Total Inpatient Morphine Milligram Equivalents Can Predict Long-term Opioid Use After Transforaminal Lumbar Interbody Fusion

Study Design. A retrospective cohort study from a single institution. Objective. The aim of this study was to assess the thresholds for postoperative opioid consumption, which are predictive of continued long-term opioid dependence. Summary of Background Data. The specific sum total of inpatient opioid consumption as a risk factor for long-term use after transforaminal lumbar interbody fusion (TLIF) has not been previously studied. Methods. Charts of patients who underwent a one, two, or three-level primary TLIF between 2014 and 2017 were reviewed. Total morphine milligram equivalents (MME) consumed was tabulated and separated into three categories based on ROC curve analysis of opioid utilization at 6-month follow-up. Multivariate binary regression analysis assessed these MME dosage categories. A further subanalysis grouped patients on the basis of whether they had used opioids preoperatively. Results. One hundred seventy-two patients met the inclusion criteria and were separated into groups who received less than 250 total inpatient MME (44%), between 250 and 500 total inpatient MME (26%), and greater than 500 total inpatient MME (27%). Patients undergoing a TLIF who received <250 total MME in the immediate postoperative period had a 3.73 (odds ratio) times smaller probability of requiring opioids at 6-month follow-up [P = 0.027, 95% confidence interval (95% CI) 0.084-0.86]. Patients who received >500 total MME had a 4.84 times greater probability (P = 0.002, 95% CI 1.8-13) of requiring opioids at 6-month follow-up. A subanalysis demonstrated individuals with preoperative opioid use who received <250 total MME had a 7.09 times smaller probability (P = 0.033, 95% CI 0.023-0.85) of requiring opioids at 6-month follow-up while those who received >500 total MME had a 5.43 times greater probability (P = 0.033, 95% CI 1.6-18) of requiring opioids at 6-month follow-up. Conclusion. Exceeding the threshold of 500 total MMEs in the immediate postoperative period after a TLIF is a significant risk factor that predicts continued opioid use at 6-month follow-up, particularly among patients with a history of preoperative opioid utilization.