Strazisar 2012.

Methods	Double‐blinded (participant/outcome assessor), randomized clinical trial Sequence generation by a computer‐based, random numbers generator Follow‐up: 3 months
Participants	Participants: 60 women in a hospital setting in Ljubljana, Slovenia Operation: breast cancer surgery with axillary lymphadenectomy Groups, size: 30/30 Age (all, 1, 2): 60 (30‐84), 57.4, 62.9 All female participants Comorbidities: diabetes, groups 1, 2 (4, 8); depression, groups 1, 2 (1, 4) Remarks: ASA I, II, and III
Interventions	Group 1 (levobupivacaine): intra‐op: before wound closure, a fenestrated wound catheter was placed near the axillary vein and upon the whole length over the upper side of the wound. The wound catheter was fenestrated along 15 cm in the distal part. A bolus of 15 mL of 0.25% levobupivacaine was injected into the wound through the catheter immediately after wound closure. Surgical drains and the fenestrated catheter were clamped for 5 min to enable bolus absorption. Elastomeric pump was connected containing 100 mL of 0.25% levobupivacaine. Infusion at 2 mL/h was continuous for 50 h Group 2 (piritramide): intra‐op: continuous IV infusion with piritramide (30 mg), metoclopramide (20 mg) and metamizole (2.5 g) in 100 mL of 0.9% sodium chloride (3 mL/h to 6 mL/h) until 24 h postoperatively Adjuvants: none Immediate post‐op pain control: significantly improved, significantly reduced analgesic consumption
Outcomes	Continuous: none Dichotomus: overall pain/no pain at 3 months Other reported: nausea, opioid consumption, and length of hospital stay and were measured Adverse events: 3 participants (2, 1) underwent additional surgical procedures due to haematoma and 9 participants (5, 4) experienced inflammation postoperatively
Notes	Funding sources: no funding source given Conflicts of interest: "no potential conflicts of interest were disclosed."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization was performed using random numbers generated by a computer
Allocation concealment (selection bias)	Low risk	Quote: "randomization and numbers were placed in sealed opaque envelopes to ensure concealment of allocation at enrollment."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "participants were randomly grouped."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "clinicians who recorded data about chronic pain were blinded about randomisation group of patients."
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants completed the follow‐up evaluation.
Selective reporting (reporting bias)	Low risk	No subgroup analysis or selective reporting was noted.
Null bias	Low risk	Quote: "pain (at 3 months) was reported by 17% and 50% of patients." Continuous infusion of local anesthetic reduced pain compared to control.