Preoperative physiotherapy is cost-effective for preventing pulmonary complications after major abdominal surgery: a health economic analysis of a multicentre randomised trial

Question: Is preoperative physiotherapy cost-effective in reducing postoperative pulmonary complications (PPC) and improving quality-adjusted life years (QALYs) after major abdominal surgery? Design: Cost-effectiveness analysis from the hospitals' perspective within a multicentre randomised controlled trial with concealed allocation, blinded assessors and intention-to-treat analysis. Participants: Four hundred and forty-one adults awaiting elective upper abdominal surgery attending pre-anaesthetic clinics at three public hospitals in Australia and New Zealand. Interventions: The experimental group received an information booklet and a 30-minute face-to-face session, involving respiratory education and breathing exercise training, with a physiotherapist. The control group received the information booklet only. Outcome measures: The probability of cost-effectiveness and incremental net benefits was estimated using bootstrapped incremental PPC and QALY cost-effectiveness ratios plotted on cost-effectiveness planes and associated probability curves through a range of willingness-to-pay amounts. Cost-effectiveness modelling utilised 21-day postoperative hospital cost audit data and QALYs estimated from Short Form-Six Domain health utilities and mortality to 12 months. Results: Preoperative physiotherapy had 95% probability of being cost-effective with an incremental net benefit to participating hospitals of A$4,958 (95% CI 10 to 9,197) for each PPC prevented, given that the hospitals were willing to pay $45,000 to provide the service. Cost-utility for QALY gains was less certain. Sensitivity analyses strengthened cost-effectiveness findings. Improved cost-effectiveness and QALY gains were detected when experienced physiotherapists delivered the intervention. Conclusions: Preoperative physiotherapy aimed at preventing PPCs was highly likely to be cost-effective from the hospitals' perspective. For each PPC prevented, preoperative physiotherapy is likely to cost the hospitals less than the costs estimated to treat a PPC after surgery. Potential QALY gains require confirmation