Schenk 2012.

Study characteristics
Methods	Study design: randomized controlled trial Setting: outpatient physical therapy clinics in a regional health care system, New York, USA
Participants	Acute/subacute population Inclusion criteria: at least 18 years old and experienced an episode of LBP at the time of physical therapy referral. Originally, subjects were enrolled in the study if they met at least three of five of the selection criteria in the clinical prediction rules introduced by Flynn 2002: duration of symptoms 16 days, at least one hip with 35° of internal rotation, lumbar hypomobility, no symptoms distal to the knee, and an FABQ work score 19. Exclusion criteria: history of spinal surgery; progressive disease process; being treated for psychological illness; pregnant; symptoms relative to cauda equina syndrome; did not understand English; engaged in litigation related to their LBP. Individuals who were insured through workers compensation or no fault insurance were also excluded from the study. N = 31: treatment group = 15; control group = 16 Age mean (range) years: treatment group = 39 (25‐58); control group = 46 (18‐65) Sex (N): treatment group = 12 female, 7 male; control group = 7 female, 5 male Duration of symptoms (days): treatment group = 18; control group = 15
Interventions	Treatment group: McKenzie method ‐ exercises according to the directional preference determined at the initial visit were recommended in both the clinic and as home exercises). Control group: spinal thrust manipulation ‐ treatment consisting of the regional lumbopelvic thrust technique (the therapist stood opposite the side to be manipulated. The patient was passively side‐bent away from the therapist. The therapist passively rotated the patient and then delivered a quick posterior and inferior thrust through the anterior superior iliac spine). Participants received instruction on the hand‐heel rock range of motion exercise for 30 repetitions and 20 repetitions for sessions 1 and 2, respectively. The hand‐heel rock involved lumbar movement into flexion and then extension from the quadruped position). All participants were instructed to complete a daily log of adherence to the home exercises. In addition to the STM or MDT administered in the clinic, participants performed 10 repetitions of the movements in the directional preference on an hourly basis during the day only, from session 3 until discharge as the home exercise program.
Outcomes	Pain (NRS) Disability (ODI) Timing of assessments: 4 weeks
Notes	Both groups were treated by physical therapist with certification in McKenzie method
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Participants were randomly assigned via a computerized random number generator".
Allocation concealment (selection bias)	High risk	The author was contacted and reported that the process of allocation concealment was carried out by alternating the assigned interventions.
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 percentage of withdrawals did not exceed 20% in the short term follow‐up.
Intention to treat analysis	High risk	Participants who crossed‐over were not included in the analysis.
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	Demographic and clinical characteristics were similar between groups.
Co‐interventions	Low risk	The author was contacted and reported that there were no co‐interventions.
Compliance	Low risk	"All subjects, regardless of enrolment, performed 10 repetitions of lumbar movements. Participants in the MDT group performed the repetitive movements in the DP on an hourly basis throughout the day, from session 3 until discharge as the home exercise program, a standard part of a MDT intervention. Those in the STM group performed lumbar flexion and extension in quadruped (‘cat and camel’) for 10 repetitions hourly throughout the day, from session 3 until discharge".
Timing of outcome assessment	Low risk	All participants were evaluated at the same time.
Other bias	High risk	Participants could cross‐over to the alternative at the week 2 visit if they failed to improve with the randomly assigned treatment. Participants were included if they met at least three of five of the selection criteria in clinical prediction rules. However, only those who met four of these criteria were retained for analysis.

FABQ: Fear‐Avoidance Beliefs Questionnaire
LBP: Low back pain
MDT: Mechanical Diagnosis and Therapy
NRS: Numerical Pain Rating Scale
ODI: Oswestry Disability Index
RMDQ: Roland Morris Disability Questionnaire
STM: spinal manipulative therapy
VAS: Visual Analogue Scale