Zippel 2007.

Methods	RCT, double‐blind (non‐inferiority study) Follow‐up time: 2 days
Participants	Population: 370 participants, 202 women and 168 men; mean age ± SD (range): dexketoprofen group: 48.5 ± 13.31 (21 to 75), diclofenac group: 50.0 ± 13.26 (20 to 74) Setting: multicentre trial conducted in 21 centres in Belgium, Germany, and Poland Inclusion: male/female outpatients aged 18 to 75 years with acute low back pain of moderate to severe intensity (≥ 50 mm on a visual analogue scale (VAS)), and of no more than 1 week's duration Exclusion: low back pain secondary to systemic or degenerative diseases, vertebral fractures or compressions; intervertebral disc hernia; neoplastic, infectious or metabolic diseases; and neurological pain. General contraindications to the use of NSAIDs. Concomitant treatment with steroidal drugs, alternative therapies, and use of any analgesic within 6 hours prior to inclusion in the study
Interventions	NSAID (i): dexketoprofen 50 mg IM (Menarini, Florence, Italy), twice daily; 2 days (N = 183) NSAID (ii): diclofenac 75 mg IM (Voltarol®, Novartis Pharmaceuticals Ltd, Horsham, West Sussex, UK), twice daily; 2 days (N = 187)
Outcomes	Outcomes in ITT population Mean (± SD) changes in sum of analogue pain intensity difference scores (SAPID0‐6) from baseline to 6 hours after the first dose 111.8 ± 116.54 (i) versus 112.7 ± 105.71 (ii). Adjusted mean 111.9 (i) and 112.7 (ii); Adjusted ratio of means 0.993. 95% lower CI (two‐sided) 0.79 Adjusted mean SAPID0‐last score was 296.0 mm/h in (i) and 283.8 mm/h in (ii), with no statistical differences between treatments (P = 0.567). The median change in RDQ scores was ‐6.0 for both treatment groups (P = 0.695), showing an improvement on the disability scale Rescue medication: taken by 39% of participants in (i) and 33% of participants in (ii), no statistical differences between treatments (P = 0.235) Adverse events: (i) 50/183 = 27% (4 participants withdrew), (ii) 58/187 = 31% (2 participants withdrew)
Funding	Financially supported by a grant from Menarini Ricerche SpA, Florence, Italy (manufacturer of dexketoprofen). Not mentioned if they had a role in study design, data collection, or analysis.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	participants were randomly assigned according to a computer‐generated randomisation schedule.
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes ‐ participants	Low risk	Study drugs were administered by a person from outside the investigational team. It was not mentioned if they were similar in size, shape, and colour.
Blinding of participants and personnel (performance bias) All outcomes ‐ careproviders	Unclear risk	Study drugs were administered by a person from outside the investigational team. It was unclear if this was their own careprovider.
Blinding of outcome assessment (detection bias) All outcomes ‐ outcome assessors	Low risk	Study drugs were administered by a person from outside the investigational team in order to maintain the double‐blind nature of the study.
Incomplete outcome data (attrition bias) All outcomes ‐ dropouts	Low risk	(i) 10/173 participants withdrew, (ii) 10/177 participants withdrew
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis	Low risk	ITT analysis performed
Selective reporting (reporting bias)	Unclear risk	Trial registration not mentioned
Similarity at baseline characteristics	Low risk	Baseline characteristics similar
Co‐interventions avoided or similar	Low risk	Paracetamol 500 mg, maximum 3g a day, was used as rescue medication.
Compliance acceptable	Unclear risk	Compliance was not mentioned, (unused) study medication was not collected.
Timing outcome assessments similar	Low risk	Timing similar
Other bias	Low risk	None

b.i.d. = twice a day; CI = confidence interval; CRF = case report form; FU = follow‐up; GI = gastrointestinal; GP = general practitioner; IM = intramuscular; ITT = intention‐to‐treat; IV = intravenous; LBP = low back pain; MRI = magnetic resonance imaging; NRS = numeric rating scale; NSAID = non‐steroidal anti‐inflammatory drug; PI = pain intensity; PP = per protocol; QBPDS = Quebec Back Pain Disability Scale; RCT = randomised controlled trial; RMDQ = Roland‐Morris Disability Questionnaire; q.i.d.= four times a day; ROM = range of motion; SD = standard deviation; SLR = straight‐leg raise; SF‐12/36 = 12 or 36‐item Short Form Health Survey; t.i.d. = three times a day; VAS = visual analogue scale; wks = weeks