Nadler 2002.

Methods	RCT; randomised, single (investigator) blind, multicentre study. Stratified randomisation, allocation procedure not described Follow‐up time: 4 days (2 days treatment time)
Participants	Population: 371 participants, 216 women, 155 men. Mean age (SD): 36 (10.59) years Setting: 11 sites, conducted in the USA Inclusion criteria: age 18 to 55 years, acute nonspecific LBP; pain intensity ≥ 2 on 6‐point scale (at least moderate intensity); no low back trauma within the preceding 48 hours; an answer of "yes" to the question "Do the muscles in your low back hurt?" Exclusion criteria: radiculopathy or other neurologic deficits; history of back surgery; fibromyalgia; diabetes mellitus; hypersensitivity for NSAIDs, acetaminophen, or heat; peptic ulcer or gastrointestinal bleedings; renal or hepatic disorders; anticoagulant treatment; pregnancy; daily back pain for more than three consecutive months
Interventions	NSAID (i): ibuprofen 200 mg, 2 tablets t.i.d. + 2 placebo tablets once a day; 2 days (N = 106) Reference treatment (ii): acetaminophen 500 mg, 2 tablets q.i.d.; 2 days (N = 113) Reference treatment (iii): heat wrap, 40 °C, approximately 8 hours of wear per day; 2 days (N = 113) Reference treatment (iv): unheated wrap, 8 hours/day; 2 days (N = 19), no outcome measures presented Reference treatment (v): placebo, 2 tablets q.i.d.; 2 days (N = 20), no outcome measures presented
Outcomes	Pain mean changed score (NRS scale 0 to 5), after 4 days: (i) ‐1.7; (ii) ‐2.0; (iii) ‐2.6; (i) vs (ii) not presented; (i) vs (iii) significantly less effective (P < 0.001) RMDQ (scale 0 to 24, none to maximal disability), mean changed score after 4 days: (i, N = 101) ‐2.7, (ii, N = 104) ‐2.9, (iii, N = 110) ‐4.9; (i) vs (ii) not presented; (i) vs (iii) significantly less effective (P < 0.001) Adverse events: no serious side effects occurred. Systemic adverse events: (i) 10.4% (11/106; 1 withdrew), (ii) 4.4% (5/113), (iii) 6.2% (7/113)
Funding	Funding by the Procter and Gamble company (developer of the used ThermaCare Heat Wrap).
Notes	Declarations of interest: Dr. Nadler is a paid consultant for Procter & Gamble and most of the co‐authors are employees of the Procter and Gamble Health Sciences Institute.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Stratified randomisation, procedure not described
Allocation concealment (selection bias)	Unclear risk	Allocation procedure not described
Blinding of participants and personnel (performance bias) All outcomes ‐ participants	Unclear risk	The participants using tablets (i, ii, v) were blinded for which tablet group they were in; the participants using wraps (iii, iv) were blinded for which wrap they received; but none of them were blinded for both tablets and heat wraps.
Blinding of participants and personnel (performance bias) All outcomes ‐ careproviders	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes ‐ outcome assessors	Low risk	Investigator blinded, data sets determined before the database was unblinded.
Incomplete outcome data (attrition bias) All outcomes ‐ dropouts	Low risk	Low dropout rate: 2.2% (8/371 withdrew)
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis	Unclear risk	ITT analysis performed, but data not presented. Results of ITT population matched the results of the PP populations, so only the evaluable subject population was reported.
Selective reporting (reporting bias)	High risk	Study protocol available, but several data from primary treatment groups were not compared, and results of reference treatment (iv) and (v) were not presented.
Similarity at baseline characteristics	Low risk	Baseline characteristics similar
Co‐interventions avoided or similar	Unclear risk	Subjects were asked not to use other treatments.
Compliance acceptable	Unclear risk	Not mentioned
Timing outcome assessments similar	Low risk	Timing similar
Other bias	Low risk	None