Mohamed 2011.

Methods	Randomized trial conducted at Kasr El‐Aini Hospital in Cairo, Egypt between 01 May 2008 and 31 July 2010.
Participants	600 women. Inclusion criteria: 17 to 42 years of age, at risk of becoming pregnant, regular menstrual cycles, seeking contraception. Exclusion criteria: contraindications for contraceptive steroid use, use of injectable hormonal contraceptive in past 6 months, use of hormonal IUD or other hormonal contraceptive in past 2 months, abortion or breastfeeding within 2 months before starting trial medication. Also excluded if abnormal cervical smear was diagnosed during screening and prolapse of the uterine cervix, cystocele, or rectocele was diagnosed before or during screening.
Interventions	1) NuvaRing (N=300), releasing etonogestrel 120 µg + EE 15 µg daily 2) COC (drospirenone 3 mg + EE 30 μg) Duration: 12 consecutive cycles with each treatment cycle consisting of 3 weeks of ring or pill treatment followed by 1‐week ring‐free or pill‐free period. Women were seen 5 times: at screening visit and within 1 week after the ring‐free or pill‐free periods of cycles 3, 6, 9, and 12 or at premature discontinuation.
Outcomes	Cycle control (via diary cards) Withdrawal bleeding: 'none' presented as indicator of amenorrhea Breakthrough bleeding or spotting: any bleeding or spotting that occurred during the periods of ring or pill use. early, during first 10 days; midcycle, on day 11; late, during last 10 days of ring or pill use. Adverse events, reported by participants or observed by physician during examination. Particular attention to blood pressure, acne, body weight, and vaginal discharge. Metabolic effects (not included in this review)
Notes	Unable to obtain information from investigator regarding randomization, allocation concealment, and funding. Also requested data on AEs and bleeding for all study women; report only provides data on women who completed the study. Discontinued due to AE: 27 ring and 19 COC women.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomized in 1:1 ratio
Allocation concealment (selection bias)	Unclear risk	Not provided.
Blinding (performance bias and detection bias) All outcomes	High risk	Open‐label
Incomplete outcome data (attrition bias) All outcomes	High risk	Lost to follow up: 65/600 (11%); ring 32/300 (11%); COC 33/300 (11%). Excluded those who discontinued due to AE and other reasons. unspecified AE: ring, 27/300 (9%); COC, 17/300 (6%). other reasons: ring, desire for pregnancy 2/300 (0.7%); COC, pregnancy 2/300 (0.7%) and desire for pregnancy 3/300 (1%).