Kauppila 1979.

Methods	Trial design: 2‐period, 4‐treatment cross‐over trial
Participants	24 women randomised; 18 analysed Mean age: 33 (22‐43) years Inclusion criteria: women with symptomatic endometriosis (stage and severity not described). Endometriosis was diagnosed by laparoscopy (n = 13) and by pelvic examination (n = 5). Exclusion criteria: not clear Setting: Finland Timing: unclear
Interventions	Group 1: indomethacin 25 mg given 3 × daily for 2 menstrual cycles, then cross‐over to acetylsalicylic acid, tolfenamic acid and placebo for 2 menstrual cycles each (n = 6) Group 2: acetylsalicylic acid 500 mg given 3 × daily for 2 menstrual cycles, then cross‐over to tolfenamic acid, placebo and indomethacin for 2 menstrual cycles each (n = 6) Group 3: tolfenamic acid 200 mg given 3 × daily for 2 menstrual cycles, then cross‐over to placebo, indomethacin and acetylsalicylic acid for 2 menstrual cycles each (n = 6) Group 4: placebo given 3 × daily for 2 menstrual cycles, then cross‐over to indomethacin, acetylsalicylic acid and tolfenamic acid for 2 menstrual cycles each (n = 6)
Outcomes	These were self‐reported by questionnaire, which was completed by the participant immediately after each menstrual cycle. Pain relief: pelvic pain, lower back pain, pain in walking, dyspareunia, pain on defecation, headache; number not reported but described as more common with placebo and indomethacin Quality of life: not reported Effect on daily activities: not reported Absence from work or school: not reported Unintended effects of treatment: gastrointestinal complaints (nausea and vomiting), number not reported but described as more common with indomethacin; psychic complaints (insomnia and nervousness), number not reported but described as more common with indomethacin Number of women requiring more invasive treatment: not reported Requirements for additional medication: not reported Participant satisfaction with treatment: not reported
Notes	Drugs for use in the trial were provided by Medica Ltd, Helsinki, Finland. "The authors wish to thank Medica Ltd, Helsinki, Finland, for the drugs."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	"placebo‐controlled double‐blind trial"
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Twenty‐four patients...volunteered for this study. Eighteen women completed the trial; the remaining six terminated treatment for a variety of personal reasons."
Selective reporting (reporting bias)	Unclear risk	Prespecified primary and secondary outcomes were not clearly defined.
Other bias	Unclear risk	Insufficient information was provided to enable a judgement of low risk of bias.