Bloomfield 1986a.

Study characteristics
Methods	Randomised controlled trial
Participants	Setting: single‐centre study at Cincinnati General Hospital ‐ time frame not given Inclusion criteria: hospitalised postpartum women, 18 years or older with an uncomplicated birth and moderate or severe uterine cramps Exclusion criteria: women who experienced episiotomy pain greater than their uterine cramp pain; women with history of hypersensitivity to aspirin or codeine; women given analgesics, sedatives or other psychotropic within previous 6 hours; known drug dependence; women breastfeeding their babies
Interventions	Women were randomly allocated to 1 of 5 treatment groups, stratified by initial pain intensity, moderate or severe, and given a single oral dose (2 capsules) of 1 of the following. Flurbiprofen 50 mg (2 capsules flurbiprofen 25 mg) (N = 30) Aspirin 650 mg (2 capsules aspirin 325 mg) (N = 34) Codeine sulfate 60 mg (1 capsule codeine sulfate 60 mg, 1 capsule placebo) (N = 32) Codeine sulfate 120 mg (2 capsules codeine sulfate 60 mg) (N = 31) Placebo (2 capsules placebo of unknown composition) (N = 32)
Outcomes	Adequate pain relief as assessed by the woman: pain assessed by 1 of 2 trained nurse observers before the 1st dose and at ½hour or hourly intervals for 6 hours Women were asked to rate pain intensity and pain relief on a 4‐point scale; none (0), slight (1), moderate (2), severe or complete relief (3). From the initial observation the pain intensity difference and sum of pain intensity difference and sum of pain relief were calculated. Reported SPID scores were used to calculate 'adequate pain relief as assessed by the woman' (estimated over 6 hours) Need for additional analgesia: women requiring greater pain relief were removed from the study and given medication as needed, they were not interviewed further. Data for these women were included in the analysis Maternal side effects: side effects elicited were graded on a 4‐point verbal ordinal rating scale of severity with minimal use of leading questions
Notes	Quote: "The pain intensity score for each unperformed interview was adjusted to the pretreatment value, and the adjusted scores were analysed" Dates of study: not stated. Funding sources: study funded in part by grant from pharmaceutical company Upjohn Declarations of interest: no declaration of interests statement
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Women were "randomly assigned". "On enrolment. patients underwent a two‐way stratification according to morning or afternoon shifts of the two clinical nurse observers, and according to moderate or severe pretreatment pain intensity" Unclear exactly how random sequence was generated
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The study was double‐blind, the participant and the caregiver. Medications were "pre packed, code numbered", and were identical in appearance and taste
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data on all women randomised have been included in the reported outcomes. There were 30 women allocated to the flurbiprofen group, 34 women to the aspirin group, 32 women to each of the codeine 120mg group and placebo, and 321 women to the codeine 60mg group, including appropriately‐estimated data for the 9 women who withdrew. Five women from the placebo group, two women from the aspirin group and one woman each from the two codeine groups were withdrawn so that they could receive rescue analgesia. These women were not interviewed about pain following withdrawn. Subsequent pain intensity scores were adjusted to their pretreatment score and used in the analysis
Selective reporting (reporting bias)	Unclear risk	No published protocol or trial registration available
Other bias	Low risk	No other risk of bias identified