Lenz 2008.

Methods	Study design: parallel‐group randomized controlled trial Sample size: 100 Country: Norway Setting: secondary care hospital Dates conducted: not reported Postoperative opioid used and delivery: PCA fentanyl (first 4 hours) then oxycodone 5 mg after Pain score collection: not reported Concurrent postoperative analgesics: paracetamol 2 g pre‐medication then paracetamol 1 g and diclofenac 50 mg 6 hours after pre‐medication, evening, and next morning
Participants	Inclusion criteria Adults (18 to 70 years) Scheduled for endoscopic reconstruction of the anterior cruciate ligament ASA 1 or 2 Exclusion criteria Regular use of paracetamol, NSAIDs, corticosteroids, antiemetics, or opioids Contraindications for NSAIDs Obesity Pregnancy
Interventions	Group Pre (50 participants): 1.5 mcg/kg IV fentanyl before remifentanil infusion (at induction) and 10 minutes before the end of surgery (3 mcg/kg in total) Group Post (50 participants): saline placebo at induction and 3 mcg/kg IV fentanyl 10 minutes before the end of surgery
Outcomes	Opioid consumption (mcg fentanyl 0 to 4 hours then mg oxycodone 4 to 24 hours) Postoperative pain (0‐to‐4 VRS at 1, 2, 3, and 4 hours after surgery) Nausea and vomiting (yes/no, both 0 to 4 hours and 4 to 24 hours)
Notes	Funding: departmental funding Declarations of interest: 2 authors received compensation for lectures from GlaxoSmithKline. Authors contacted: we contacted authors for further information and received a response, however no further data were available. Other: opioid consumption data extracted from graph using computer software. Pain reported as median so included in narrative synthesis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated codes. Quote: "randomization was based on computer‐generated codes"
Allocation concealment (selection bias)	Low risk	Quote: "stored in sequentially numbered, sealed envelopes. A nurse not participating in the handling or the evaluation of the participant was responsible for opening the envelopes and preparing the two coded syringes"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Group Pre, both syringes contained fentanyl 1.5 mg/kg for participant’s weight. In Group Post, syringe no. 1 contained 0.9% saline (placebo) and syringe no. 2 contained fentanyl 3.0 mg/kg based on participant’s weight. Saline was used for dilution so that the syringes contained the same volume for participants with the same weight"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Likely blinded based on above information
Incomplete outcome data (attrition bias) All outcomes	Low risk	Exclusions unlikely to cause bias. Quote: "from 112 participants, 12 were excluded because the surgical procedure did not proceed to repair as planned"
Selective reporting (reporting bias)	Low risk	NCT00241332. Primary outcomes pre‐stated. Quote: "the study was reported to ClinicalTrials.gov ID: NCT00241332"
Other bias	Low risk	Similar groups and no industry funding. Quote: "the demographic characteristics of these 100 patients were similar in the two groups"