Brown 2004

Methods	Triple‐blinded (participant, provider, outcome assessor) clinical RCT Sequence via computer‐generated list Follow‐up: 3 months
Participants	Participants: 100 men at university hospital in Minnesota, USA Operation: elective radical retropubic prostatectomy 2 groups, size: 50/49 (completed) Age ± SD (group 1, 2): 61.0 (± 7.5), 61.6 (± 7.0) All male participants Exclusion criteria: age < 35 or > 85
Interventions	Group 1 (control): after sedation, lumbar region injected with 1% lidocaine SC in one of lumbar interspaces between 2nd‐5th vertebral bodies. SC injection of sterile saline instead of intrathecal injection into subarachnoid space. Received IV fentanyl citrate bolus (4 µg/kg) immediately after induction, followed by continuous infusion (2 µg/kg/h) until fascial closure. Group 2 (active intrathecal block): after sedation, lumbar region injected with 1% lidocaine SC in one of lumbar interspaces between 2nd‐5th vertebral bodies. Mixture of bupivacaine (15 mg isobaric, 0.75%), clonidine (75 µg), morphine (0.2 mg) injected into subarachnoid space. No intraoperative fentanyl in this group, rather equal volume of saline as a bolus and infusion. Both groups had sedation with IV fentanyl and midazolam. Standardized GA with sodium thiopental, succinylcholine, cisatracurium, isoflurane and nitrous oxide in O2. When study drug infusion discontinued, IV ketoralac 30 mg to both groups. Phenylephrine and ephedrine were used as needed to maintain an adequate blood pressure. In PACU, both groups treated with morphine (1 mg to 2 mg IV every 10 min as needed), droperidol for nausea, then naloxone if persisted diphenhydramine for pruritus initially then naloxone infusion if persisted. Once on the floor, postoperative pain management with scheduled Ketoralac (15 mg IV every 6 h x 6 doses), PCA morphine (1 mg bolus, 10‐min lockout, no basal infusion) for 24 h then oral paracetamol/codeine (650/30 mg) every 6 h as needed. Adjuvants: clonidine Immediate post‐op pain control: significantly improved, significantly reduced analgesic consumption
Outcomes	Dichotomous: pain/no pain at 3 months Continuous: numerical pain scale, SF‐36 at 3 months Other reported: none
Notes	Funding sources: not reported Conflicts of interest: no conflict of interest statement was provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomly assigned by a "computer‐generated list that made assignments based on enrolment number"
Allocation concealment (selection bias)	Low risk	Quote: "assigned to a treatment group using a sealed envelope"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "patients and providers were masked to treatment assignments...To maximize masking of the study, a consulting anaesthesiologist familiar with the study but not responsible for the intraoperative care of the patient performed the regional procedure. During this time, the anaesthesiologist for the clinical conduct of anaesthesia left the operating room...the anaesthesia team was blinded to the identity of the bolus and infusion"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "patients and providers were masked to treatment groups"
Incomplete outcome data (attrition bias) All outcomes	Low risk	One participant assigned to active block group had severe bradycardia after induction and surgery was cancelled. 3 participants in control group, 2 in active block group could not be reached at 12 weeks. Balanced numbers, low attrition rate, low risk of bias
Selective reporting (reporting bias)	Low risk	Primary outcomes fully reported on
Null bias	Low risk	Quote: "iIntrathecal analgesia improved current, least, and worst pain scores on the day of surgery and current and worst pain scores at 06:00 h the next day."