Comparing the Cardiovascular Risk of Norethindrone Acetate & Levonorgestrel Pills: Is There a Difference? [10I]
Bibliographic record
Abstract
INTRODUCTION: Combined oral contraceptives containing norethindrone acetate (NETA) are widely used in the US and globally, but how they compare to levonorgestrel-containing pills is unknown. This pooled analysis compares the safety of NETA and levonorgestrel (LNG) in pills with ethinyl estradiol (EE) ≤30 mcg. METHODS: We pooled cohorts of NETA (EE ≤30 mcg) and LNG (EE ≤30 mcg) users from four large prospective, controlled, non-interventional, cohort studies in 14 European countries, US and Canada. Baseline characteristics, including reproductive, contraceptive and medical history, were summarized using descriptive statistics. Propensity score sub-classification was applied to balance baseline characteristics between cohorts. Time-to-event analysis of venous and arterial thromboembolic events was carried out based on the extended Cox model to calculate crude and adjusted hazard ratios with 95% confidence intervals. RESULTS: Approximately 80,000 women contributed 145,000 women years of exposure. The prevalence of prognostic factors at baseline showed typical features of US and European oral contraceptive users. A comparison between NETA vs LNG showed no significant difference in the risk of venous thromboembolism: adjusted hazard ratio 0.73 (95% CI 0.48-1.11). A similar result was observed considering the risk of arterial thromboembolism (adjusted hazard ratio 0.89 [95% CI 0.42-1.89]). CONCLUSION: Low-dose oral contraceptives containing NETA and LNG are associated with similar low risks of venous and arterial disease. This analysis provides reassurance for both women and clinicians regarding the safety of contemporary oral contraceptives.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.016 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.004 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".