Apiliogullari 2007.

Methods	Double‐blind randomized controlled trial
Participants	Age (years, mean ± SD): Group I = 36.16 ± 10.7, Group II = 35.36 ± 9.6, Group III = 33.46 ± 10.7 Gender (M:F): Group I = 11:49, Group II = 21:39, Group III = 20:40 Inclusion criteria: ASA I or II, elective surgery Exclusion criteria: patients with difficulties in communication or with a history of allergy to diphenhydramine or amide group drugs, diabetes mellitus or cardiac problems and patients who received analgesics or sedative drugs within the 24 hours before surgery Recuitment: 180 adult patients randomly assigned (60 in each group) Setting: Turkey
Interventions	Pretreatment with venous occlusion Group I (placebo) received normal saline 2 ml, Group II received lidocaine 2 ml (40 mg) (Aritmals 2%; Biosel, Istanbul) and Group III received diphenhydramine hydrochloride 2 ml (20 mg) (Benisons; Biosel, Istanbul) A 1 min venous occlusion, followed by propofol into a cephalic forearm vein of the antecubital fossa
Outcomes	Pain intensity assessed on 3‐point scale 0 = no pain 1 = mild pain 2 = severe pain (strong vocal response accompanied by facial grimacing, arm withdrawal or tears) Outcomes reported and used Incidence of high‐intensity pain Incidence of pain Adverse effects Outcomes sought but not reported Patient satisfaction
Notes	Period of the study: dates not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	N/A
Allocation concealment (selection bias)	Unclear risk	N/A
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Identical syringes containing study drugs were prepared and labelled by a pharmacist not involved in this study."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"An independent anaesthetist, who was unaware of group assignments, assessed the intensity of the pain the patients experienced."
Incomplete outcome data (attrition bias) All outcomes	Low risk	N/A but assuming from the table all patients were included
Selective reporting (reporting bias)	Unclear risk	N/A
Other bias	Low risk	The study appears to be free of other sources of bias