Strazisar 2014.

Methods	Doubl‐ 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: radical mastectomy and breast reconstruction Groups, size: 30/30 Age (range, 1, 2): 25‐64, 47.6, 48.0 All female participants Comorbidities: smoking, groups 1, 2 (9, 10); depression, groups 1, 2 (3, 1) Remarks: ASA I, II, and III
Interventions	Group 1 (levobupivacaine): intra‐op: 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): 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 were measured. Adverse events: 2 participants (1, 1) underwent additional surgical procedures due to haematoma, 4 participants (1, 3) experienced inflammation postoperatively, and unilateral lymphoedema of the arm was present in 2 participants (1, 1)
Notes	Funding sources: "study was entirely financed by the Institute of Oncology as a part of public service." Conflicts of interest: "the authors declare that they have no competing interests."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomization was made by 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	Unclear risk	Participants were blinded, but no description of medical staff's knowledge other than, quote: "after randomization... the principal investigator was informed about the treatment allocation of the patient."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "data about pain were collected by nursing staff, that is, by an independent observer."
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: "in the test and the control groups of patients, pain was reported in 16.7% (5/30) and 50% (15/30), respectively." "We observed that patients treated with a LA experienced a lower frequency of chronic pain compared to patients treated with standard analgesic."