Machado 2010.

Study characteristics
Methods	Study design: multi‐centre randomized controlled trial Setting: 27 medical practices located in a socioeconomically diverse region in Sydney, Australia
Participants	Acute/subacute population Inclusion criteria: patients had to be 18‐80 years old, present with a new episode of acute non‐specific low back pain (< 6 weeks duration) and to be able and willing to visit one of the trial physical therapists for commencement of the McKenzie treatment program within 48 hours of presentation to the physician. Exclusion criteria: patients with nerve root compromise, “red flags” for spinal pathology, spinal surgery in the past 6 months, pregnancy, severe cardiovascular or metabolic disease, or the inability to read and understand English. N = 148: treatment group = 73; control group = 73 Age, mean (SD) years: treatment group = 47.5 (14.4); control group = 45.9 (14.9) Sex (N): treatment group = 38 female, 35 male; control group = 35 female, 38 male
Interventions	Treatment group: McKenzie method ‐ in addition to the first‐line care, physical therapists were instructed to follow exclusively the treatment principles described in McKenzie’s textbooks. For most participants, the guiding treatment principle was to encourage directions of movement and postures that produced centralization of pain. The number of treatment sessions was at the discretion of the physical therapist, with a maximum of 6 sessions over 3 weeks. Participants were also encouraged to perform the prescribed exercises at home and to follow the therapist’s postural advice at all times. A copy of the Treat Your Own Back book was provided to all participants. Some participants also received a lumbar support (original McKenzie lumbar roll) at the therapist’s discretion. Control group: first‐line care ‐ based on guideline recommendations that consisted of the provision of advice to remain active and to avoid bed rest, reassurance of the favourable prognosis of acute low back pain and instructions to take acetaminophen (paracetamol) on a time contingent basis. Participants were instructed to follow the physician’s advice for the next 3 weeks and, if necessary, to return for follow‐up visits during this period.
Outcomes	Pain (NRS) Disability (RMDQ) Timing of assessments: 1 week and 3 weeks
Notes	Treatment was provided by physical therapists who had achieved the status of credentialed in McKenzie methods.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer‐generated randomisation sequence was used (randomisation permuted blocks of 4, 6 and 8)
Allocation concealment (selection bias)	Low risk	Sequentially, numbered, sealed and opaque envelopes were used.
Blinding (performance bias and detection bias) All outcomes	High risk	The index and control groups are distinguishable for the patients.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The index and control groups are distinguishable for the care providers.
Blinding of outcome assessment (detection bias) All outcomes	High risk	The primary outcomes are self‐reported outcomes, in which the patient (unblinded) is the outcome assessor.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The maximum number of participants lost to follow‐up in any time was 8 (5%)
Intention to treat analysis	Low risk	Data were analysed according to the intention to treat principles.
Selective reporting (reporting bias)	Low risk	All of the study's pre‐specified outcomes in the protocol have been reported.
Group similarity at baseline	Low risk	All demographic and clinical characteristics were similar between groups.
Co‐interventions	Low risk	Co‐interventions were equally applied across both groups.
Compliance	Low risk	Adherence rates were 66% over the first week and 74% over the treatment period.
Timing of outcome assessment	Low risk	Participants in both groups were evaluated at same time.
Other bias	Low risk	Free of other sources of bias