Peri-Operative Narcotic Consumption Following Minimally Invasive Lumbar Decompression Surgery: A Stratification based upon BMI

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

Disclosures: 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, Abbas Naqvi BS None, Hamid Hassanzadeh MD None, Anton Jorgensen MD None, Sriram Sankaranarayanan MD None,

Introduction:
Minimally invasive spine surgery is associated with less soft tissue injury and faster postoperative recovery. However, postoperative narcotic consumption associated with these MIS techniques, as a function of patient BMI, have not been previously reported.

Aims/Objectives:
To assess the impact of patient body mass index (BMI) on the postoperative narcotic consumption following a one or two-level minimally invasive (MIS) lumbar decompression (LD) procedure.

Methods:
A cohort of 318 patients who underwent a primary one- or -two level MIS LD (laminectomy or diskectomy) for degenerative spinal pathology were retrospectively analyzed. Patients were stratified based upon their body mass index (Obesity: BMI>30.0Kg/m2). Patient demographics, comorbidity burden, smoking status, intraoperative parameters, and in-hospital outcomes were assessed. Cumulative and daily (postoperative day (POD) oral morphine equivalent (OME) doses were recorded and analyzed with regards to the day of discharge. Statistical analysis was performed with a 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 318 LD procedures included in this analysis, 124 (38.9%) were performed on obese patients (BMI: 36.2±5.5 Kg/m2) and 194 (61.1%) on non-obese patients (BMI: 25.5±2.9 Kg/m2). There were no significant differences in patient demographics, comorbidity burden, procedural times, rates of peri-operative complications, and length of hospitalization between cohorts. The cumulative narcotic consumption was comparable between obese and non-obese patients on all discharge days. (POD 0: 19.7±11.3 vs 17.3±11.9, p=0.09; POD 1: 67.5±53.4 vs 75.9±158.5 , p=0.11; POD 2: 95.0±96.3 vs 73.5±92.3, p=0.82; POD 3: 88.0±124.5 vs 128.3±88.1, p=0.67). In both cohorts, daily OME dose did not significantly differ as a function of the day of discharge.

Conclusions:
Obesity was not associated with a greater postoperative narcotic consumption following elective MIS LD surgery. Although larger prospective studies are warranted, these findings suggest that obesity does not significantly impact intraoperative parameters or postoperative opioid requirements following a minimally invasive LD procedure.