Opioid Requirements in Obese Patients following a Minimally Invasive Transforaminal Lumbar Interbody Fusion

Presented at SMISS Annual Forum 2014
By Abbas Naqvi BS
With Kern Singh MD, Sreeharsha V. Nandyala BA, Alejandro Marquez-Lara MD, Islam Elboghdady , Eric Sundberg MD, Hamid Hassanzadeh MD, Anton Jorgensen MD, Khaled Aboushaala MD,

Disclosures: Abbas Naqvi BS None Kern Singh MD A; CSRS Resident Grant. B; DePuy, Zimmer, Stryker, CSRS, ISASS, AAOS, SRS, Vertebral Column - ISASS. D; Avaz Surgical, LLC, Vital 5, LLC. F; Zimmer, Stryker, Pioneer, Lippincott Williams & Wilkins, Th, Sreeharsha Nandyala BA None, Alejandro Marquez-Lara MD None, Islam Elboghdady None, Eric Sundberg MD None, Hamid Hassanzadeh MD None, Anton Jorgensen MD None, Khaled Aboushaala MD None,

Introduction:
Obese patients are perceived to require greater narcotic utilization to achieve appropriate postoperative pain relief. Understanding the differences in narcotic requirements based upon the patient’s body mass index (BMI) is important to reduce the risk of toxicity and side effects that may result from weight-based narcotic dosing.

Aims/Objectives:
To evaluate the impact of body mass index (BMI) on opioid utilization in the setting of a minimally invasive transforaminal lumbar interbody fusion (TLIF).

Methods:
A cohort of 136 patients who underwent a primary single-level TLIF procedure for degenerative spinal pathology was analyzed. Patients were stratified based upon their body mass index (Obesity: BMI>30.0Kg/m2) and assessed with regards to patient demographics, comorbidity burden, smoking status, intraoperative parameters, hospital outcomes. Cumulative and daily (postoperative day (POD)) in-hospital narcotic requirements (expressed in oral morphine equivalent (OME) doses) were also analyzed. Statistical analysis was performed with chi-squared test for categorical variables and Student-Test for continuous variables. OME means were compared utilizing non-parametric analysis to adjust for skewedness. A p-value of <0.05 denoted statistical significance.

Results:
Of the 136 MIS TLIF procedures included in this analysis 62 (45.5%) were performed on obese patients (BMI: 36.5±6.1Kg/m2) and 74 (54.5%) on non-obese patients (BMI: 25.7±2.8 Kg/m2). Patient demographics, comorbidity burden, rates of intra-operative complications, and length of hospitalization were comparable between cohorts. Obese patients demonstrated greater operative times (133.5±48.6 vs 118.0±33.9; p<0.05). Obese and non-obese patients demonstrated a delay in discharge with higher OME doses on POD 0 and POD 2 respectively. The cumulative narcotic consumption was comparable between obese and non-obese patients for each discharge day (POD 1: 36.7±15.7 vs 44.7±27.6, p=0.78; POD 2: 92.1±57.1 vs 68.4±34.9, p=0.11; POD 3: 96.1±48.3 vs 121.4±91.1, p=0.58).

Conclusions:
This analysis demonstrated that obesity is not associated with increased narcotic consumption following a single-level MIS TLIF procedure. A group of patients who received higher narcotic doses experienced a delay in discharge. Weight-based opioid dosing during the immediate postoperative period may not be warranted to achieve appropriate pain control in obese patients following an MIS TLIF.