Magos 1986.

Methods	Randomized double blind placebo‐controlled parallel trial
Participants	Women aged 25 to 45 years, with regular periods and confirmed PMS on at least 1 of the 6 clusters in the MDQ during prospective daily symptom ratings.
Interventions	Subcutaneous oestradiol implants versus placebo, 33 women given 100 mg subcutaneous oestradiol implant with 5 mg oral norethisterone for 7 days per cycle. 35 women given placebo implant with 5 mg placebo for 7 days per cycle. Duration: 2 consecutive cycles.
Outcomes	Daily score rating Visual analogue scale of feeling unwell General Health Questionnaire Withdrawal from the study and side effects (e.g. mastalgia, nausea, weight gain).
Notes	Trial was conducted in the UK and sponsored by a King's College Voluntary Research Trust.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number table
Allocation concealment (selection bias)	Low risk	Independent physician concealed the allocation
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Identical looking implants used, dispensed by independent physician
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Patient‐reported scores
Incomplete outcome data (attrition bias) All outcomes	High risk	20% of patients lost to follow‐up due to incomplete data
Selective reporting (reporting bias)	Low risk	All expected outcomes were reported
Other bias	Low risk	All data reported, no specific reasons to suspect other bias