Maxime Verhoeven

188 Chapter 10 METHODS This study used 2 cohorts. For model development and internal validation, routinely collected data from electronic medical records of the rheumatology department of Máxima Medical Center (MMC) Eindhoven were used and for external validation, data of the ACURA Rheumatology Center Bad Kreuznach (ACURA). The institutional ethical review board of MMC indicated that the Medical Research Involving Human Subject Act (WMO) was not applicable as no interventions or extra measurements were performed and only pseudonymised routinely collected data was extracted frommedical records. As such patients did not gave informed consent. The local standing committee for ethical conduct of Rhineland-Palatinate, Germany, has approved the study of the ACURA cohort and patients gave written informed consent. Development and internal validation cohort Patients with RA, visiting the out-patient-clinic at MMC from April 2017 up to and including March 2019 were eligible for inclusion. Inclusion criteria were; (1) RA according to the American college of Rheumatology (ACR) 1987 or ACR/ European League against Rheumatism (EULAR) 2010 criteria, (2) no relevant visual deformations of hands or fingers (invalid HandScan measurement), (3) availability of a DAS28 measurement, with, thereafter, a HandScan measurement, performed during the same clinical visit, (4) age above 18 years, and (5) no participation in interventional studies. 7 DAS28 was performed without knowledge of the HandScan score. External validation cohort OST was performed in eligible RA patients during their stay in the ACURA in-patient- clinic from September 2017 up to and including June 2018. All included patients met the 2010 ACR/EULAR classification criteria for RA. 9 Patients with age<18 years, joint prostheses/implants, severe hand deformities, pronounced ulnar deviation, recent trauma or surgery and known photosensitivity were excluded. Assessments Data of DAS28 components (SJC28, TJC28, ESR and patient VAS), age, gender, disease duration, rheumatoid factor (RF) status, and anti-cyclic citrullinated peptide (anti-CCP) status were extracted, if available. OST-scores (i.e., total score and individual score of 22 joints) were obtained directly from the HandScan device. Data up to March 2019 was extracted. Data on the same variables was collected in the ACURA cohort. In both cohorts, DAS28 scores were assessed by a well-trained person, blinded with respect to OST-score. Inflammation markers, CRP and/or ESR, were routinely tested and used for DAS28 calculation. RF and anti-CCP status were assessed by ELISA.