Hassan 2017.

Study characteristics
Methods	Randomised controlled clinical trial Duration and location of the trial: quote: "This was a balanced, randomized (allocation ratio 1:1), parallel group trial conducted in Cairo and Beni‐Suef University Hospitals from May 2013 to January 2015.“
Participants	Inclusion criteria: women included in the trial had CC‐resistant PCOS, and were aged 20–40 years. PCOS was diagnosed according to the Rotterdam 2003 criteria. CC resistance was defined as failure of ovulation despite receiving 150 mg of CC for 5 days during successive menstrual cycles for 3 months. Exclusion criteria: other causes of infertility, BMI> 35 kg/m², hyperprolactinaemia, allergy to FSH, and previous use of FSH or letrozole therapies. Number of women randomised: 140, 70 to each group Number of women analysed: 140, 70 in each group Number of withdrawals/exclusions/loss to follow‐up and reasons: 3 women in the letrozole group and 2 women in the uFSH group were lost to follow‐up; ITT analysis was adopted in which these participants were considered anovulatory in the 3 cycles. Number of centres: 2‐centre trial Age (y): letrozole group 28.7 ± 6.2, uFSH group 30.0 ± 5.6 BMI (kg/m²): letrozole group 27.6 ± 4.1, uFSH group 27.2 ± 3.8 Duration of infertility (y): letrozole group 4.9 ± 2.1, uFSH group 5.2 ± 2.2 Country: Cairo University and Beni‐Suef University Hospitals, Egypt
Interventions	Group A: quote: "group 1 received letrozole (Femara VR, Novartis, Basel, Switzerland) 2.5 mg twice daily for five days starting from the third day of menstruation or progesterone withdrawal bleeding." Group B: quote: "group 2 received uFSH (Fostimon VR IBSA, Geneva, Switzerland). To minimize the risk of multiple pregnancy and OHSS, we used a low‐dose FSH setup regimen. The starting daily dose of uFSH was 75 IU for seven days starting from the third day of menstruation or progesterone withdrawal bleeding. If the follicular diameter did not exceed 9 mm, the daily dose was increased by 37.5 IU every seven days. The cycle was cancelled if no follicles exceeded 9 mm by four weeks after starting FSH."
Outcomes	Cumulative clinical pregnancy, defined as the presence of an intrauterine gestational sac 5 weeks after timed intercourse Secondary outcomes were ovulation, miscarriage and possible drug side effects, i.e. OHSS, headache, dizziness, hot flushes, nausea, vomiting or constipation
Notes	Ethical approval: the trial was approved by the research ethics committees of both institutions. Informed consent: written informed consent was obtained Source of funding: quote: "The study was self‐funded" Power calculation: quote: "The required sample size was estimated using PS Power and Sample Size Calculations software, version 3.0.11 for Microsoft Windows. We needed to study 64 women receiving letrozole and 64 women receiving uFSH for three cycles to be able to reject the null hypothesis that the pregnancy rates for letrozole and uFSH in CC‐resistant women were equal, with a probability (power) of 0.9."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	An independent individual generated the allocation sequence using computer‐generated random numbers
Allocation concealment (selection bias)	Low risk	Allocation was concealed using sequentially‐numbered opaque sealed envelopes
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants randomised were also analysed
Selective reporting (reporting bias)	Low risk	All expected outcomes were reported
Other bias	Low risk	None