Summary of findings for the main comparison. Thoracic epidural anaesthesia versus conventional pain control to prevent persistent pain after open thoracotomy.

Should thoracic epidural anaesthesia or conventional pain control be used to prevent persistent pain after open thoracotomy
Patient or population: people undergoing open thoracotomy Settings: university and teaching hospitals in China, Turkey and Canada Intervention: thoracic epidural anaesthesia Comparison: conventional pain control
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	Conventional pain control	Thoracic epidural anaesthesia
Persistent pain 3 to 18 months after thoracotomy (We defined persistent postsurgical pain as new pain that did not exist before the operation, measured using differences in scores based on validated pain scales; patient interview between 3 to 18 months after surgery.)	Study population		OR 0.52 (0.32 to 0.84)	499 (7 studies)	⊕⊕⊕⊝ moderate1,2,3	All studies investigated persistent pain after open thoracotomy. The results cannot be extended to video‐assisted thoracotomy or other (minimally invasive) surgeries of the chest. The five of the seven included studies using thoracic epidural anaesthesia showed the strongest effect. The results cannot be extended to other interventions like paravertebral blocks. Conventional pain control with opioids and NSAID was the comparator. Event rates of persistent pain after thoracotomy were reported between 25% to 65% Regional anaesthesia may prevent persistent (chronic) pain after open thoracotomy in one out of seven people treated, thoracic epidural anaesthesia in one out of five people treated.
	525 per 1000	332 per 1000 (230 to 453)
	Low
	250 per 1000	130 per 1000 (83 to 200)
	Moderate
	500 per 1000	310 per 1000 (213 to 429)
Adverse effects of epidural anaesthesia ‐ not reported	See comment	See comment	Not estimable	‐	See comment	Adverse effects of epidural anaesthesia were not systematically reported and due to their low frequency are better investigated in patient registries.
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; NSAID: nonsteroidal anti‐inflammatory drugs; OR: odds ratio
GRADE Working Group grades of evidence High quality: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate quality: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of effect, but there is a possibility that it is substantially different. Low quality: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of effect, but there is a possibility that it is substantially different. Very low quality: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.

¹While outcome observers' blinding was described, study participants were not blinded; this is acceptable because participant and provider blinding is difficult in regional anaesthesia.
 ²We downgraded quality of evidence by one level because none of the studies performed an intention‐to‐treat analysis. Considerable attrition might have led to bias.
 ³There was no evidence of statistical heterogeneity. Studies that failed to improve immediate postoperative pain control had lower effect estimates beyond three months (null bias).