A Medicare Beneficiaries Analysis of Minimally Invasive Lumbar Diskectomies: Single Surgeon Experience

Presented at SMISS Annual Forum 2014
By Kern Singh MD
With Sreeharsha V. Nandyala BA, Alejandro Marquez-Lara MD, Islam Elboghdady , Eric Sundberg MD, Hamid Hassanzadeh MD, Anton Jorgensen MD, Blaine Manning BS, 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, Hamid Hassanzadeh MD None, Anton Jorgensen MD None, Blaine Manning BS None, Sriram Sankaranarayanan MD None,

Introduction:
Medicare (MC) patients often carry a significant comorbidity burden that may potentiate surgical complications or worsened outcomes. Few studies have assessed minimally invasive lumbar diskectomy within this demographic.

Aims/Objectives:
To assess the surgical outcomes and safety of a primary 1 and 2 level minimally invasive (MIS) lumbar diskectomy in Medicare beneficiaries.

Methods:
A total of 251 primary 1 and 2 level MIS lumbar diskectomies performed for degenerative spinal pathology between 2009-2013 were analyzed. Patients were separated as a function of their MC payor status (MC vs non-MC). Patient demographics, comorbidity Index (CCI), intraoperative parameters, perioperative outcomes, visual analogue scores (VAS) and postoperative complications were assessed. Statistical analysis was performed with independent sample T-tests for continuous variables and Chi-square analysis for categorical data. An alpha level of <0.05 denoted statistical significance.

Results:
Of the 251 patients who underwent an MIS lumbar diskectomy, 19 (7.6%) were Medicare beneficiaries. MC patients were on average older (61.6±15.7 vs 40.6±11.0, p<0.05) and demonstrated a greater comorbidity burden (CCI: 3.56±1.99 vs 1.15±1.46, p<0.05). The proportion of smokers and the pre-operative VAS scores were comparable between the study cohorts. The MC cohort incurred a longer operative time (50.6±25.6 vs 39.5±18.8 min, p<0.05) and hospitalization (26.9±24.3 vs 12.9±12.7 hours, p<0.05) than the non-MC cohort. In addition, MC patients demonstrated a greater rate of in-hospital medical complications (urinary retention) (5.3% vs 0.0%, p<0.05). In contrast, the payor status did not significantly impact the postoperative VAS scores and the rate of reherniation or revision/re-operation.

Conclusions:
In this analysis MC patients were older and demonstrated an increased comorbidity burden, which likely explains the greater in-hospital complications and length of stay. Despite the increased hospital resource utilization, Medicare patients who underwent an MIS lumbar diskectomy demonstrated significant improvements in pain that were comparable to that of the non-MC cohort, without an increased risk of re-herniation or re-operation.