Forget 2019.

Study characteristics
Methods	Belgian, multicenter, prospective, double‐blind, placebo‐controlled, parallel assignment, randomized phase III trial in high‐risk breast cancer patients
Participants	NSAID n = 96, age 56.1 ± 14 Type of breast surgery: mastectomy (n = 60), breast‐conserving surgery (n = 34), missing data (n = 2) Placebo n = 107, age 55.4 ± 13.9 Type of breast surgery: mastectomy (n = 59), breast‐conserving surgery (n = 48)
Interventions	NSAID versus placebo Experimental: ketorolac Ketorolac 30 mg IV (single dose) at induction of anesthesia (pre‐incision) Placebo comparator: control Saline 3 mL IV (single dose) at induction of anesthesia (pre‐incision)
Outcomes	Postoperative pain intensity 24 hours after surgery Verbal simple scale: VAS 3.33 ± 2.2 versus 3.75 ± 2.3 Bleeding from any location within 90 days: 1 versus 0 participants Need for blood transfusion: 0 versus 0 participants Other side effects of NSAID use: 8 versus 7 participants Length of hospital stay: 3.9 ± 1.2 days versus 3.7±1 days
Notes	Funded by the Anticancer Fund, the Belgian Society of Anaesthesia and Resuscitation, the Foundation Saint‐Luc; the Commission du Patrimoine of the Université catholique de Louvan, St‐Luc Hospital
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomized controlled trial. Randomization of eligible patients was done the day before surgery and used randomisation blocks of 4. There was no stratification factor.
Allocation concealment (selection bias)	Low risk	In each center, a randomisation list was kept accessible exclusively to the pharmacist in charge of the preparation of the study product (ketorolac or placebo). For each patient, a sealed opaque envelope was provided.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Patients were given one dose of intervention or a matching placebo. Each patient was randomly assigned on a 1:1 ratio to receive either 30 mg of ketorolac or a placebo during the induction of anesthesia (pre‐incision). The placebo consisted of NaCl 0.9% (3 mL) and was identically presented to ensure double‐blinding. No dose modification was allowed because only one single dose was administered.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	A randomisation list was kept accessible exclusively to the pharmacist in charge of the preparation of the study product.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	1 patient with missing data in placebo group for postoperative pain intensity within 24 (± 12) hours of surgery
Selective reporting (reporting bias)	Low risk	Trial registration confirmed all reported outcomes were assessed