Background:Osteoarthritis of the hip and knee is one of the most common causes of reduced mobility. It also causes stiffness and pain. Opioids can offer pain relief but is usually used for severe acute pain caused by major trauma or surgery. The use of opioids for relief of chronic pain caused by arthritis has increased over the last few decades.[1]Objectives:This study aims to investigate the use of strong opiates for patients with hip and knee osteoarthritis before and after joint replacement surgery, over a 13 years period in New Zealand.Methods:This study included patients with osteoarthritis who underwent publicly funded primary hip and knee replacement surgeries in 2005-2017 in New Zealand. These records were identified from the National Minimum Dataset (NMD). They were cross referenced with the NZJR data to exclude the admissions not for primary hip or knee replacement surgeries. Patients without a diagnosis of osteoarthritis were excluded.The PHARMS dataset was linked to the NMD to identify the use of strong opiates before and after surgeries. The strong opiates available for community dispensing in New Zealand and included in this study are: dihydrocodeine, fentanyl, methadone, morphine, oxycodone and pethidine. Use of opiate within three months prior to surgery and within 12 months post-surgery were examined by gender, age group, ethnicity, Charlson Comorbidity Index score and year of surgery. Differences by subgroup was examined with Chi- square test. Logistic regression model was used to calculate the adjusted odds ratios of strong opiate use before and after surgery compared with no opiate use.Results:We identified 53,439 primary hip replacements and 50,072 primary knee replacements with a diagnosis of osteoarthritis. Of patients with hip osteoarthritis, 6,251 (11.7%) had strong opiate before hip replacement surgeries and 11,939 (22.3%) had opiate after surgeries. Of patients with knee osteoarthritis, 2,922 (5.8%) had strong opiate before knee replacement surgeries and 15,252 (30.5%) had opiate after surgeries.The probability of patients with hip and knee osteoarthritis having opiate decreased with age, increased with Charlson comorbidity index score, and increased over time both before and after surgeries. Male patients with hip and knee osteoarthritis were less likely to have opiate than female patients both before and after surgeries. New Zealand Europeans with hip and knee osteoarthritis were more likely to receive opiate than other ethnic groups prior to surgeries, but were less likely to have opiate than Asians post-surgeries.Patients who had opiate before surgeries were more likely to have opiate after surgeries than those who did not have opiate before surgeries. The odds ratio was 8.34 (95% confidence interval (CI): 7.87-8.84) for hip osteoarthritis and 11.94 (95% CI: 10.84-13.16) for knee osteoarthritis after adjustment for age, gender, ethnicity, year of surgery and Charlson comorbidity index score. Having opiate prior to surgeries also increased the probability of having opiate for 6 weeks or more after surgeries substantially. The adjusted odds ratio was 21.46 (95% CI: 19.74-23.31) for hip osteoarthritis and 27.22 (95% CI: 24.95-29.68) for knee osteoarthritis.Conclusion:Preoperative opiate holidays should be encouraged. Multiple strategies need to be used to develop analgesic plans that allow adequate rehabilitation, without precipitating a chronic opiate dependence. Clinicians would also benefit from clear guidelines for prescribing strong opiates.References:[1] Nguyen, L.C., D.C. Sing, and K.J. Bozic,Preoperative Reduction of Opioid Use Before Total Joint Arthroplasty.J Arthroplasty, 2016.31(9 Suppl): p. 282-7.Disclosure of Interests:None declared
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