Gnoth 1999.

Study characteristics
Methods	Trial design: Randomised, double‐blind, placebo‐controlled, prospective trial
Participants	Participants: 27 women were randomised and analysed. Mean age: group 1; 34.8 ± 5 years, group 2; 35 ± 5 years Inclusion criteria: Laparoscopically confirmed endometriosis (rAFS I‐IV) No hormonal pretreatment at least 8 weeks prior to study entry Age 18‐45 Normal bone mineral density prior to study entry Exclusion criteria:  Reduced bone mineral density prior to study entry Absolute or relative contraindication against ethinyl oestradiol or desogestrel Pregnancy Medical history or any event of thrombosis Any form of haemoglobin disorders, hypertension, liver function disorders, any history of malignant diseases, any oestrogen‐related disorders like otosclerosis, herpes gestationis, history of severe pruritus in pregnancy  Additional medication with: antiepileptics, antibiotics, rifampicin, isoniazid, phenylbutazon, griseofulvin, chlorpromazin, nitrofurantoin or dihydroergotamin Setting: Germany Timing: not stated
Interventions	Group 1: leuprolin acetate 3.75 mg IM + oral placebo each day versus Group 2: leuprolin acetate 3.75 mg IM + 20μg ethinyl oestrodiol and 0.15 mg desogestrel per day
Outcomes	Bone mineral density Pyridinoline concentrations in urine Calcium: serum and urinary concentrations
Notes	Intention‐to‐treat analysis: not stated Sample size calculation: not stated Funding: not stated Author contacted for more information regarding selection bias; awaiting response
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	By centralised randomisation process. No further details of method used to generate the randomisation sequence were provided.
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‐blinded, placebo‐controlled study
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blinded, placebo‐controlled study
Incomplete outcome data (attrition bias) All outcomes	Low risk	Pretreatment measurements of one women weres not done. 1 early pregnancy post‐treatment. The reply from the authors stated that there were no exclusions post‐randomisation or losses to follow‐up, but remarked that one woman withdrew directly after the first medical investigation and randomisation. She did not tell the reasons for her decision. There were no measurements taken from her. This participant was completely excluded from the evaluation and replaced.
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