Venous thrombosis risk of combined pills varies

Clinical question: 
What is the risk of venous thrombosis (VT) in women using different combined oral contraceptives (COCs)?
Bottom line: 
All individual types of COC increased thrombosis risk more than 2-fold compared with non-use. The effect size depended both on the progestogen used and the dose of ethinyloestradiol. Risk of VT for COCs with 30-35µg ethinyloestradiol and gestodene, desogestrel, cyproterone acetate and drospirenone were similar, and about 50-80% higher than with levonorgestrel. The COC with the lowest risk was 30µg ethinyloestradiol with levonorgestrel. All combined monophasic oral contraceptive pills had the same effectiveness.
Studies of women on postmenopausal hormone replacement therapy, women taking non-oral or progestogen-only contraceptives, and those with VT recurrence were excluded. VT was objectively confirmed in all patients in only a few studies.
COC use has been associated with deep VT and pulmonary embolism. The VT risk has been evaluated for many oestrogen doses and progestogen types contained in COCs but no comprehensive comparison involving commonly used COCs is available.
Review CD#: 
March, 2014
Authored by: 
Brian R McAvoy