Early postoperative opioid consumption: mediator, marker, or consequence? Reconsidering causal interpretation

We read with interest the study by Ervin-Sikhondze et al, which reports an independent association between opioid consumption within the first 30 postoperative days and new persistent opioid use (NPOU).1 The integration of patient-reported consumption with prescription monitoring data represents a methodological strength. However, the causal interpretation of this association requires further clarification.