Andrade 2008.

Methods	RCT
Participants	57 participants. 1. Back School group n = 29. 2. Waiting‐list group n = 28. Inclusion criteria: non‐specific chronic low back pain for over 3 months, pain present during the study, and cognitive ability to sign the consent form. Exclusion criteria: pregnancy, disc herniation, infectious or inflammatory spondylitis, tumours, fractures, thoracic, shoulder, or neck pain, and fibromyalgia.
Interventions	1. Back School group: 4 sessions x 60 minutes in 4 weeks. Information on anatomy, causes of LBP, ergonomics, exercises, and advice on physical activity. 2. Waiting‐list group.
Outcomes	1. Pain: visual analogue scale. 2. Disability: Roland‐Morris Disability Questionnaire.
Notes	Secondary care setting. Funding: N/A.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomised using a system developed in Visual Basic into 2 groups: experimental (34 participants) and control (36 participants).
Allocation concealment (selection bias)	Unclear risk	The sequence generation procedure or the method of allocation were not mentioned. The title, abstract, and flowchart indicate that it is an RCT.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No mention of any attempts to blind the participants
Blinding (performance bias and detection bias) All outcomes	High risk	No mention of any attempts to blind the care providers
Blinding of outcome assessment (detection bias) All outcomes	Low risk	All participants were evaluated by the same examiner, who was blind to group allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The percentage of withdrawals and dropouts was within the acceptable rate (less than 20%).
Intention‐to‐treat Analysis	Unclear risk	No information about intention‐to‐treat analysis
Selective reporting (reporting bias)	Unclear risk	It was unclear if the published report included all expected outcomes.
Similarity of baseline characteristics?	Low risk	Table I presents the data at baseline of the experimental and control groups, with no statistically significant difference between groups.
Co‐interventions avoided or similar?	Unclear risk	Not mentioned
Compliance acceptable?	Low risk	Compliance was acceptable based on the reported intensity/dosage, duration, number, and frequency for both the intervention and control groups.
Timing outcome assessments similar?	Low risk	All important outcomes assessments for both groups were measured at the same time.