Lightning Podiums: Value and Outcomes in Spinal Surgery - Room 801B

Presented by: J. Ammerman

Author(s):

J. Ament(1), Z. Yang(1), E. Kulubya(2), W. Hsu(3), C. Thome(4), K. Kim(2)

(1) University of California Davis, Sacramento, CA, United States
(2) University of California Davis, Neurological Surgery, Sacramento, CA, United States
(3) Northwestern University, Orthopedic Surgery, Chicago, IL, United States
(4) University of Heidelberg, Neurological Surgery, Baden-Württemberg, Germany

Abstract

Background: Lumbar discectomy is considered a relatively straight-forward operation having predictable outcomes. However, lumbar herniation patients with large annular defects who undergo discectomy appear to be at high risk for reherniation, with concomitant poor outcomes, reoperations and incremental costs.

Purpose: We evaluated the cost-effectiveness of a bone-anchored annular closure device (ACD) used as an adjunct to discectomy compared to conventional discectomy (Control).

Methods: The analyzed population included both the Control and ACD-treated cohorts from a multicenter prospective RCT designed to assess safety and efficacy of the ACD. Patient follow-up visits were at 6 weeks and 3, 6, 12, and 24 months after the primary discectomy. Health states were created by projecting visual analogue scale (VAS) onto Oswestry Disability Index (ODI). Direct costs were calculated based on pertinent diagnosis delated groups (DRGs), post-operative medications, reoperations and surgery-related complications by applying inpatient 2017 Medicare rates to type/frequency of these measures. Device cost was assumed to be $3000 US-dollars. Indirect costs were calculated for lost work days using 2016 US average annual wages. Quality of life of determined using SF-36 and SF-6D captured during the RCT. Final input parameters were used to inform a cohort Markov model based on 6 derived health states (Figure 1). The resulting incremental cost-effectiveness ratio (ICER) in units $/QALY (quality adjusted life year) was then compared to accepted willingness-to-pay (WTP) thresholds.

Results: A strong correlation (R2=0.826, P< 0.001) was found by projecting VAS onto ODI. In this base case analysis, from a healthcare perspective (direct costs only) ACD had an average of 1.54 QALYs gained after 24-months compared to 1.50 QALYs for the control group. ACD was associated with $2,498 greater average cost. The ICER of ACD compared to control was therefore $76,023 per QALY at two years. From a societal perspective (indirect costs included), ACD costs, on average, $224 more than control, resulting in an ICER of $6,826 per QALY at two years.

Conclusions: The 2 year ICER of ACD compared with the traditional lumbar discectomy is lower than the commonly accepted WTP- threshold of $100,000 per QALY in the USA. Accounting for the societal impact augments the ICER further, suggesting that the ACD could substantially improve the cost-effectiveness of lumbar discectomy, particularly in patients at high-risk for reoperation.

Figure 1. Markov Model Schematic