All fertile-aged women (15-49 years) living in Finland in 2017 and using
hormonal contraception in 2017 and their 1:1 age- and residence-matched controls not using
hormonal contraception in 2017 (altogether 587 559 women) were selected from the Prescription Centre. All incident
venous thromboembolism cases during 2018-2019 and their 4:1 age-matched controls were further analyzed in a prospective nested case-control design to assess the associations between the use (starting, stopping, continuous vs no use) of different
hormonal contraception types and
venous thromboembolism.
RESULTS: Altogether, 1334
venous thromboembolism cases occurred during the follow-up period (incidence rate 1.14 per 1000 person-years, 95% confidence interval [CI] 1.08-1.20), with an incidence rate ratio of
hormonal contraception vs no
hormonal contraception use of 1.42 (95% CI 1.27-1.58). Compared with non-use, starting the use of
gestodene and ethinylestradiol (adjusted odds ratio [aOR] 2.85; 95% CI 1.62-5.03),
drospirenone and ethinylestradiol (aOR 1.55; 95% CI 0.98-2.44),
desogestrel and ethinylestradiol (aOR 1.97; 95% CI 0.99-3.92), and
transdermal patch releasing
norelgestromin and ethinylestradiol (aOR 5.10; 95% CI 1.12-23.16), as well as continuing the use of
gestodene and ethinylestradiol (aOR 2.60; 95% CI 1.61-4.21),
drospirenone and ethinylestradiol (aOR 1.55; 95% CI 1.02-2.37),
cyproterone-acetate and
estrogen/ethinylestradiol (aOR 1.66; 95% CI 1.06-2.61), and
vaginal ring releasing
etonogestrel and ethinylestradiol (aOR 3.27; 95% CI 1.95-5.48) were associated with
venous thromboembolism risk. Regarding the type of
estrogen, the highest risk was associated with current use (vs non use in the previous 180 days) of ethinylestradiol-containing preparations (aOR 2.20; 95% CI 1.82-2.65), followed by
estradiol-containing preparations (aOR 1.39; 95% CI 1.04-1.87) with no risk for
progestin-only
hormonal contraception. Current use of
estradiol-containing preparations was not associated with
venous thromboembolism risk after exclusion of
cyproterone-acetate and
estrogen/ethinylestradiol (aOR 1.05; 95% CI 0.66-1.66).
CONCLUSIONS: