Hornstein 1998.

Study characteristics
Methods	Trial design: Multi‐centre randomised, double‐blind, placebo‐controlled trial
Participants	Participants: 201 women were randomised and analysed. Mean age: Group A: 28.4 ± 6.1, group B: 28.7 ± 6.2, group C: 29.0 ± 5.6, group D: 27.9 ± 5.7 Inclusion criteria: Women Aged 18‐43 Regular menstrual cycles History of symptomatic endometriosis diagnosed surgically within 12 months of study entry Persistent or recurrent pain Exclusion criteria: not stated Setting: United States of America Timing: not stated
Interventions	All patients received GnRH agonist (Lupron depot 3.75 mg every 4 weeks for 52 weeks) and calcium supplementation as elemental calcium 1000 mg daily.  Group A: received daily oral placebos for progestin and oestrogen (n = 51) Group B: received daily oral norethindrone acetate 5 mg with placebo for oestrogen (n = 55) Group C: received norethindrone 5 mg and conjugated equine oestrogens 0.625 mg (n = 47) Group D: received norethindrone 5 mg and conjugated equine oestrogens 1.25 mg (n = 48)
Outcomes	Relief of overall pain Bone mineral density Serum lipid analyses Adverse effects
Notes	Intention‐to‐treat analysis: not stated Sample size calculation: yes Funding: Grant received from TAP Pharmaceuticals Inc. Ms Castro is a paid employee of TAP Pharmaceuticals Inc; Dr Weissberg was a paid employee of TAP Pharmaceuticals Inc. at the time the study was undertaken. Drs Hornstein and Surrey have received honoraria for participating in a limited number of lectureships and symposias sponsored by TAP Pharmaceuticals Inc.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Patients were assigned randomly to a treatment group by permuted blocks of four at each of 26 study sites.
Allocation concealment (selection bias)	Unclear risk	No details of method used to conceal allocation were provided.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, placebo‐controlled study
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blind, placebo‐controlled study
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up
Selective reporting (reporting bias)	Low risk	The study protocol was not available but it was clear that the published reports included all expected outcomes, including those that were prespecified.
Other bias	Low risk	No other risk of bias detected