Abstract
Objective
To investigate the effect of endometriosis on venous thromboembolism (VTE) in oral
contraceptive (OC) users. Pooled analysis on a harmonized dataset compromising international
patient-centric cohort studies: INAS-VIPOS, INAS-SCORE, and INAS-FOCUS. Eleven European
countries, the United States, and Canada. Individuals being newly prescribed an OC
with or without an endometriosis and no VTE history.
Methods
Detailed information was captured using self-administered questionnaires at baseline
and every 6 to 12 months thereafter. Self-reported VTEs were medically validated and
reviewed by an independent adjudication committee. Incidence rates (IRs) were calculated
per 10,000 woman-years. The association of endometriosis on VTE was determined in
a time-to-event analysis, calculating crude and adjusted hazard ratios (HRs) with
95% confidence intervals (CIs) using stabilized inverse probability of treatment weighting
(IPTW).
Results
A total of 22,072 women had an endometriosis diagnosis, and 91,056 women did not.
Women with endometriosis contributed 78,751 woman-years during which 41 VTE events
occurred (IR: 5.2/10,000, 95% CI: 3.7–7.1) compared to 127 VTEs during 310,501 woman-years
in women without endometriosis (IR: 4.1/10,000, 95% CI: 3.4–4.9). The hazard ratio
of VTE in women with endometriosis was 1.79 (95% CI: 1.24–2.57) using stabilized IPTW
controlling for age, body mass index, smoking, education, age at menarche, and family
history of VTE. Subgroup and sensitivity analyses showed similar results.
Conclusion
These results highlight the importance of considering endometriosis as a potential
factor contributing to VTE in women using OC; however, further research on the relationship
between endometriosis and VTE is warranted.
Keywords
endometriosis - venous thromboembolism - oral contraceptive
