Kumar 2004.

Methods	RCT Approved by the ethics committee and written informed consent obtained Setting: India Funding: unspecified
Participants	48 ASA 1 or 2 patients aged between 20 and 70 years undergoing major abdominal surgery
Interventions	Treatment group: TEA (T12‐L1 with the catheter advanced 3 cm passed the needle tip) with bupivacaine 0.25% started after the end of surgery (n = 16) Control group: TEA with morphine 0.02 mg/mL (n = 16) General anaesthesia for all participants
Outcomes	VAS (visual analogue) scores at 22 (taken as 24 hours) and 40 (taken as 48 hours) (taken as at rest)
Notes	One group with a combination of bupivacaine and morphine ‐ not retained Duration of treatment unspecified ‐ taken as 48 hours (i.e. equivalent to measurements)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"at random", no details
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"double‐blind"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"double‐blind"
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Unclear risk	Type of surgery not mentioned Unilateral sensory impairment and motor weakness in 3/16 participants, retained in their group