Hancock 2007.

Methods	RCT; randomised, double‐blind, double‐dummy, parallel trial with 4 arms Follow‐up time: 12 weeks (outcomes recorded at baseline, 1, 2, 4, and 12 weeks)
Participants	Population: 240 participants, 105 women and 135 men. Mean age (SD) 40.7 years (15.6); mean duration of current symptoms (SD) 9.13 days (9.31) Setting: 19 GPs from 14 general practices in an urban population in Australia, recruitment between June 2005 and October 2006 Inclusion criteria: all participants with low back pain (with or without leg pain) of less than 6 weeks duration, causing moderate pain and moderate disability (measured by adaptations of items 7 and 8 of SF‐36) Exclusion criteria: present episode of pain not preceded by a pain‐free period of at least 1 month, in which care was not provided; known or suspected serious spinal pathology; nerve root compromise (with at least two of these signs: myotomal weakness, dermatomal sensory loss, or hyporeflexia of the lower limb reflexes); presently taking NSAIDs or undergoing spinal manipulation; any spinal surgery within the preceding 6 months; and contraindication to paracetamol, diclofenac, or spinal manipulative therapy
Interventions	All participants: paracetamol 1g four times daily (until recovery or for a maximum of 4 weeks) and advice given by the GP NSAID (i): diclofenac 50 mg twice daily and placebo manipulative therapy (N = 60) NSAID (ii): diclofenac 50 mg twice daily and spinal manipulative therapy (N = 60) Reference treatment (iii): spinal manipulative therapy and placebo drug twice daily (N = 59; 1 excluded after randomisation) Reference treatment (iv): double placebo (N = 60)
Outcomes	Mean (SD) number of days to recovery, counted as the first pain‐free day (pain score 0 or 1 on range 0 to 10) Hazard ratio of (i) and (ii) vs (iii) and (iv): 1.09 (95% CI 0.84 to 1.42). No significant difference Hazard ratio of (ii) vs (iv): 1.10 (95% CI 0.76 to 1.60, P = 0.609). No significant difference Median days to recovery: (i) and (ii): 13 (95% CI 10 to 16); (iii) and (iv): 16 (95% CI 14 to 18). No significant difference The effects of NSAIDs and spinal manipulative therapy did not interact significantly. Secondary outcomes (pain, disability, function, global perceived effect): no significant differences at any time point Adverse events: total 22 participants (22/239; 9%) (i, ii) 11 participants (1 withdrew); (iii, iv) 11 participants (none withdrew) Additional data retrieved after contacting the author: PI after 14 days, mean NRS (SD): (i, N = 59) 2.32 (2.367); (iii, N = 59) 2.24 (2.003); (iv, N = 60) 2.80 (2.602). No significant differences Disability after 14 days, mean RMDQ (SD): (i, N = 58) 4.86 (5.826); (iii, N = 59) 4.29 (5.408); (iv, N = 60) 5.98 (6.052). No significant differences Global perceived effect after 14 days, mean global perceived effect (SD): (i, N = 59) 3.47 (1.716); (iii, N = 59) 3.73 (1.215); (iv, N = 60) 3.12 (2.059). No significant differences PI after 84 days, mean NRS (SD): (i, N = 57) 1.05 (2.108); (iii, N = 58) 0.98 (2.098); (iv, N = 60) 0.93 (1.903). No significant differences Disability after 84 days, mean RMDQ (SD): (i, N = 57) 2.28 (5.095); (iii, N = 58) 2.03 (4.433); (iv, N = 60) 2.42 (5.093). No significant differences Global perceived effect after 84 days, mean global perceived effect (SD): (i, N = 57) 4.32 (1.638); (iii, N = 58) 4.52 (1.525); (iv, N = 60) 4.35 (1.696). No significant differences
Funding	Funding source (Australia's National Health and Medical Research Council) had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The active diclofenac was donated by Alphapharm (a generic drug manufacturing company based in Australia).
Notes	Declarations of interest: one of the authors was a member of an advisory board about paracetamol for GlaxoSmithKline. Payments went to an audited hospital account for teaching and research purposes.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation schedule developed by statistician not involved in data collection or analysis.
Allocation concealment (selection bias)	Low risk	Sequentially numbered sealed opaque envelopes
Blinding of participants and personnel (performance bias) All outcomes ‐ participants	Low risk	Participants were blinded
Blinding of participants and personnel (performance bias) All outcomes ‐ careproviders	High risk	GPs were blinded, but the physiotherapist who would give either active or placebo spinal manipulative therapy could obviously not be blinded.
Blinding of outcome assessment (detection bias) All outcomes ‐ outcome assessors	Low risk	Outcome assessor was blinded
Incomplete outcome data (attrition bias) All outcomes ‐ dropouts	Low risk	Low dropout rate (< 20% dropouts)
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis	Low risk	ITT analysis was performed; the authors mentioned five participants who did not get the correct spinal manipulative therapy intervention as allocated.
Selective reporting (reporting bias)	Low risk	Trial was registered and study protocol was published.
Similarity at baseline characteristics	Low risk	Baseline characteristics similar
Co‐interventions avoided or similar	Low risk	Co‐interventions similar in the active and placebo arms. Participants were asked not to seek other treatments for their acute LBP during intervention and follow‐up, and a record of additional treatments was kept for any participants who took other treatments within this time.
Compliance acceptable	Low risk	Compliance was acceptable. Unused medications were collected and compliance was assessed using various methods.
Timing outcome assessments similar	Low risk	Timing of outcome assessments similar
Other bias	Low risk	None