Opioid use after surgical treatment in the Danish population-Protocol for a register-based cohort study.

Background: Over the past 25 years, global opioid consumption has increased. Denmark ranks fifth in opioid use globally, exceeding other Scandinavian countries. Postsurgical pain is a common reason for opioid prescriptions, but opioid use patterns after patient discharge from the hospital are unclear. This study examines trends in opioid prescription among Danish surgical patients over a year.

Methods: This register-based cohort study will use data from Danish governmental databases related to patients undergoing the 10 most frequent surgical procedures in 2018, excluding cancer-related and minor procedures. The primary outcome will be the dispensed postoperative opioid prescriptions at retail pharmacies over four quarters. Secondary analyses will include associations with sex, age, education attainment, and oral morphine equivalent quotient. Surgical treatments and diagnoses will be identified using NOMESCO procedure codes and ICD-10 codes. Opioids will be identified by ATC codes N02A and R05DA04. Subjects will be classified as preoperative opioid consumers or non-opioid consumers based on opioid prescriptions redeemed in the 6 months before surgery.

Discussion: The study will use extensive national register-based data, ensuring consistent data collection and enhancing the generalizability of the findings to similar healthcare systems. The study may identify high-risk populations for long-term opioids and provide information to support opioid prescribing guidelines and public health policies.