Bloomfield 1974.

Study characteristics
Methods	RCT
Participants	Setting: University of Cincinnati Medical Center, Ohio, USA (assumed from author affiliation) Trial dates: not reported (published in 1974) Inclusion criteria: healthy postpartum women with moderate to very severe episiotomy pain (mediolateral or midline) within 48 hours of an otherwise uncomplicated birth Exclusion criteria: mild pain; unmarried, aged < 18 years; history of aspirin allergy; given analgesics, sedatives, or other psychotropic drugs within the previous 6 hours; breastfeeding; known drug dependence
Interventions	Aspirin (N = 20 randomised) 900 mg aspirin; single oral dose of 3 tablets of 300 mg each Placebo (N = 20 randomised) Lactose placebo; single oral dose of 3 tablets All women: stilbestrol and ferrous sulphate were given routinely during the postpartum period, however all other drugs were avoided unless necessary, and except for "cleansing", all perineal care was suspended for the 6‐hour study period; women were confined to bed for the first 2 hours and were intermittently out of bed during the last 4 hours. Tablets were administered on demand, with a full glass of water, at approximately the same time of the day throughout the study (2 hours before breakfast) and women were instructed to lie on their right sides for 2 hours afterwards
Outcomes	Adequate pain relief as reported by the woman: the same trained nurse observer interviewed women hourly for 6 hours; women estimated the severity of 'stitch' pain on a scale of 0 to 4 (0 = no pain; 1 = mild pain; 2 = medium pain; 3 = severe pain; 4 = very severe pain): Pain intensity difference scores were calculated by the difference between a woman's pre‐treatment pain intensity score and early hourly post‐treatment score; these scores (equivalent to SPID scores), presented in Figure 4 in the manuscript, were used to calculate 'Adequate pain relief as reported by the woman' (taken over 6 hours) Number of women with pain reduction > 50% at any time during the 6 hours was also reported Need for additional pain relief in the first 48 hours for perineal pain: request for additional analgesic medication (codeine or propoxyphene) before the end of the 6‐hour study period Maternal adverse effects: side effects were elicited spontaneously at final interview "with a minimum use of leading questions and without invoking a checklist of possible side effects"
Notes	Funding: "Supported in part by United States Public Health Service Grant No. HL‐05622 and by the Upjohn Company. Supplies of ibuprofen and other coded medications were provided by Carter D. Brooks, M.D., The Upjohn Company" Declarations of interests: not reported Additional trial arms: this was a 4‐arm trial also assessing ibuprofen 300 mg (N = 20) and 900 mg (N = 20); we only included the relevant arms in this review
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "On entering the study patients were randomly allocated to one of the 4 groups according to a predetermined schedule. The randomization provided for stratification of patients on the basis of initial intensity of pain"
Allocation concealment (selection bias)	Unclear risk	Not detailed
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quotes: "double‐blind conditions"... "All were in the form of film‐coated tablets identical in appearance and taste, and were prepackaged in code‐numbered individual dose vials"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Changes in pain intensity and side effects associated with the treatments were evaluated subjectively in uniformly conducted interviews"; reasonable to assume blinding of women and interviewer
Incomplete outcome data (attrition bias) All outcomes	High risk	No losses or exclusions reported; assumed only 80 women randomised, and all included in analyses; 4 women requested additional analgesic (3 in the placebo group); their pain relief data before additional analgesics were given were included in the analysis, but interviews were then discontinued, and for the remaining hours, each woman’s pain intensity score was adjusted to the value of her pre‐treatment score. Imputation of data likely to have influenced results
Selective reporting (reporting bias)	Unclear risk	Very limited outcome data; no access to trial registration or protocol to further assess selective reporting
Other bias	Low risk	Baseline characteristics comparable for relevant groups ("Two exceptions were a preponderance of unmarried patients in the ibuprofen 300 mg group compared with the 3 other groups, and body weight, which in the group of patients receiving ibuprofen 900 mg was distinctly higher than in patients in the other 3 groups. These were chance occurrences with an uncertain influence on the results"); no other obvious risk of bias identified