Amlie 1987.

Methods	RCT; double‐blind, parallel placebo‐controlled multicentre trial. Randomisation procedure not described Follow‐up time: 7 days
Participants	Population: 282 participants, 116 women, 166 men Setting: 27 GPs, company doctors, and rheumatologists participated in the trial, conducted in Norway Inclusion criteria: acute LBP, onset within the previous 48 hours, free from LBP for the last 3 months, age 18 years to 60 years Exclusion criteria: radicular symptoms, ankylosing spondylitis, rheumatoid arthritis, history of peptic ulcer or severe dyspepsia, hypersensitivity to aspirin or other NSAIDs, pregnancy or lactation; and any other hematologic, hepatic, renal, pulmonary, cardiac, or systemic disease
Interventions	NSAID (i): piroxicam 20 mg capsules, single daily dose of 40 mg (2 capsules) for the first two days, then single daily dose of 20 mg (1 capsule) for the next 5 days; 7 days (N = 140). Reference treatment (ii): placebo capsules, single daily dose of 40 mg (2 capsules) for the first two days, then single daily dose of 20 mg (1 capsule) for the next 5 days; 7 days (N = 142).
Outcomes	(i) More pain relief than (ii) measured with visual analogue scale after 3 days. After 7 days no significant differences Consumption of additional analgesics: (i) 49 (N = 134) versus (ii) 62 (N = 132), with a mean consumption of 3.2 (i) versus 5.9 (ii) tablets after 7 days. Return to work after 7 days: (i) 42 (N = 134) versus (ii) 28 participants. Adverse effects: similar (i) 18 (13%) (ii) 24 (17%)
Funding	Study supported by Pfizer, developer of Piroxicam
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	Low risk	To maintain double‐blind conditions, placebo capsules of identical appearance were administered in the same way as the study drug.
Blinding of participants and personnel (performance bias) All outcomes ‐ careproviders	Low risk	Double‐blind, double‐dummy
Blinding of outcome assessment (detection bias) All outcomes ‐ outcome assessors	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes ‐ dropouts	Low risk	Low dropout rate: 5,6%. (i) 6/140 withdrew. (ii) 10/142 withdrew. (16/242)
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	Low risk	Baseline characteristics similar
Co‐interventions avoided or similar	Low risk	Paracetamol 500 mg, maximum 6 to 8 tablets a day, was used as rescue medication. In a very few cases, a combination of paracetamol and codeine was permitted for more severe pain. The consumption of rescue analgesics was recorded for each participant during the trial.
Compliance acceptable	Unclear risk	Compliance not mentioned; they do mention that 12 withdrawals were due to protocol violations.
Timing outcome assessments similar	Low risk	Timing similar
Other bias	Low risk	None