Opioid analgesic effects on subjective well‐being in the operating theatre*

Abstract

SummaryExposure to opioid analgesics due to surgery increases the risk of new persistent opioid use. A mechanistic hypothesis for opioids' abuse liability rests on the belief that, in addition to pain relief, acute opioid treatment improves well‐being (e.g. via euphoria) and relieves anxiety. However, opioids do not consistently improve mood in laboratory studies of healthy non‐opioid users. This observational study determined how two commonly used opioid analgesics affected patients' subjective well‐being in standard clinical practice. Day surgery patients rated how good and how anxious they felt before and after an open‐label infusion of remifentanil (n = 159) or oxycodone (n = 110) in the operating theatre before general anaesthesia. One minute after drug injection, patients reported feeling intoxicated (> 6/10 points). Anxiety was reduced after opioids, but this anxiolytic effect was modest (remifentanil Cohen's d = 0.21; oxycodone d = 0.31). There was moderate to strong evidence against a concurrent improvement in well‐being (Bayes factors > 6). After remifentanil, ratings of ‘feeling good’ were significantly reduced from pre‐drug ratings (d = 0.28). After oxycodone, one in three participants felt better than pre‐drug. Exploratory ordered logistic regressions revealed a link between previous opioid exposure and opioid effects on well‐being, as only 14 of the 80 opioid‐naïve patients reported feeling better after opioid injection. The odds of improved well‐being ratings after opioids were higher in patients with previous opioid exposure and highest in patients with > 2 weeks previous opioid use (adjusted OR = 4.4). These data suggest that opioid‐induced improvement of well‐being is infrequent in opioid‐naïve patients. We speculate that peri‐operative exposure could increase risk of persistent use by rendering subsequent positive opioid effects on well‐being more likely.