Schenk 2003.

Study characteristics
Methods	Study design: randomized controlled trial Setting: hospital‐based outpatient clinic, New York, USA
Participants	Acute/subacute population Inclusion criteria: participants classified with lumbar posterior derangement, aged 21‐76 years old Exclusion criteria: participants classified with lumbar joint dysfunction N = 25: treatment group = 15; control group = 10 Age, mean years: treatment group = 40.1; control group = 44.8 Sex (N): treatment group = 8 female, 7 male; control group = 2 female, 7 male
Interventions	Treatment group: McKenzie method (therapeutic exercises consisted of lumbar extension or lumbar flexion with the hips offset) Control group: joint mobilization (passive movement applied to the spinal segments based on the patient's response to repeated movements and passive mobility testing) The interventions for all subjects consisted of postural correction and ambulation on the treadmill for up to 20 minutes. Subjects in each group performed five sets of ten repetitions of the prescribed exercise or received five sets of ten repetitions of joint mobilization.
Outcomes	Pain (VAS) Disability (ODI) Timing of assessments: 3 weeks
Notes	Participants were treated by the same physical therapist, who was certified in McKenzie method.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer randomization was used
Allocation concealment (selection bias)	High risk	The author was contacted and reported that the process of allocation concealment was carried out by drawing a slip of paper from a box.
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	There were no missing outcome data.
Intention to treat analysis	Low risk	There were no dropout or withdrawals and all patients were analysed in the groups to which they were allocated.
Selective reporting (reporting bias)	Unclear risk	No protocol available and the report does not include enough information to make this judgement.
Group similarity at baseline	Low risk	Demographic and clinical characteristics are similar between groups.
Co‐interventions	Low risk	The trial author was contacted and reported that there were no co‐interventions.
Compliance	Low risk	All participants were seen for three physical therapy visits
Timing of outcome assessment	Low risk	Both groups were measured at same time
Other bias	Low risk	Free of other sources of bias