Fletcher 1995.

Study characteristics
Methods	Study design: parallel‐group randomized controlled trial Sample size: 40 Country: France Setting: secondary care Dates conducted: not reported Postoperative opioid used and delivery: IV bolus then PCA morphine Pain score collection: blinded investigator Concurrent postoperative analgesics: none reported
Participants	Inclusion criteria ASA 1 or 2 Elective total hip replacement Exclusion criteria Contraindications to NSAIDs Aged younger than 18 years or older than 85 years ASA > 3 Any type of surgery other than THR Regional anaesthesia Any condition precluding the limitation of intraoperative fentanyl administration Contraindications to the self‐administration of opioids Past history of drug abuse Severe respiratory insufficiency Long duration of surgery (more than 4 hours) Cumulative intraoperative dose of fentanyl higher than 4 mcg/kg A second operation within 48 hours Severe respiratory depression after surgery or administration of naloxone Difficulty in using the PCA device Use of analgesic drugs other than morphine
Interventions	Group PRE (20 participants): 60 mg IV ketorolac before induction and then 2 mL IV normal saline at the end of surgery Group POST (20 participants): 2 mL IV normal saline before induction and then 60 mg IV ketorolac at the end of surgery
Outcomes	Morphine consumption (mg consumed every 12 hours for 48 hours) Postoperative pain at rest and on movement (0‐10 cm VAS in the recovery room and at 1, 2, 3, 4, 5, 6 hours and every 6 hours for 48 hours) Adverse events (nausea and vomiting, pruritus, urinary retention, blood loss, number of transfusions, sedation, respiratory depression during study follow‐up)
Notes	Funding: not reported Declarations of interest: not reported Authors contacted: no Other: some pain score and morphine consumption data extracted from graph
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number table. Quote: "a random‐number table was used to generate a randomized schedule specifying the group to which each patient would be assigned upon entry into the trial".
Allocation concealment (selection bias)	Unclear risk	No mention
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐dummy placebo. Identical in appearance. Quote: "The pre‐operative KET group (PRE; n = 20) received 60 mg of KET and then 2 ml of NS".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded. Quote: "all patients and personnel involved in patient management and data collection were unaware of the group to which the patient had been assigned".
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants analysed
Selective reporting (reporting bias)	High risk	Some adverse events not reported
Other bias	High risk	More females in POST group (Gerbershagen 2014)