Lim 2005.

Study characteristics
Methods	Randomised controlled trial
Participants	Setting: recruited from KK Women's and Children's Hospital, Singapore Participants: age 30 ± 6 years (AMB) and 31 ± 5 years (BI) Sample size: N = 60 Inclusion criteria: ASA I nulliparous labouring parturients at term who requested neuraxial analgesia in established labour with cervical dilatation less than or equal to 5 cm and with baseline pain scores more than or equal to 50 (on a 0–100 visual analogue scale (VAS): 0 = no pain, 100 = worst pain imaginable)
Interventions	AMB (n = 30): 5 mL epidural boluses of levobupivacaine 0.1% with fentanyl 2 µg/mL every 30 min. This was initiated 15 min after the intrathecal component was given BI (n = 30): levobupivacaine 0.1% with fentanyl 2 µg/mL at a rate of 10 mL/h as a continuous infusion delivered by a syringe pump. The epidural infusion was initiated in the next minute after the intrathecal component was given
Outcomes	Rate of breakthrough pain with need for anaesthetic intervention Rate of caesarean delivery Rate of instrumental delivery Duration of labour Total LA/hour Maternal satisfaction Apgar scores
Notes	Study dates not stated Funding sources not declared No conflict of interests declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised using a computer‐generated table: Quote:"The parturients were randomized using a computer generated table into two groups."
Allocation concealment (selection bias)	High risk	Allocation concealment was not mentioned.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	The study was:Quote:"double‐blinded", but did not specifically state if participants and clinical personnel were blinded.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of participants were not stated. Outcome assessors were blinded: Quote:"An anesthetist, who was not involved in performing the block and blinded to the mode of drug delivery, collected the following data..."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts
Selective reporting (reporting bias)	Low risk	All a priori outcomes reported based on published protocol
Other bias	Low risk	Appears to be free of other sources of bias. Sample size calculation: sample size was computed to detect a 40% reduction of incidence of breakthrough pain