The Study
Esterified estrogens and conjugated equine estrogens and the risk of venous thrombosis.
This study found that women who took one kind of hormone (conjugated equine estrogen) seemed to have more blood clots than those who didn’t take hormones or took a different kind. But it can’t prove the hormone caused the clots — maybe other things were different between the groups.
Analysis score
Maximum 58 for a case-control study.
Where the score came from
Some hormone pills for menopause might raise the chance of blood clots, but not all of them.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 555 / 100
Quality score
Researchers compare people who have a condition (cases) with similar people who do not (controls), looking back in time for differences in exposure. Useful but more prone to bias.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — a 65% to 78% increase in risk is large enough to matter for individual health decisions.
- 2Women taking conjugated equine estrogen had a 65% higher chance of first blood clot than women not taking hormones.
- 3Women taking esterified estrogen had no higher chance.
- 4Among women taking estrogen, those on conjugated equine estrogen had a 78% higher chance than those on esterified estrogen.
- 5Higher doses of conjugated equine estrogen meant higher risk.
- 6Adding progestin raised risk by 60%.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
JAMA
Year
2004
Authors
N. Smith, S. Heckbert, R. Lemaitre, A. Reiner, T. Lumley, N. Weiss, E. Larson, F. Rosendaal, B. Psaty
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.