Cost-utility analysis of instrumented fusion versus decompression alone for grade i L4-L5 spondylolisthesis at 1-year follow-up a pilot study

Matthew D. Alvin, Daniel Lubelski, Kalil G. Abdullah, Robert G. Whitmore, Edward C. Benzel, Thomas E. Mroz

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Study Design: Retrospective 1-year cost-utility analysis. Objective: To determine the cost-effectiveness of decompression with and without instrumented fusion for patients with grade I degenerative L4-L5 spondylolisthesis at 1-year follow-up. Summary of Background Data: Despite its benefits to health outcomes, lumbar fusion is associated with substantial costs. This study analyzed the cost-effectiveness of instrumented fusion for grade I L4-L5 spondylolisthesis at 1-year follow-up. Materials and Methods: Four cohorts of 25 patients with grade I L4-L5 degenerative spondylolisthesis were analyzed: cohort 1 (decompression), cohort 2 (decompression with instrumented posterolateral fusion (PLF), cohort 3 (decompression with instrumented posterior lumbar interbody fusion/transforaminal lumbar interbody fusion), and cohort 4 (decompression with instrumented PLF and posterior lumbar interbody fusion/ transforaminal lumbar interbody fusion). One-year postoperative health outcomes were assessed based on Visual Analogue Scale, Pain Disability Questionnaire, and EuroQol 5 Dimensions questionnaires. Direct medical costs were estimated using Medicare national payment amounts and indirect costs were based on patient missed work days. Postoperative 1-year cost/utility ratios and incremental cost-effectiveness ratios (ICERs) were calculated. Cost-effectiveness was assessed using a threshold of $100,000/QALY gained. Results: Compared with preoperative health states, EuroQol 5 Dimensions QALY scores improved for all cohorts (P<0.01). The 1-year cost-utility ratio for cohort 1 was significantly lower ($56,610/QALY gained; P<0.01) than that for cohorts 2 ($116,991/QALY gained), 3 ($109,740/QALY gained), and 4 ($107,546/QALY gained). The 1-year ICERs relative to cohort 1 were: cohort 2 (dominated), cohort 3 ($1,060,549/QALY gained), and cohort 4 ($830,047/QALY gained). Conclusions: Decompression without fusion is cost-effective for patients with grade I L4-L5 spondylolisthesis. Decompression with fusion is not cost effective in a 1-year timeframe for these patients based on the threshold. Accordingly, although fusion is beneficial for improving health outcomes in patients with spondylolisthesis, it is not cost-effective when analyzing a 1-year timeframe based on the threshold. The durability of these results must be analyzed with longer term cost-utility analysis studies.

Original languageEnglish (US)
Pages (from-to)E80-E86
JournalClinical Spine Surgery
Issue number2
StatePublished - 2016
Externally publishedYes


  • Comparative Effectiveness
  • Cost-Effectiveness
  • Cost-Utility Ratio
  • Grade I
  • Outcomes
  • QALY
  • Quality Of Life
  • Spinal Fusion
  • Spondylolisthesis
  • cost/QALY

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine
  • Clinical Neurology


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