Besic 2014.

Methods	Double‐blinded (patient/outcome assessor), RCT Sequence generation by a computer‐based, random numbers generator Follow‐up: 3 months
Participants	Participants: 120 women in a hospital setting in Ljubljana, Slovenia Operation: axillary lymphadenectomy and breast reconstruction Groups, size: 60/60 Age (lymphadenectomy, reconstruction): 60, 48 All female participants Comorbidities: none
Interventions	Group 1 (levobupivacaine): intraop: before wound closure, a fenestrated wound catheter was placed under the pectoralis major muscle and upon the entire 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): intraop: continuous intravenous infusion with piritramide (30 mg), metoclopramide (20 mg) and metamizole (2.5 g) in 100 mL of 0.9% sodium chloride (3 mL/h‐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 No adverse events reported
Notes	Study characteristics and data combined with Strazisar 2014. Axillary lymphadenectomy and breast reconstruction performed on 60 participants per procedure. Results from both procedures were combined to best represent pain outcomes. Funding sources: financial support was not described. Conflicts of interest: no conflict of interest statement was provided.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "the research nurse performed randomization 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: "a smaller portion of patients treated with local anesthetics had chronic pain in comparison to the control group." "Chronic pain three months after operation is less frequent in the test group."