Gillan 1998.

Study characteristics
Methods	Study design: randomized controlled trial Setting: Abeerden Royal Hospitals Trust, Aberdeen, UK
Participants	Acute/subacute population Inclusion criteria: patients with an subacute episode of LBP (< 12 weeks duration) and a lateral shift of the lumbosacral spine Exclusion criteria: patients with chronic back pain or previous spinal surgery and those who needed immediate surgical intervention N = 40: treatment group = 19; control group = 21 Age range, years: treatment group = 29‐55 (male), 26‐53 (female); control group = 29‐58 (male), 32 to 53 (female) Sex (N): treatment group = 7 female, 4 male; control group = 6 female, 8 male
Interventions	Treatment group: McKenzie method Control group: non‐specific back massage and standard back care advice Both groups were treated by the same therapist using a standard protocol and attended 2 or 3 times during the first week and thereafter at the discretion of the therapist.
Outcomes	Disability (ODI) Timing of assessments: 4 weeks and 3 months
Notes	Patients were treated by a physiotherapist holding the McKenzie diploma in mechanical diagnosis and therapy
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Patients were randomly allocated, using a list of random numbers, to one of two groups for management".
Allocation concealment (selection bias)	High risk	A list of random numbers was 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	High risk	High and not balanced rate of withdrawals for short‐term follow‐up (30% in control group; 40% in McKenzie group, approximately)
Intention to treat analysis	High risk	Patients who withdrawn from the study were excluded from the analysis.
Selective reporting (reporting bias)	Unclear risk	Protocol not available and the report does not include enough information to make this judgement.
Group similarity at baseline	Low risk	There were no important differences among the groups in baseline demographic characteristics or outcome measures.
Co‐interventions	Unclear risk	No information on the text. We attempted to contact the authors, but our attempts were unsuccessful.
Compliance	Low risk	Both groups were attended 2 to 3 sessions during the first week and thereafter at the description of the therapist.
Timing of outcome assessment	Low risk	Patients in both groups were evaluated at same time
Other bias	Low risk	Free of other sources of bias