Ling 1999.

Study characteristics
Methods	Trial design: double‐blind, randomised, parallel‐group, placebo‐controlled trial
Participants	Participants: 100 women were randomised; 95 women were analysed. Mean age:  Depot leuprolide group: 32.3 years, placebo group 29.4 years Inclusion criteria: Moderate‐to‐severe chronic pelvic pain for at least 6 months, with severity being assessed by a physician using the four‐point Biberoglu and Behrman scale, and that pain was unrelated to menstruation and incompletely relieved with nonsteroidal anti‐inflammatory drugs.  Regular menstrual bleeding and menstrual cycles for 3 months before enrolment Women who had not been sterilised surgically agreed to use barrier contraception during treatment and for 6 weeks thereafter. Exclusion criteria:  A previous diagnosis of endometriosis confirmed by laparoscopy, laparotomy, or histology Had received oral contraceptives (OCs) within the previous 3 months or GnRH agonists within the previous 6 months Had undergone surgical treatment for endometriosis Chronic pelvic pain might be related to genitourinary disease or to chronic or recurrent gastrointestinal disease, including irritable bowel syndrome (defined as a disease characterised by pain relieved by defecation and irregular defecation patterns lasting at least 3 months) Histories of alcohol use or other chronic tranquiliser or illicit drug use Setting: United States of America (12 sites) Timing: June 1995 to January 1997
Interventions	Depot leuprolide injection every 4 weeks, for 3 injections (n = 50) versus Placebo injections every 4 weeks, for 3 injections (n = 50)
Outcomes	Relief of overall pain: pain scores, dysmenorrhoea, pelvic pain, pelvic tenderness, deep dyspareunia, and pelvic induration AFS score Adverse effects
Notes	Intention‐to‐treat analysis: not stated Sample size calculation: not stated Funding: This study was supported by a grant from TAP Holdings, Inc., which distributes depot leuprolide.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The randomisation schedules were prepared in random blocks of two and four, with treatment group assignment in a 1:1 ratio. Each group was represented once within each block of two and twice within each block of four. The schedules were prepared by an administrative staff member using a FORTRAN program to generate uniform random numbers.
Allocation concealment (selection bias)	Low risk	Study medication was packaged according to the randomisation schedules and was sent to each site in sets of four, as needed. Patient numbers were sequential within each set. Patient number assignment started with the lowest available number for each site and proceeded in ascending order. The randomisation schedules were kept in one appropriate, secure place. The blind was not broken until enrolment and classification for evaluable patient analyses were complete.
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	In placebo group, 46/50 completed study. Noncompliance = 1 Patient request = 1 Lost to follow‐up =1 Other =1 In leuprolide depot group, 49/50 completed study. Noncompliance = 1
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