Bloomfield 1967

Methods	RCT
Participants	Setting: Cincinnati General Hospital, Ohio, USA Date: December 1965 to April 1966 Inclusion criteria: women with a painful ('moderate' or 'severe') mediolateral episiotomy, within 24 hours following an uncomplicated labour and birth. Exclusion criteria: breastfeeding; aged < 18 years; known aspirin sensitivity; 'mild' pain at interview within 24 hours of birth.
Interventions	Aspirin (N = 17 randomised) 600 mg aspirin; women received a single oral dose in a black capsule Placebo (N = 18 randomised) Women received a single oral dose in a black capsule All women: women did not receive other analgesics during the 6 hours of study or during the 6 hours before entering the study
Outcomes	Adequate pain relief as reported by the woman: pain intensity evaluated by 1 research nurse hourly for 6 hours; women were asked "How much do your stiches hurt you?", and answers were transposed into an ordinal scale from 0 to 3 (0 = no pain; 1 = slight pain; 2 = moderate pain; 3 = severe pain). The difference between a woman's pre‐treatment pain intensity score and each hourly post‐treatment score gave an hourly pain relief score; a total 6 hour pain relief score was calculated for each woman by adding these scores. Mean Pain Relief scores (equivalent to SPID scores) were used to calculate 'Adequate pain relief as reported by the woman' (taken over 6 hours) Maternal adverse effects: women were asked on the day following treatment whether they noticed any other effects of the treatment; if they answered 'yes' they were asked 'What were they'; no leading questions were asked
Notes	Funding: the study was supported in part by USPHS grants HE 05622 and HE 07392 from the National Institutes of Health Declarations of interest: not reported (short ‘About the authors’ section describing affiliations) Additional trial arms: this was a 5‐arm trial, also assessing chlorphenesin 400 mg (N = 18), 800 mg (N = 17) and combination aspirin 300 mg and chlorphenesin 400 mg (N = 18); we included only the relevant arms in this review
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "were randomly assigned... according to a predetermined schedule"
Allocation concealment (selection bias)	Unclear risk	Not detailed
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quotes: "double‐blind"; and "All patients received a single dose of coded mediation by mouth in identical black capsules". Assumed that blinding of women and personnel was successful with the use of an identical placebo
Blinding of outcome assessment (detection bias) All outcomes	Low risk	1 research nurse evaluated pain intensity and side effects by interviewing women. Assumed that blinding of the research nurse and women was successful with the use of an identical placebo
Incomplete outcome data (attrition bias) All outcomes	High risk	88 women had moderate or severe episiotomy pain; 84 completed the 6 hours of study and "form the basis of this report"… "Four of the 88 patients entering the trial were withdrawn owing to distressing pain unrelieved by the study drugs" (1/17 from the aspirin group; 0/18 from the placebo group)
Selective reporting (reporting bias)	Unclear risk	Very few outcomes reported (pain relief and side effects only); no access to trial registration or protocol to further assess selective reporting
Other bias	Low risk	Baseline characteristics were comparable between groups; no other obvious risk of bias identified