Article Text
Abstract
Objective To investigate if autoimmune thyroid disease (AITD) impacts rheumatoid arthritis (RA) disease activity or response to methotrexate.
Methods A nationwide register-based cohort study of 9 004 patients with new-onset RA from the Swedish Rheumatology Quality Register year 2006–2016, with linkage to other nationwide registers to identify comorbidity with AITD defined as thyroxine prescription before RA diagnosis, excluding non-autoimmune causes. We compared RA disease activity using 28-joint Disease Activity Score (DAS28) and its components, and EULAR response, between patients with and without AITD, using logistic regression.
Results At diagnosis, patient reported outcome measures (PROMs; patient global, Health Assessment Questionnaire Disability Index and pain) but not objective disease activity measures (erythrocyte sedimentation rate and swollen joint count) were significantly higher (p<0.05 for all PROMs) among RA patients with AITD compared with those without. The level of DAS28 was 5.2 vs 5.1. By contrast, AITD had little influence on EULAR response to methotrexate at 3 months (OR of non/moderate response=0.95, 95% CI 0.8 to 1.1), nor at 6 months. When stratified by age, however, AITD was more common among EULAR non/moderate responders at 3 and 6 months in patients below 45 years resulting in ORs of non/moderate response of 1.44 (0.76–2.76) and 2.75 (1.04–7.28).
Conclusion At diagnosis, RA patients with concomitant AITD score worse on patient reported but not on objective RA disease activity measures, while DAS28 was only marginally elevated. The overall chance of achieving a EULAR good response at 3 or 6 months remains unaffected, although among a limited subgroup of younger patients, AITD may be a predictor for an inferior primary response.
- Arthritis, Rheumatoid
- Autoimmune Diseases
- Methotrexate
- Epidemiology
- Patient Reported Outcome Measures
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Footnotes
Contributors All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be submitted for publication. KW and JA had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study conception and design: KW, JA. Acquisition of data: KW, BD, SS, JA. Analysis and interpretation of data: KW, BD, SS, JA.
Funding This work was supported by research grants from the Swedish Research Council, the Swedish Cancer Society, the Swedish HeartLung Foundation, Nordforsk, Vinnova and FOREUM. Financial support information: Dr Askling has acted or acts as PI in agreements between Karolinska Institutet and the following entities, mainly related to the safety monitoring of immunomodulators in rheumatology: Abbvie, BMS, Eli Lilly, Merck, Pfizer, Roche, Samsung Bioepis, Sanofi.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The Stockholm Regional Ethics Committee approved this study (DNR 2015/1844-31/2).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.