# Comparison of total morphine milligram equivalents at hospital discharge between opioid-naive and opioid-experienced surgical patients: a single-centre retrospective cohort study

## TL;DR

Opioid-experienced patients needed significantly more opioids after surgery compared to opioid-naive patients, suggesting a need for tailored pain management strategies.

## Contribution

This study quantifies the increased opioid requirements at discharge for opioid-experienced surgical patients using a retrospective cohort analysis.

## Key findings

- Opioid-experienced patients had a 15.4 MME day−1 higher discharge opioid dose compared to opioid-naive patients.
- These patients also required 52.0 MME day−1 more via PCA and nearly doubled their preoperative opioid use.
- Each additional preoperative MME was associated with increased PCA use during hospitalization.

## Abstract

Perioperative pain management is a key concern amid the growing opioid pandemic, particularly for opioid-experienced patients. This retrospective single-centre cohort study aimed to compare morphine milligram equivalents (MME) at hospital discharge between opioid-naive and opioid-experienced adults undergoing surgery with postoperative patient-controlled analgesia (PCA). We hypothesised that opioid-experienced patients would require higher MME at discharge, and greater intraoperative remifentanil and postoperative PCA use.

We retrospectively analysed 406 patients from 2016 to 2023 who received intravenous PCA for acute postoperative pain management. Trauma and neuraxial/regional block cases were excluded; emergency non-trauma cases included. Opioid-experienced patients were defined as chronic use of opioids for ≥3 months before surgery. The primary outcome was opioid dose at discharge in MME. Secondary outcomes were total intraoperative remifentanil dose and total PCA use in MME, analysed using multiple linear regression with permutation testing.

Opioid-experienced patients had a 15.4 MME day−1 higher discharge opioid dose (95% confidence interval [CI] 7.4–23.4 MME day−1; P<0.001), received 6.7× more opioids at discharge than opioid-naive patients (63.5 vs 9.4 MME day−1; P<0.001) and nearly doubled their own preoperative use (63.5 vs 30 MME day−1). Opioid-experienced patients also required 52.0 MME day−1 more via PCA (95% CI 13.1–90.8 MME day−1; P=0.009). Each additional preoperative MME was associated with a 0.9 MME day−1 increase in PCA use during the hospitalisation (95% CI 0.2–1.6 MME day−1; P=0.017).

Preoperative opioid experience strongly predicted postoperative opioid requirements and discharge prescribing. Early identification of opioid-experienced patients and tailored multimodal strategies may improve individualised pain management. However, the retrospective single-centre design and lack of non-opioid analgesia data limit generalisability.