Freundl 1998.

Study characteristics
Methods	Trial design: randomised, double‐blind, comparative study
Participants	Participants: 27 women were randomised and analysed. Mean age: group A: 35 ± 5 years, group P: 34.8 ± 5 years Inclusion criteria: Age between 18‐45 Endometriosis score greater than 5 points causing symptoms and/or sterility  Normal bone density prior to medication Use of contraceptive devices in the 1st month of treatment Exclusion criteria: not stated  Setting: Germany Timing: not stated
Interventions	Group A: received a combination of leuprorelin acetate depot with 20 mg ethinyloestradiol plus 0.15 mg desogestrel (n = 14) versus Group P: received leuprorelin acetate depot plus placebo (n = 13)
Outcomes	Relief of overall pain: endometriosis symptoms Bone mineral density Hypooestrogenic symptoms rAFS score Blood/urine chemistry Body weight
Notes	Intention‐to‐treat analysis: not stated Sample size calculation: not stated Funding: not stated Contact with the author could not be established for further information; he unfortunately passed away.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Prospective double‐blind, randomised placebo‐controlled trial". 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‐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