Garcia 2017.

Study characteristics
Methods	Study design: RCT (NCT02123394) Setting: Brazil, healthcare Exercise groups: 1 Comparison groups: 1
Participants	Number of participants: 148 (E1 = 74, C1 = 73) Chronic LBP duration: 41.68 months (long) Neurological/radicular symptoms: No participants Mean age (years): 56 Sex (female): 76%
Interventions	Exercise Group 1 (E1): McKenzie method of mechanical diagnosis and therapy, repeated exercises with patient specific direction (3 possible treatment groups: derangement, dysfunction, postural); type = McKenzie; duration = 5 weeks; dose = low; design = individualised; delivery = individual; additional intervention = advice/education Comparison Group 1 (C1): Placebo: disconnected ultrasound and diathermy
Outcomes	Core outcomes reported: Pain (Numerical Rating Scale); function (Roland‐Morris Disability Questionnaire) Follow‐up time periods available for syntheses: 13 weeks (short); 26 weeks (moderate); 52 weeks (long)
Notes	Conflicts of interest: The care provider who treated patients in the MDT group has completed first level McKenzie training, however has no involvement with the McKenzie Institute. This trial did not receive either funding from McKenzie Institute or any assistance in writing/analysing the results of this trial. Authors do not have any involvement with the McKenzie Institute. MJH, LOPC and ANG receive funding from International Mechanical Diagnosis and Therapy Research Foundation for the following studies on MDT: (1) Hancock MJ, Maher CG, Mota da Silva T, Clare H, Steffens D (2016). Secondary prevention of a recurrence of low back pain. (2) Hancock MJ, Garcia AN, Costa LdCM, Costa LOP (2014). Identifying patients with back pain who respond best to MDT. MJH was keynote speaker at the 2017 McKenzie conference and his travel costs were paid. Funding source: São Paulo Research Foundation; Coordination for the Improvement of Higher Education Personnel Other: Information modified for author contact
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"A simple randomisation schedule was computer generated".
Allocation concealment (selection bias)	Low risk	"The allocation was concealed by using consecutive numbered, sealed and opaque envelopes".
Blinding of participants and personnel (performance bias) All outcomes	Low risk	1. No patients were not truly blinded to the treatment they received; 2. Unlikely that patients deviated as study attempted to keep them unaware of the intervention received by other group; also hard to access the McKenzie Method of Mechanical Diagnosis and Therapy outside of study.
Blinding of care provider (performance bias)	Low risk	1. Care providers could not be blinded to allocation due to the nature of the treatments; 2. Interventions were conducted by different physiotherapists, treatments were audited by authors, minimal decision‐making by therapist
Blinding of outcome assessment (detection bias) All outcomes	Low risk	1. Outcomes in question were assessed by the patient who are not blinded to the intervention; 2. Attempted to keep patients unaware of intervention received by other group
Incomplete outcome data (attrition bias) All outcomes	Low risk	1. One of 147 was effectively zero at the 3‐month mark.
Participants analysed in group allocated (attrition bias)	Low risk	1. Intention‐to‐treat analysis was used in this study.
Selective reporting (reporting bias)	Low risk	1. Study was analysed and reported according to registered protocol (NCT02123394).
Groups similar at baseline (selection bias)	Low risk	Groups were similar on all relevant characteristics at baseline.
Co‐interventions avoided or similar (performance bias)	Low risk	Co‐intervention use was tracked and compared between groups; there were no significant differences between groups on co‐intervention use.
Compliance acceptable in all groups (performance bias)	Low risk	Out of 10 sessions that could be completed, the patients allocated to the McKenzie Method of Mechanical Diagnosis and Therapy group attended a mean of 9.01 sessions compared with a mean of 9.23 sessions for patients allocated to the placebo group.
Timing of outcome assessment similar in all groups (detection bias)	Low risk	1. Outcome assessments were identical for all patients, regardless of treatment group; 2. Numeric Rating Scale (for pain) and Roland‐Morris Disability Questionnaire (for function) are well‐validated tools in the low back pain context.
Other bias	Low risk	There were no other sources of bias noticed; generally well‐reported.