| Methods |
Randomized controlled trial. The method of randomization and the use of blinding are not described. Allocation concealment by sealed, sequentially distributed envelopes. Communication with the author indicated randomization by use of a random number table and blinding of participants, investigators and outcome assessors. |
| Participants |
342 women at public health centers in Iran. Inclusion criteria were married women aged 17 to 40 years who had regular menstrual cycles, no signs and symptoms similar to adverse effects of pills before using them and no prior oral contraceptive use. Exclusion criteria were contraindication to pills, systemic disorders or drug use, breastfeeding, delivery less than 3 weeks previously, use of injectable contraceptive in past 6 months or implant in past 3 months, abnormal Pap smear, abnormal blood cholesterol and triglycerides, and being illiterate. Further exclusion criteria during the study were omitting one or more pills during the cycles, stop taking pills, using other contraceptives along with oral contraceptive pills, acute severe diarrhea and vomiting, and pregnancy. All participants were first‐time oral contraceptive users. |
| Interventions |
Triphasic levonorgestrel/ethinylestradiol (50‐75‐125 µg LNG and 30‐40‐30 µg EE in a 6/5/10 days regimen, N=171) [no brand name described] versus monophasic levonorgestrel/ethinylestradiol (150 µg LNG and 30 µg EE, N=171) [no brand name described]. |
| Outcomes |
Primary outcome measures are: side effects including breakthrough bleeding and spotting; discontinuation and reasons for discontinuation; satisfaction. Use of daily diary method to collect data on side effects. The report does not describe the definitions of breakthrough bleeding and spotting. |
| Notes |
The report does not provide an a priori hypothesis. The paper describes a sample size calculation which referred to both 80% and 85% power. Correspondence with author indicated 80% power. Study duration: 6 cycles. 16 women in the triphasic group and 12 women in the monophasic group discontinued early. Limited information on reasons for discontinuation. 16 women in the triphasic group and 10 women in the monophasic group were lost to follow‐up. Communication with the author gave information that 2 women in the monophasic group discontinued due to nervousness. Analysis not according to intention‐to‐treat principle. The paper does not report information on trial support. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
"Sealed, sequentially distributed envelopes" with letters A, B, C, D (2 letters assigned to each treatment group). Participant chose an envelope, which investigator opened. |
