Titre du document / Document title

Estimating the effectiveness of emergency contraceptive pills

Auteur(s) / Author(s)

TRUSSEL James ⁽¹⁾ ; ELLERTSON Charlotte ⁽²⁾ ; VON HERTZEN Helena ⁽³⁾ ; BIGRIGG Allison ⁽⁴⁾ ; WEBB Anne ⁽³⁾ ; EVANS Margaret ⁽⁵⁾ ; FERDEN Sue ⁽⁶⁾ ; LEADBETTER Clare ⁽⁵⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Office of Population Research, Wallace Hall, Princeton University, Princeton, NJ 08544, ETATS-UNIS
⁽²⁾ Ibis Reproductive Health, Cambridge, MA, ETATS-UNIS
⁽³⁾ Department of Reproductive Health and Research, World Health Organisation, Geneva, SUISSE
⁽⁴⁾ The Sandyford Initiative, Glasgow, Scotland, ROYAUME-UNI
⁽⁵⁾ Abacus Clinic for Contraception and Reproductive Health, Liverpool, ROYAUME-UNI
⁽⁶⁾ Planned Parenthood of Greater Iowa, Des Moines, IA, ETATS-UNIS

Résumé / Abstract

Objective: We use new estimates of conception probabilities by cycle day of intercourse, where cycle day is measured with day I being the first day of bleeding in a cycle, to propose a new approach for estimating the effectiveness of emergency contraceptive pills (ECPs). We use this new approach to examine the absolute effectiveness and the cost-effectiveness of ECPs and whether ECPs are more effective the sooner after unprotected intercourse they are initiated. Methods: Using the new set of conception probabilities, we employ data from two recent clinical trials of ECPs, one from the Population Council and the other from the World Health Organization (WHO), to examine the effectiveness of the combined ECP regimen. Results: The expected pregnancy rate among typical users was 6.2%in the Population Council trial and 7.4%. in the WHO trial based on conception probabilities by cycle day relative to the day of ovulation. Based on conception probabilities by cycle day relative to the first day of bleeding, the expected pregnancy rates dropped to 5.4% and 5.2%, respectively. The two trials yield conflicting evidence regarding whether effectiveness declines with treatment delay. Conclusions: Our results suggest that the absolute levels of effectiveness for the Yuzpe regimen of emergency contraception and the cost-effectiveness of this regimen have probably been overstated when based on conception probabilities by cycle day relative to day of ovulation.

Revue / Journal Title

Contraception   ISSN 0010-7824   CODEN CCPTAY 

Source / Source

2003, vol. 67, n^o4, pp. 259-265 [7 page(s) (article)] (22 ref.)

Langue / Language

Anglais

Editeur / Publisher

Elsevier, New York, NY, ETATS-UNIS  (1970) (Revue)

Mots-clés anglais / English Keywords

Efficiency ; Female ; Human ; Sex steroid hormone ; Progestagen ; Estrogen ; Contraceptive ; Postcoital ; Contraception ;

Mots-clés français / French Keywords

Efficacité ; Femelle ; Homme ; Hormone stéroïde sexuelle ; Progestatif ; Oestrogène ; Contraceptif ; Postcoïtal ; Contraception ;

Mots-clés espagnols / Spanish Keywords

Eficacia ; Hembra ; Hombre ; Hormona esteroide sexual ; Progestágeno ; Estrógeno ; Anticonceptivo ; Postcoital ; Anticoncepción ;

Mots-clés d'auteur / Author Keywords

Emergency contraception ; Effectiveness ;

Localisation / Location

INIST-CNRS, Cote INIST : 15369, 35400011793834.0020