MEASURING TREATMENT RESPONSE IN RHEUMATOID ARTHRITIS The use of patient-reported outcome measures Martine Veehof Thesis, University of Twente, 2008 © Martine Veehof ISBN 978‐90‐365‐2686‐9 Cover design: Gea Bisschop Printed by: Gildeprint B.V., Enschede The studies presented in this thesis were performed at the department of Psychology & Communication of Health & Risk (PCHR) of the University of Twente (Enschede) and the departments of Rheumatology of the “Medisch Spectrum Twente” hospital (Enschede) and the hospitals of “Ziekenhuisgroep Twente” (Almelo and Hengelo). The rheumatology research program of PCHR is financially supported by the Dutch Arthritis Association (Reumafonds). Parts of this thesis were financially supported by an unrestricted educational grant by Schering‐Plough, CVZ (Health Care Insurance Board), “Stichting Reumaonderzoek Twente”, and the European Union. MEASURING TREATMENT RESPONSE IN RHEUMATOID ARTHRITIS The use of patient‐reported outcome measures PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit Twente, op gezag van de rector magnificus, prof. dr. W.H.M. Zijm, volgens besluit van het College voor Promoties in het openbaar te verdedigen op donderdag 26 juni 2008 om 15.00 uur door Martine Maria Veehof geboren op 4 januari 1976 te Enschede Dit proefschrift is goedgekeurd door de promotor, prof. dr. M.A.F.J. van de Laar en de assistent‐promotor, dr. E. Taal. Promotiecommissie: Promotor: Prof. dr. M.A.F.J. van de Laar Assistent‐promotor: Dr. E. Taal Leden: Prof. dr. J. Dekker, Vrije Universiteit Amsterdam Prof. dr. J.M.W. Hazes, Erasmus Universiteit Rotterdam Prof. dr. J.M.J.P. van der Linden, Universiteit Maastricht Prof. dr. J.S. Rietman, Universiteit Twente Prof. dr. E.R. Seydel, Universiteit Twente Contents 1 General introduction 9 2 Comparison of internal and external responsiveness of the generic 23 Medical Outcome Study Short Form‐36 (SF‐36) with disease‐specific measures in rheumatoid arthritis 3 Psychometric properties of the Rheumatoid Arthritis Disease 41 Activity Index (RADAI) in a cohort of consecutive Dutch patients with RA starting anti‐tumour necrosis factor treatment 4 Determinants of the use of wrist working splints in rheumatoid 57 arthritis 5 The efficacy of wrist working splints in rheumatoid arthritis: a 73 randomized controlled study 6 What determines the possession of assistive devices among patients 91 with rheumatic diseases? The influence of the country‐related health care system 7 Possession of assistive devices is related to improved psychological 107 well‐being in patients with rheumatic conditions 8 Summary and general conclusions 121 Samenvatting (Dutch summary) 129 Dank! (Acknowledgements) 139 Curriculum Vitae & List of Publications 143 1 General introduction Chapter 1 Rheumatoid arthritis (RA) is a chronic inflammatory joint disease of unknown etiology that affects approximately 1% of the adult population, with a higher prevalence observed in both older age groups and women. The disease is characterized by symmetric inflammation of the joints, particularly of the wrists, fingers and feet, leading to pain, swelling, stiffness and, in the longer term, to joint damage. More general symptoms are fatigue and morning stiffness. All of these symptoms may contribute to reduced functional ability and dependency upon others, both of which are important concerns for patients with RA.1‐3 Furthermore, psychological and social well‐ being may be reduced. The course of RA is unpredictable, and there is wide variation in its severity. Periods of exacerbation and remission of disease activity may alternate. Treatment of RA primarily focuses on relieving symptoms, reducing inflammation, controlling joint damage, and maintaining or improving functional ability and psychosocial functioning. Presently, the ultimate treatment goal is remission of disease activity. There are convincing data suggesting that a stable remission prevents joint damage and functional disability. Although the efficacy of pharmacological treatments has increased rapidly over the past years, RA is still a progressive disease that leads to joint damage and functional disability in a considerable number of patients.4 Therefore, in addition to drug treatment, non‐pharmacological treatment remains necessary for some patients in order to cope with the consequences of the disease.5,6 Non‐ pharmacological treatment encompasses a wide range of interventions, including physical exercises, joint protection strategies, orthoses, assistive devices, and psychological and self‐management interventions. To justify these interventions from health care and health economic perspectives, it is necessary to assess their effects. Obviously, and in contrast to recently developed medications, evidence regarding responses to non‐pharmacological treatment interventions is limited.6,7 To assess the response to treatment, reliable, valid, and responsive outcome measures are required. A distinction can be made between clinical outcome measures, including laboratory and radiographic assessments, and patient‐reported outcome measures. The latter have become increasingly important in assessing the effects of treatment as they assess the burden of the disease from the patient’s perspective. This thesis is divided into three main parts. The first part focuses on the psychometric properties of commonly used patient‐reported outcome measures in RA. The second and third parts focus on the effects of non‐pharmacological interventions, with an emphasis on the use of orthoses and assistive devices, respectively. In this general introduction, the major themes and aims of the thesis are elucidated, and an outline of the thesis is given. ‐10 ‐
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