title: Contraceptive efficacy of a combined oral contraceptive containing ethinyloestradiol 20 μg/drospirenone 3mg administered in a 24/4 regimen: a pooled analysis of four open-label studies.
abstract: OBJECTIVE
  To determine the contraceptive efficacy of a low-dose combined oral contraceptive containing ethinyloestradiol (EE) 20 μg/drospirenone (drsp) 3mg administered for 24 days followed by a four-day hormone-free interval (24/4 regimen), by pooling data from four clinical trials.
  
  
  METHODS
  Data on the occurrence of pregnancy during treatment in four open-label trials that enrolled healthy female volunteers aged 17-36 years, who received EE 20 μg/drsp 3mg in a 24/4 regimen for 7 or 13 cycles, were pooled.
  
  
  RESULTS
  Sixteen pregnancies occurred among 2386 women during 729,537 days (26,055 cycles) of treatment exposure, resulting in a Pearl Index (PI) of 0.80 (upper two-sided 95% confidence interval (CI) limit of 1.30). Of these pregnancies, seven were defined as method failures, resulting in an adjusted PI of 0.41 (upper two-sided 95% CI limit of 0.85), based on 616,607 days (22,022 cycles) of treatment. The Kaplan-Meier estimate for the one-year cumulative probability of contraceptive protection was 99.21%.
  
  
  CONCLUSIONS
  The EE 20 μg/drsp 3mg combined oral contraceptive administered in a 24/4 regimen has acceptable contraceptive efficacy.
authors.affiliation: The Family Federation of Finland, Turku Clinic, Turku, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: Anttila
authors.forename: Gloria
authors.initials: G
authors.lastname: Bachmann
authors.forename: László
authors.initials: L
authors.lastname: Hernádi
authors.forename: Michael
authors.initials: M
authors.lastname: Kunz
authors.forename: Joachim
authors.initials: J
authors.lastname: Marr
authors.forename: Christine
authors.initials: C
authors.lastname: Klipping
mesh_terms: D000293:Adolescent; D000328:Adult; D000736:Androstenes / Q000008:administration & dosage / Q000627:therapeutic use*; D003277:Contraceptives, Oral, Combined / Q000008:administration & dosage / Q000627:therapeutic use*; D004967:Estrogens / Q000008:administration & dosage / Q000627:therapeutic use*; D004997:Ethinyl Estradiol / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D055118:Medication Adherence; D011247:Pregnancy; D018873:Pregnancy Rate; D011372:Progestins / Q000008:administration & dosage / Q000627:therapeutic use*; D013223:Statistics as Topic; D055815:Young Adult
chemical_list: D000736:Androstenes; D003277:Contraceptives, Oral, Combined; D004967:Estrogens; D011372:Progestins; D004997:Ethinyl Estradiol; C035144:drospirenone