Maxime Verhoeven

180 Chapter 9 changes in disease activity as bDMARDs are known to more rapidly suppress tissue vascularity. 16,17 We tested whether the relation between OST-scores and DAS28 (-based response) was different between early (i.e., csDMARD treated-) and established (i.e., bDMARD treated-) patients, but could not detect a significant effect. Of course, as the effect of RA stage and treatment modality are intertwined in our study, this may have muddled this effect. And, in the bDMARD treated group, patients could have started their next bDMARD, which could have diminished the potential change in joint vascularity (and thus the ability of the HandScan to detect it), as vascularity was already reduced by the previous bDMARD. It is known that in patients even with inadequate response to bDMARDs, progression of joint damage is inhibited, 18 and thus probably also joint vascularity. Lastly, given that the HandScan only measures hands and wrists joints, it might be mainly applicable for the subset of RA patients with involvement of the hand joints. This first study assessing the longitudinal association of the HandScan with disease activity measures relevant in monitoring treatment response warrants future research focusing on the development of a composite measure to assess disease activity where a joint count assessment (i.e., SJC and TJC) is replaced by OST-scores. OST-scores can be obtained without visiting a physician, as a HandScan measurement can be performed easily by a non-healthcare professional, and at any location where the device can be placed, for example at the out-patient waiting room. By implementing a disease activity index (including only variables which are assessed without visiting a physician, i.a. OST- scores) into daily practice, the rheumatologists’ and/or nurse practitioners’ time might be saved in the busy out-patient-clinics, since only the patients with active disease would require an additional visit to the rheumatologist or healthcare professional for a more detailed assessment, including joint counts. Conclusion A longitudinal association of OST-score with DAS28 exists, although the relation is weak. As such, in this setting OST-score as a single measuring instrument is insufficient to comprehensively assess disease activity in RA patients. However, combining the OST-score with other (routinely used) disease activity parameters might result in an adequate composite disease activity measure.