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Risk of venous thromboembolism in rheumatoid arthritis, and its association with disease activity: a nationwide cohort study from Sweden
  1. Viktor Molander1,2,
  2. Hannah Bower1,
  3. Thomas Frisell1,
  4. Johan Askling1,2
  1. 1Clinical Epidemiology Division, Karolinska Institutet, Stockholm, Sweden
  2. 2Rheumatology, Karolinska University Hospital, Stockholm, Sweden
  1. Correspondence to Dr Viktor Molander, Clinical Epidemiology Division, Karolinska Institutet, Stockholm, Sweden; viktor.molander{at}


Objective To assess the incidence of venous thromboembolism (VTE) in rheumatoid arthritis (RA) relative to individuals without RA, and to investigate the relationship between aspects of clinical disease activity in RA and the risk of VTE.

Methods We conducted a nationwide register-based cohort study 2006 through 2018 using the Swedish Rheumatology Quality Register linked to other national patient registers to identify all patients with RA with at least one registered rheumatologist visit during the study period (n=46 316 patients, 322 601 visits). The Disease Activity Score 28 erythrocyte sedimentation rate (ESR) (DAS28 ESR) and its components served as the exposure, and a VTE event within the year following the visit was the main outcome. We also included general population referents (1:5) matched on age, sex and residential area.

Results Based on 2241 incident VTE events within 1 year of each included visit, and 5301 VTE events in the general population cohort, the risk ratio for VTE in RA was 1.88 (95% CI 1.65 to 2.15). Among patients with RA, the risk (and risk ratio) increased with increasing RA disease activity, from 0.52% following visits in remission to 1.08% following visits with DAS28 ESR high disease activity, RR compared with remission=2.03, 95% CI 1.73 to 2.38. Compared with the general population, also patients with RA in DAS28 ESR remission were at elevated VTE risk.

Conclusions This study demonstrates a strong association between clinical RA disease activity measured by DAS28 ESR and the risk of VTE. RA disease activity can be used as an additional tool for VTE risk stratification in patients with RA.

  • arthritis
  • rheumatoid
  • cardiovascular diseases
  • epidemiology
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  • Handling editor Josef S Smolen

  • Correction notice This article has been corrected since it published Online First. Table 2 has been increased in size for clarity.

  • Contributors All authors participated in the design of the study. HB conducted the statistical analyses. VM, HB, TF and JA contributed to interpretation of the results. VM and JA contributed to the drafting of the manuscript. All authors contributed to the critical revision of the manuscript for important intellectual content. The study was supervised by JA.

  • Funding This study has received funding from Swedish Research Council, the Swedish Heart Lung Foundation, The Swedish Cancer Society, and the Karolinska Institutet Region Stockholm funds (ALF).

  • Disclaimer Funders had no impact on the design or interpretation of the study or its results.

  • Competing interests Karolinska Institutet, with JA as principal investigator, has or has had research agreements with Abbvie, Astra-Zeneca, BMS, Eli Lilly, MSD, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB, mainly in the context of safety monitoring of biologics via ARTIS/Swedish Biologics Register.

  • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

  • Patient consent for publication Not required.

  • Ethics approval Regional Ethics Committee, Stockholm, Sweden. 2015/1844-31/2.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data may be obtained from a third party and are not publicly available. The study data forms part of a register linkage performed by Karolinska Institutet, and for which further sharing of the data is limited by legal restrictions.

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