Association of inpatient opioid consumption on postoperative outcomes after open posterior spinal fusion for adult spine deformity.

Abstract

Opioids are the most commonly used analgesic in the postoperative setting. However, few studies have analyzed the impact of high inpatient opioid use on outcomes following surgery, with no current studies assessing its effect on patients undergoing spinal fusion for an adult spinal deformity (ASD). Thus, the aim of this study was to investigate risk factors for high inpatient opioid use, as well as to determine the impact of high opioid use on outcomes such as adverse events (AEs), hospital length of stay (LOS), cost of hospital admission, discharge disposition, and readmission rates in patients undergoing spinal fusion for ASD. A retrospective cohort study was performed using the Premier healthcare database from the years 2016 and 2017. All adult patients > 40years old who underwent thoracic or thoracolumbar fusion for ASD were identified using the ICD-10-CM diagnostic and procedural coding system. Patients were then categorized into three cohorts based on inpatient opioid use: Low MME (morphine milligram equivalents), Medium MME, and High MME. Patient demographics, comorbidities, treating hospital characteristics, intraoperative variables, postoperative AEs, LOS, discharge disposition, and total cost of hospital admission were assessed in the analysis. Multivariate regression analysis was done to determine independent predictors of high inpatient MME, prolonged LOS, and increased hospital cost. Of 1673 patients included, 417 (24.9%) were classified as Low MME, 840 (50.2%) as Medium MME, and 416 (24.9%) as High MME. Age significantly decreased with increasing MME (Low: 71.0% 65 + years vs Medium: 62.0% 65 + years vs High: 47.4% 65 + years, p < 0.001), while the proportions of patients presenting with three or more comorbidities were similar across the cohorts (Low: 20.1% with 3 + comorbidities vs Medium: 18.0% with 3 + comorbidities vs High: 24.3% with 3 + comorbidities, p = 0.070). With respect to postoperative outcomes, the proportion of patients who experienced any AE (Low: 60.2% vs Medium: 68.8% vs High: 70.9%, p = 0.002), extended LOS (Low: 6.7% vs Medium: 20.7% vs High: 45.4%, p < 0.001), or non-routine discharge (Low: 66.6% vs Medium: 73.5% vs High: 80.1%, p = 0.003) each increased along with total MME. In addition, rates of 30-day readmission were greatest among the High MME cohort (Low: 8.4% vs Medium: 7.9% vs High: 12.5%, p = 0.022). On multivariate analysis, medium and high MME were associated with prolonged LOS [Medium: OR 4.41, CI (2.90, 6.97); High: OR 13.99, CI (8.99, 22.51), p < 0.001] and increased hospital cost [Medium: OR 1.69, CI (1.21, 2.39), p = 0.002; High: OR 1.66, CI (1.12, 2.46), p = 0.011]. Preadmission long-term opioid use [OR 1.71, CI (1.07, 2.7), p = 0.022], a prior opioid-related disorder [OR 11.32, CI (5.92, 23.49), p < 0.001], and chronic pulmonary disease [OR 1.39, CI (1.06, 1.82), p = 0.018] were each associated with a high inpatient MME on multivariate analysis. Our study demonstrated that increasing inpatient MME consumption was associated with extended LOS and increased hospital cost in patients undergoing spinal fusion for ASD. Further studies identifying risk factors for increased MME consumption may provide better risk stratification for postoperative opioid use and healthcare resource utilization.