Brown 1986.

Methods	RCT; open‐label. Randomisation procedure not described Follow‐up time: 15 days
Participants	Population: 47 participants, 22 women, 18 men. Mean age 29 years (range 18 to 59) Setting: University of Maryland Health Center Inclusion criteria: initial or recurrent mild to moderate acute LBP, age 18 to 59 years Exclusion criteria: pregnant or nursing women, allergy to aspirin or other NSAIDs, history of peptic ulcer, gastrointestinal bleeding or bleeding disorders, significant hypertension; cardiovascular, renal, or hepatic disease, recurrent chronic pain, neurologic signs or symptoms, fracture of the lumbosacral spine
Interventions	NSAID (i): diflunisal (500 mg tablets), initial dose 2 tablets (1000 mg), followed by 1 tablet (500 mg) every 12 hrs, 15 days (N = 19) Reference treatment (ii): acetaminophen with codeine (300 mg + 30 mg tablets), initial dose 2 tablets (660 mg), followed by 1 tablet (330 mg) every 4 hours, 15 days (N = 21)
Outcomes	Pain assessments by participant and investigator on 3‐point ordinal scale showed similar improvement curves (data in graphs) No. of participants rating drugs as excellent or very good (i) 9 (ii) 9. No significant differences Side effects: more side effects in (ii) 10 (in 5 participants) than in (i) 3 (in 3 participants). No participants withdrew because of side effects.
Funding	Study supported by a grant from Merck Sharp & Dohme (developer of diflunisal)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation procedure not described
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes ‐ participants	High risk	Not blinded
Blinding of participants and personnel (performance bias) All outcomes ‐ careproviders	High risk	Not blinded
Blinding of outcome assessment (detection bias) All outcomes ‐ outcome assessors	Low risk	Study co‐ordinator dispensed all medications and was not involved in participant evaluation. None of the investigators were aware of the medication taken by the participant.
Incomplete outcome data (attrition bias) All outcomes ‐ dropouts	Low risk	Dropout rate 14.8% (7/47) 7 participants were withdrawn because they failed to return for follow‐up evaluation.
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis	High risk	No ITT analysis performed
Selective reporting (reporting bias)	Unclear risk	No study protocol
Similarity at baseline characteristics	Unclear risk	No table with baseline characteristics
Co‐interventions avoided or similar	Low risk	No other analgesic/anti‐inflammatory treatment was allowed. Each participant did the same postural exercises from day 3 on.
Compliance acceptable	Unclear risk	Compliance not mentioned
Timing outcome assessments similar	Unclear risk	Timing similar
Other bias	Low risk	None