New results suggest that patients treated with chronic opioids prior to spine surgery are “significantly less likely” to achieve meaningful improvements at one-year in pain function and quality of life; and less likely to be satisfied at one-year with higher odds of 90-day complications, regardless of dosage. The study, authored by Jeffrey M Hills (Vanderbilt University Medical Center, Nashville, USA), was presented at the 46th annual meeting of the Cervical Spine Research Society (CSRS; 6–8 December, Scottsdale, USA). The presentation was awarded the Second Place Resident/Fellow Research Award at the conference.
The investigators found that of 2,128 patients included in the study, pre-operative chronic opioid therapy was identified in 21 per cent and associated with significantly higher odds (adjusted odds ratio [95% confidence interval]) of not achieving meaningful improvements at one-year in extremity pain (aOR:1.5 [1.2-2]), axial pain (aOR:1.7 [1.4-2.2]), function (aOR:1.7 [1.4-2.2]), and quality of life (aOR:1.4 [1.2-1.9]); dissatisfaction (aOR:1.7 [1.3-2.2]); 90-day complications (aOR:2.9 [1.7-4.9]); and post-operative chronic opioid use (aOR:15 [11.4-19.7]). Their results showed that a high-pre-operative opioid dosage is only associated with post-operative chronic opioid use (aOR:4.9 [3-7.9]).
In this longitudinal cohort study, the authors aimed to determine one-year patient reported outcomes associated with pre-operative chronic opioid therapy and high-pre-operative opioid dosages in patients undergoing elective spine surgery. They defined outcomes as satisfaction, return to work, 90-day complications, and post-operative chronic opioid use.
Hills and colleagues used their state’s Prescription Drug Monitoring Program (PDMP) to collect daily Morphine Milligram Equivalents (MME) from nine-months pre-operatively until one year post-operatively. Patients included had undergone spine surgery between January 2011 and February 2017.
The authors note that patients undergoing spine surgery for degenerative spine disease at the investigators’ institution are enrolled in a longitudinal registry is they are English speaking, above the age of 18, and willing to participate. For this study, patients were excluded if they lacked one-year follow-up data, lived in a different state or had no identifiable record in the state PDMP, had pathologic spine disease (tumour or infection), or presented with less than three months of axial and/or extremity pain.
Hills and colleagues mention that back pain is the most disabling condition worldwide and over half the patients presenting for spine surgery report using opioids. They note that while pre-operative dosage has been correlated with poor outcomes, published studies have not assessed the relationship of both pre-operative chronic opioids and opioid dosage with patient reported outcomes.
According to the investigators, current literature has thus far been limited to insurance or administrative claims data, small cohorts, or self-reported opioid dosages. Lee et al, for example, collected self-reported pre-operative opioid dosages and found each 10mg increase to be associated with a corresponding decrease in patient reported outcomes at one year after surgery. Similarly, Wick et al found daily MME of 29 as a threshold for achieving Minimal Clinical Importance Difference for functional patient reported outcomes after spine surgery.
Two studies by Jain et al used commercial insurance data and reported that pre-operative chronic opioid therapy was associated with cost and increased risk of post-operative complications after spinal fusion, but they were unable to report patient reported outcomes.
The present study “addresses a gap in the literature” surrounding the association of pre-operative chronic opioid therapy and dosage with long-term patient reported outcomes after spine surgery, say the authors.
The investigators note certain limitations to their study. For example, using prescription data from their state’s PDMP required exclusion of patients living outside the state, making external validity unclear. Additionally, this method provided opioid dispensing data rather than actual opioid use. Also, while the authors chose validated instruments for pain, function, and quality of life after spine surgery, there are no well-established improvement scores for what defines clinical success.
On the importance of the study, Hills commented: “Understanding the impact of both pre-operative chronic opioid therapy and pre-operative opioid dosage on long term outcomes after spine surgery is essential to accurately inform patients and guide the development of opioid weaning protocols.”
He continued: “Given the prevalence of spine disorders and opioid use among this population, there is a need to develop effective strategies for weaning patients on chronic opioid therapy presenting for spine surgery. When considered in conjunction with the known dangers of opioids and strong evidence demonstrating no benefit to long-term opioids, our results should substantially narrow the indications for chronic opioid therapy in treating spine pathology.”