Opiate prescription after hip and knee arthroplasty: a retrospective cohort study.

Abstract

Excessive opiate analgesia in relation to orthopaedic surgery is associated with morbidity and mortality. Pre-operative use of opiates is associated with higher post-operative use. There is little information about opiate prescribing practices in relation to elective total joint arthroplasty (TJA) in New Zealand rural centres. The aims of this study were to describe opiate use before, immediately after and 1 year after TJA, and to compare prescribing practices with local guidelines. A retrospective cohort study of elective primary hip and knee arthroplasties was conducted between January 2018 and April 2019. Opiate use was evaluated from clinical records and from electronic prescribing records and described in morphine milligram equivalents (MME) with a particular focus on pre-operative and post-operative periods, and use after 1 year. In the study period, 199 patients underwent 203 joint arthroplasties. Of these, data from 157 patients were analysed. Patient data were not analysed because of unavailable files (N=20), non-elective procedures (N=11), bilateral arthroplasties (N=4), deaths (N=4) and incomplete information (N=3). Pre-operative opiates were used by 92 (59%) patients, of whom 70 (76%) were not using opiates after 1 year. There were 126 (80%) patients who were discharged with opiate prescriptions and the vast majority, 121 (96%), did not receive discharge prescriptions that conformed to local guidelines. Despite undergoing joint arthroplasty, about one quarter of patients who had been prescribed opiates before the operation were still receiving opiates after 1 year. There was poor compliance with local guidelines.