Background/Purpose:

Venous thromboembolism (VTE)(pulmonary embolism [PE] and deep vein thrombosis[DVT]) is a potentially life threatening disease. Previous hospital-based studies have shown an increased risk of VTE in patients with ankylosing spondylitis (AS) but limited population-based data are available. We estimated the population-based risk of newly recorded PE and DVT among incident cases with AS compared with controls from the general population using physician-billing and hospitalization databases that cover the entire population of the province of British Columbia, Canada (~5 million)

Methods:

Our data includes all visits to health professionals and all hospital admissions from Jan 1, 1996 to Dec 31, 2012 and all dispensed medications from Sept 1, 1996 to Dec 31, 2012 for all individuals. We conducted a retrospective matched cohort study of all patients >18 years of age satisfying the following criteria: 1) two ICD-9 or 10 codes (720.0 or M45) for AS at least two months apart and within a 2-year period by any physician or hospitalization; 2) all AS cases had at least a 7-year run-in period before the 1st ICD code for AS in order to consider the case as incident. Each AS patient was matched with up to 10 controls by birth year, sex, and entry cohort time. We excluded cases that were diagnosed with other inflammatory conditions such as rheumatoid arthritis, vasculitis, myositis, and systemic lupus erythematosus on at least two visits. Ten non-AS controls matched by birth year, sex, and calendar year of follow-up were selected from the general population for each case.

Our outcomes were incident PE and DVT events that were recorded from outpatient visits, hospitalizations, or death certificates. For non-fatal events, we required the use of anticoagulation medications within six-months as part of all outcome definitions. We estimated relative risks (RRs) by comparing those with AS to age, sex, and entry time matched comparison cohorts, adjusting for potential known risk factors for VTE.

Results:

Among 7,190 incident cases of AS (51% male, mean age of 46yrs [SD 15.6]), 35, 47, and 69 developed PE, DVT, or both, respectively (incidence rates= 0.79, 1.06, and 1.56 per 1000 person years, respective) (see table). Compared with age, sex, and entry time matched controls, the RRs were 1.95 (95% CI; 1.36-2.81), 2.19 (95% CI; 1.60-3.00), and 2.06 (95% CI; 1.59-2.68) for PE, DVT, and both, respectively. After adjusting for covariates, the results remained similar (see table 1).

Conclusion:

This large population-based study indicates an increased risk of PE and DVT in patients with AS. Our results support the increased need for awareness and potential monitoring of these complications in AS patients.

Table 1. Relative Risk of Incident PE and DVT according to AS Status

* Fully-adjusted models include the following selected covariates: Glucocorticoid use and number of outpatient visits.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-risk-of-deep-venous-thrombosis-and-pulmonary-embolism-in-ankylosing-spondylitis-a-general-population-based-study/