Okun 1982

Methods	RCT
Participants	Setting: Cedars‐Sinai Medical Center, Los Angeles, California, USA (assumed from affiliation). Inclusion criteria: hospitalised women with moderate, severe or very severe pain due to uterine cramps or episiotomy within 48 hours of delivery (94 women in total with episiotomy pain) Exclusion criteria: breastfeeding; receipt of any analgesic, sedative or psychotropic medication within 6 hours before administration of the study drug
Interventions	Aspirin (N = 20 randomised) 650 mg aspirin; single oral dose of 2 x 325 mg identical looking capsules Placebo (N = 18 randomised) Placebo; single oral dose of 2 identical looking capsules
Outcomes	Adequate pain relief as reported by the woman: 1 nurse observer recorded pain intensity hourly for 8 hours; intensity was rated from 1 to 5 (1 = no pain; 2 = mild pain; 3 = moderate pain; 4 = severe pain; 5 = very severe pain); pain intensity differences were calculated, as were SPID scores at 4, 6, and 8 hours; the time of maximum pain relief; duration of pain relief; the proportion of women with at least 50% pain relief 1 and 2 hours after treatment Need for additional pain relief in the first 48 hours for perineal pain: proportion requiring additional analgesics Adverse effects: adverse effects mentioned by women were recorded No data included in the meta‐analyses as results were not reported separately for women with post‐episiotomy pain
Notes	Funding: not reported Declarations of interests: not reported Additional arms: this was a 5‐arm trial also assessed fendosal 100 (N = 19), 200 (N = 19) and 400 mg (N = 18); we included only the relevant arms in this review Note: trial also included women with postpartum uterine cramps pain; not included in review (157/250); no data were able to be included in the meta‐analyses as results were not reported separately for women with post‐episiotomy pain
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Assignment to treatment was randomised"
Allocation concealment (selection bias)	Unclear risk	No detail provided
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quotes: "double‐blind" and "identical looking capsules"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	As above; 1 nurse observer recorded the pain intensity scores prior and hourly after administration of medication, reasonable to assume that outcome assessment is blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	A total of 250 eligible women were "admitted to the study"… "The PI scores from patients taking another analgesic were handled as treatment failures by substituting the initial PI score for all hours after the analgesic was taken"
Selective reporting (reporting bias)	Unclear risk	Results (such as SPID scores) were reported incompletely in text
Other bias	Low risk	Baseline characteristics (such as initial intensity and type of pain; age and weight) were comparable between groups