Tesio 1993.

Methods	RCT, participants allocated at random (method of randomization not described).
Participants	44 participants (25 males, 19 females, aged 23‐63 years), referred from an outpatient service of a rehabilitation unit in a large teaching hospital. Inclusion criteria: LBP with or without radiation, duration > 1 month, herniation or protrusion, failure of 1 or more conservative approaches. Exclusion criteria: neoplastic, inflammatory or metabolic causes of back pain, or indication for urgent surgery.
Interventions	Traction: T1) Intermittent auto‐traction, participant provides traction force by pulling vigorously on the bar at the head of the table for a period of 3‐6 sec, 1 min rest, 30‐60 min session, every 2nd or 3rd day, total 3‐10 sessions. If the participant reported benefit, the treatment was continued for 3‐6 more sessions until no further improvement. T2) Passive traction. Traction force was adjusted approximately every 10 min, 35% of body weight, 45 min, daily bases for 5‐10 sessions.
Outcomes	Immediate outcomes (improved): T1) 17 of 22 participants, T2) 4 of 22 participants (statistically significant). Cross‐over: non‐responders to either treatment were crossed over to the other modality after a delay of 4‐5 days.
Notes	Most results given for only auto‐traction responses (they openly favoured the treatment of the researchers).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No mention of randomization procedure.
Allocation concealment (selection bias)	Unclear risk	No information provided on allocation concealment.
Blinding (performance bias and detection bias) All outcomes ‐ participants	Low risk	No mention of attempts to blind the participants. It is likely that the participants were blinded.
Blinding (performance bias and detection bias) All outcomes ‐ providers	High risk	No mention of attempts to blind the care providers. It is unlikely that the care providers were blinded.
Blinding (performance bias and detection bias) All outcomes ‐ outcome assessors	Unclear risk	No mention of attempts to blind the outcome assessors.
Incomplete outcome data (attrition bias) All outcomes ‐ loss to follow‐up	Unclear risk	It is not clear how many participants were lost to follow‐up.
Incomplete outcome data (attrition bias) All outcomes ‐ intention to treat analysis	High risk	No intention‐to‐treat analysis was used.
Selective reporting (reporting bias)	Low risk	Published results included all prespecified outcomes.
Group similarity at baseline (selection bias)	Low risk	No significant differences were found between groups with respect to sex, age, pain duration and score, presence of positive straight leg raise test or neural deficits, presence of more than 1 disc affected, presence of spinal stenosis, history of previous episodes and possible psychological bias.
Influence of co‐interventions (performance bias)	High risk	Co‐interventions were allowed.
Compliance with interventions (performance bias)	Unclear risk	Not mentioned.
Timing of outcome assessments (detection bias)	High risk	All important outcome assessments for all intervention groups were not measured at the same time. The auto‐traction group was evaluated after 3 sessions, whereas the passive traction group was assessed after 5 treatment sessions.