Predictors of Prolonged Opioid Utilization in Geriatric Patients Undergoing Spinal Operations for Degenerative Spine Disease
Anthony Nguyen
University of Texas Medical Branch
Introduction: The opioid epidemic continues to worsen: the CDC reports that over 49,000 Americans died from opioid-related toxicity in 2017, up from 30,000 deaths in 2015. Degenerative spine disease (DSD), a cause of chronic pain, affects 90% of people over the age of 50. In older individuals, disease progression may be advanced and there is an increased risk of persistent symptoms following surgery. There are currently limited studies investigating opioid utilization by geriatric patients undergoing spinal surgery. We aimed to investigate patterns of opioid utilization following spinal surgery for DSD. Methods: In this retrospective cohort study of a 5% national sample of Medicare Part A, B, and D, patients aged 66+ years who underwent an anterior cervical discectomy and fusion (ACDF), posterior cervical fusion (PCF), lumbar microdiscectomy, lumbar laminectomy, or posterior lumbar fusion for DSD-related diagnoses between 2008 and 2014 were analyzed by cox proportional hazards regression for a year after surgery. Only patients with at least 13 months of continuous Medicare Part A, B, and D coverage prior to surgery were analyzed. The primary outcome of interest was the rate of continued opioid utilization for one year following surgery, stratified by pre-operative opioid use. Other covariates in the model included demographics, geographic location, type of surgery, prior diagnoses and comorbidities, year of surgery, and Medicaid dual eligibility. Patients were censored from analysis if they died, lost coverage, enrolled in a health maintenance organization, or experienced trauma. Continuous opioid utilization was deemed related to the surgery only if a prescription was filled within 30 days of the previous prescription’s intended supply duration ending, or within 30 days of the surgery. Results: There were 14,408 Medicare enrollees in the sample who met study criteria. At one year post-operatively, 7.3% (95% CI: 6.8–7.8) of all patients and 0.37% (95% CI: 0.21–0.64) of opioid-naïve patients continued to utilize opioids. Duration of pre-operative opioid use strongly correlated with continued utilization:, 0.98% (95% CI: 0.64–1.44), 2.81% (95% CI: 2.06–3.73), 6.79% (95% CI: 5.38–8.41), and 31.33% (95% CI: 29.30–33.38) of patients who utilized opioids for one, two, three, and four quarters prior to surgery, respectively, continuously utilized opioids up to one year after surgery. The hazard ratio for cessation of utilization was 0.20 (95% CI: 0.19–0.21). Conclusion: The incidence of chronic opioid use in opioid-naïve geriatric patients undergoing surgery for DSD-related diagnoses was 0.37%. Pre-operative opioid use was the strongest predictor of prolonged utilization, which may represent sub-optimal use of non-opioid alternatives, pre-existing opioid use disorders, delayed referral for surgical evaluation of DSD, or over-prescription of opioids for non-cancer pain.
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