, 3 and 6 months thereafter. Disease activity was monitored at each visit with the HandScan and DAS28 in parallel. A mixed effects model with DAS28 as outcome variable with a random intercept at patient level, visit month and DAS28 one visit earlier was used to evaluate whether OST-score changes are related to changes in DAS28. Binary logistic regression was used to test the predictive value of short-term OST- score changes together with baseline OST-score for achievement of treatment response (EULAR or ACR criteria). All models were adjusted for RA stage (early or established). Results In total 64 RA patients were included. One unit OST-score change was found to be related to an average DAS28 change of 0.03 (95%CI 0.01–0.06), p=0.03. When adding OST-score as variable in the longitudinal model, the model’s ability to estimate DAS28 (i.e., explained variance) increased with 2%, to 59%. Neither baseline OST-score, nor short-term OST- score change was predictive for treatment response at 3 or at 6 months. Conclusion A longitudinal association of OST-score with DAS28 exists, although explained variance is low. The predictive ability of short-term changes in HandScan for treatment response is limited.