Surgical Survivorship of Lumbar Diskectomy in Medicare Beneficiaries

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, Khaled Aboushaala MD, Junyoung Ahn ,

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, Khaled Aboushaala MD None, Junyoung Ahn None,

Introduction:
Lumbar decompression surgery has demonstrated to be safe and effective for appropriately selected patients. However, the longevity of minimally invasive lumbar diskectomy procedures, as a function of Medicare status, has not been previously described.

Aims/Objectives:
To compare the one-year survival between Medicare (MC) and non-Medicare patients undergoing a minimally invasive (MIS) 1 or 2 level lumbar diskectomy.

Methods:
251 patients who underwent a primary 1 or 2 level lumbar diskectomy for degenerative spinal pathology between 2007-2013 were retrospectively reviewed. Only those with a minimum follow-up time of 12 months were included for analysis. Patients were stratified based upon the primary payor status (MC and non-MC) and assessed with regards to patient demographics, Charlson comorbidity index (CCI), and body mass index (BMI). The incidence and prevalence of revision surgeries at 12-months were calculated by the Kaplan-Meier method. Survivorship distributions were compared with the Log-Rank test and a p-value of <0.05 was utilized to denote statistical significance.

Results:
Of the 251 lumbar diskectomies identified, 192 demonstrated a minimum follow up of one-year. Medicare patients were older (64.4±13.5 vs 39.5±10.9, p<0.05), and demonstrated a greater comorbidity burden (CCI: 4.00±1.78 vs 1.08±1.30, p=0.50) than non-MC patients. One year after index lumbar decompression, 6.2% (1/16) and 14.2% (25/176) of MC and non-MC patients, respectively, required a revision procedure. There were no significant differences in the type of revision surgery (arthrodesis vs decompression) between the two cohorts (p=0.27). Kaplan-Meier analysis predicted a survival rate of 93.8% (n=15/16) at 1 year in MC patients and 85.8% (n=151/176) in non-MC patients. Survivorship distributions between the two cohorts did not significantly differ. (Log-Rank: Chi-square 0.83, p=0.36).

Conclusions:
Roughly one out of seven patients (13.5%) who underwent an MIS lumbar diskectomy in our series required a revision procedure within the first 12-months. Despite the older and more comorbid patient population of Medicare beneficiaries, the one-year survival was comparable to non-Medicare patients. Although further long-term data is warranted, these findings suggest that MIS techniques are effective alternatives for lumbar decompression procedures.