Andrade 1993.

Methods	Randomized controlled trial without blinding. The method of randomization and the use of allocation concealment are not described. We were unable to reach the author.
Participants	480 women at 14 study sites in Europe and New Zealand. Inclusion criteria were healthy women under 40 years of age who were at risk of becoming pregnant and had regular 21 to 35 day menstrual cycles. The report does not provide exclusion criteria for the study. Switchers were included in the study.
Interventions	Triphasic gestodene/ethinylestradiol (50‐70‐100 μg GTD and 30‐40‐30 μg EE in a 6/5/10 days regimen, N=250 for 6 cycles of whom N=13 continued for an additional 6 cycles) [no brand name described] versus monophasic desogestrel/ethinylestradiol (150 μg DSG and 30 μg EE for 21 days, N=230 for 6 cycles of whom N=8 continued for an additional 6 cycles) [no brand name described].
Outcomes	Principal outcome measures are: pregnancy; cycle control; cycle length and bleeding intensity; side effects; laboratory and cytology changes; blood pressure; bodyweight; compliance; discontinuation and reasons for discontinuation. The method to collect data is not described. The report does not describe the definitions of breakthrough bleeding and spotting.
Notes	The report does not describe an a priori hypothesis or sample size or power calculation. Study duration: 6 and 12 cycles. 49 women in the triphasic group and 50 women in the monophasic group discontinued early. The reasons for discontinuation are described. 7 women in the triphasic group and 5 women in the monophasic group were lost to follow up. 6 women in the triphasic group and 8 women in the monophasic group were withdrawn because of protocol violations. Women who missed pills in cycle 6 were excluded from analysis of cycle control. Analysis not according to intention‐to‐treat principle. The paper does not report information on support.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	No information