Background Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep venous thrombosis (DVT), can be life threatening. An increased frequency of VTE has been found in inflammatory conditions. To date, evidence assessing whether this risk is also greater in patients with ankylosing spondylitis (AS) is scarce.
Methods Using the provincial British Columbia, Canada healthcare database that encompasses all residents within the province, we conducted matched cohort analyses of incident PE, DVT and overall VTE among incident cases of AS and compared them with individuals randomly selected from the general population without AS. We calculated incidence rates (IRs) of VTE and multivariable analyses after adjusting for traditional risk factors using Cox models.
Results Among 7190 incident cases of AS, 35 developed PE and 47 developed DVT. IRs of PE, DVT and overall VTE per 1000 person-years for patients with AS were 0.79, 1.06, 1.56 compared with 0.40, 0.50, 0.77 in the control cohort. Corresponding fully adjusted HRs (95% CI) of PE, DVT and VTE were 1.36 (0.92 to 1.99), 1.62 (1.16 to 2.26) and 1.53 (1.16 to 2.01), respectively. The risks of PE, DVT and VTE were highest in the first year of diagnosis with HR (95% CI) of 2.88 (0.87 to 9.62), 2.20 (0.80 to 6.03) and 2.10 (0.88 to 4.99), respectively.
Conclusions These findings demonstrate an increased risk of VTE in the general AS population. This risk appears the most prominent in the first year after diagnosis.
- venous thromboembolism
- deep venous thrombosis
- pulmonary embolism
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Handling editor Josef S Smolen
Contributors JAA-Z (corresponding author) was responsible for applying and securing the funds for the project. He was also involved in the planning of the study design and statistical analysis, and he reviewed the study manuscript. He takes responsibility for the data and integrity of the paper. JC contributed to the project by taking part in the planning of the statistical analysis, as well as writing and compiling the study manuscript. MDV was involved in the planning of the study design and review of the study manuscript. ECS was the statistical analyst who carried out the analysis and reviewed the study manuscript. HC contributed to the fund application process and took part in the planning of the study design. He also reviewed the study manuscript. JE contributed to the fund application process and critically reviewed the manuscript.
Funding This study was funded by grants from the Canadian Arthritis Network, The Arthritis Society of Canada, the British Columbia Lupus Society (Grant 10-SRP-IJD-01) and the Canadian Institutes for Health Research (Grants MOP 125960 and THC 135235). JAA-Z is the British Columbia Lupus Research Scholar and holds a salary award from the Michael Smith Foundation for Health Research. MDV is a tier 2 Canada Research Chair in Medication Adherence, Utilization, and Outcomes and holds a salary award from the Michael Smith Foundation for Health Research.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethics approval was obtained from the University of British Columbia.
Provenance and peer review Not commissioned; externally peer reviewed.
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