Parke 1995.

Study characteristics
Methods	Study design: parallel‐group randomized controlled trial Sample size: 77 Country: USA Setting: secondary care hospital Dates conducted: not reported Postoperative opioid used and delivery: morphine PCA Pain score collection: blinded investigator Concurrent postoperative analgesics: none reported
Participants	Inclusion criteria Abdominal or vaginal hysterectomy ASA 1 or 2 Aged 25‐80 years old Exclusion criteria Upper gastrointestinal bleed Renal disease Intolerance to NSAIDS Asthma Psychiatric disease Malignancy
Interventions	Group Pre‐emptive (37 participants): 30 mg ketorolac 30 minutes before incision and saline placebo at skin closure (both 1 mL) Group Postsurgical (40 participants): saline placebo 30 minutes before incision and 30 mg ketorolac at skin closure (both 1 mL)
Outcomes	Postoperative pain (0‐100 mm VAS at 12 and 24 hours) Morphine consumption (mg at 24 hours)
Notes	Funding: not reported Declarations of interest: not reported Authors contacted: no Other: median and range converted to mean and SD for pain score data (Hozo 2005)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No mention. Quote "Patients were randomised..."
Allocation concealment (selection bias)	Unclear risk	No mention. Quote "Patients were randomised..."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Identical placebo used and both 1 mL. Quote "...placebo injection at skin closure"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded. Quote "...by an investigator who was unaware of the group to which the patient belonged"
Incomplete outcome data (attrition bias) All outcomes	High risk	High number of dropouts, more in intervention group including two who were discharged early and therefore likely to have lower pain. Quote "...were discharged before 24 hour follow up"
Selective reporting (reporting bias)	Unclear risk	No protocol or clinical trial registration
Other bias	High risk	More vaginal hysterectomies in post‐incision group which on regression analysis were associated with pain as an outcome