Miki 2018.

Methods	RCT; open‐label, non‐inferiority trial. Computer‐generated randomisation Follow‐up time: 4 weeks
Participants	Population: 127 participants, 84 women, 43 men. Mean age (SD) (i) 66.73 (2.29) (ii) 63.5 (19.4) Setting: 1 outpatient hospital in Japan, recruitment from July 2014 until September 2017 Inclusion criteria: age older than 20 years old and initiation of LBP in the 4 weeks prior to study entry Exclusion criteria: seeking a second opinion for a prior consultation, cancer‐related pain, presence of neurological symptoms (e.g. pain radiating down the leg), traumatic cases, such as falls, evidence of bone fractures, surgery within the prior 6 months, current use of full, regularly recommended doses of an analgesic, pregnancy, autoimmune diseases, inflammatory rheumatic disordered, cardiopulmonary restrictions, severe kidney or liver function disorders, acute duodenal or ventricular ulcer, psychiatric disorders, or the presence of laboratory data outside the normal limits
Interventions	NSAID (i): loxoprofen 60 mg, 3 times daily; 4 weeks (N = 63) Reference treatment (ii): acetaminophen 600 mg, 4 times daily; 4 weeks (N = 64)
Outcomes	Pain difference mean changed score, NRS, after 2 weeks: (i) vs (ii) ‐0.51 (95% CI ‐1.70 to 0.67), not significant. After 4 weeks: (i, N = 35) vs (ii, N = 35) ‐0.80 (95% CI ‐2.08 to 0.48), not significant Adverse events: (i) 1 participant (GI complaints); (ii) 5 participants (of which 3 GI complaints)
Funding	The study was funded by a Japanese association for the study of musculoskeletal pain.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation
Allocation concealment (selection bias)	Low risk	The randomisation procedure was performed by a person not involved in the treatment of participants.
Blinding of participants and personnel (performance bias) All outcomes ‐ participants	High risk	Not blinded; open‐label trial
Blinding of participants and personnel (performance bias) All outcomes ‐ careproviders	High risk	Not blinded; open‐label trial
Blinding of outcome assessment (detection bias) All outcomes ‐ outcome assessors	High risk	Additional information by authors: treatment was performed by a single orthopaedist, and outcomes were assessed by the same physician.
Incomplete outcome data (attrition bias) All outcomes ‐ dropouts	High risk	High dropout rate 44.9% (57/127 withdrew)
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis	High risk	No ITT analysis, only a PP analysis performed
Selective reporting (reporting bias)	Unclear risk	Trial was registered at local ethics committee; (inter)national trial registry not mentioned. The primary outcome pain intensity (NRS) after 2 and 4 weeks was not presented clearly in the results section of the article.
Similarity at baseline characteristics	Low risk	Baseline characteristics similar
Co‐interventions avoided or similar	Unclear risk	External medication for pain was not allowed, with the exception of topical anaesthetics. No other supplementary analgesic medication was given during the treatment period.
Compliance acceptable	High risk	Additional information by authors: compliance was not measured. Participants were told that they could stop the medication if their symptoms improved, or if any adverse events occurred.
Timing outcome assessments similar	Low risk	Timing similar
Other bias	Low risk	None