Abstract
Robust evidence on the effectiveness of peri-operative local anaesthetic infiltration (LAI) is required before it is incorporated into the pain management regimen for patients receiving total hip replacement (THR). We assessed the effectiveness of LAI using a systematic review and a fully powered randomised controlled trial (RCT) with economic evaluation.
We searched MEDLINE, Embase and Cochrane databases for RCTs of peri-operative LAI in patients receiving THR. Two reviewers screened abstracts, extracted data, and liaised with authors. Outcomes were pain, opioid use, mobilisation, hospital stay and complications. If feasible, we conducted meta-analysis.
In the APEX RCT, we randomised 322 patients awaiting THR to receive additional peri-operative LAI (60mls 0.25% bupivacaine plus adrenaline) or standard anaesthesia alone. Post-operatively, all patients received patient-controlled morphine. The primary outcome was joint pain severity (WOMAC-Pain) at 12 months. Patients and outcome assessors were blinded to allocation.
Within APEX, cost-effectiveness was assessed from the health and social-care perspective in relation to quality adjusted life years (QALYs) and WOMAC-Pain at 12-months. Resource use was collected from hospital records and patient questionnaires.
In the systematic review, we identified 13 studies (909 patients). Patients undergoing THR receiving LAI experienced greater pain reduction at 24 hours at rest, standardised mean difference (SMD) −0.61 (95%CI −1.05, −0.16; p=0.008) and at 48 hours during activity, SMD −0.43 (95%CI −0.78, −0.09; p=0.014). Patients receiving LAI spent fewer days in hospital, used less opioids and mobilised earlier. Complications were similar between groups. Long-term outcomes were not a focus of these studies.
In the APEX RCT, pain levels in hospital were broadly similar between groups, probably due to patient-controlled analgesia. Opioid use was similar between groups. Time to mobilisation and discharge were largely dependent on local protocols and did not differ between groups. Patients receiving LAI were less likely to report severe pain at 12 months than those receiving standard care, odds ratio 10.2 (95%CI 2.1, 49.6; p=0.004). Complications were similar between groups.
In the economic evaluation, LAI was associated with lower costs and greater cost-effectiveness than standard care. Using a £20,000 per QALY threshold, the incremental net monetary benefit was £1,125 (95%CI £183, £2,067) and the probability of being cost-effective was greater than 98 %.
The evidence suggests that peri-operative LAI is a cost-effective intervention for reducing acute and chronic post-surgical pain after THR.
