Analysis of national rates, cost, and sources of cost variation in adult spinal deformity

Corinna C. Zygourakis, Caterina Y. Liu, Malla Keefe, Christopher Moriates, John Ratliff, R. Adams Dudley, Ralph Gonzales, Praveen V. Mummaneni, Christopher P. Ames

Research output: Contribution to journalReview articlepeer-review

66 Scopus citations


BACKGROUND: Several studies suggest significant variation in cost for spine surgery, but there has been little research in this area for spinal deformity. OBJECTIVE: To determine the utilization, cost, and factors contributing to cost for spinal deformity surgery. METHODS: The cohort comprised 55 599 adults who underwent spinal deformity fusion in the 2001 to 2013 National Inpatient Sample database. Patient variables included age, gender, insurance, median income of zip code, county population, severity of illness, mortality risk, number of comorbidities, length of stay, elective vs nonelective case. Hospital variables included bed size, wage index, hospital type (rural, urban nonteaching, urban teaching), and geographical region. The outcome was total hospital cost for deformity surgery. Statistics included univariate and multivariate regression analyses. RESULTS: The number of spinal deformity cases increased from 1803 in 2001 (rate: 4.16 per 100 000 adults) to 6728 in 2013 (rate: 13.9 per 100 000). Utilization of interbody fusion devices increased steadily during this time period, while bone morphogenic protein usage peaked in 2010 and declined thereafter. The mean inflation-adjusted case cost rose from $32 671 to $43 433 over the same time period. Multivariate analyses showed the following patient factors were associated with cost: age, race, insurance, severity of illness, length of stay, and elective admission (P < .01). Hospitals in the western United States and those with higher wage indices or smaller bed sizes were significantly more expensive (P < .05). CONCLUSION: The rate of adult spinal deformity surgery and the mean case cost increased from 2001 to 2013, exceeding the rate of inflation. Both patient and hospital factors are important contributors to cost variation for spinal deformity surgery.

Original languageEnglish (US)
Pages (from-to)378-387
Number of pages10
JournalClinical neurosurgery
Issue number3
StatePublished - Mar 1 2018
Externally publishedYes

Bibliographical note

Funding Information:
Dr Zygourakis has received travel grants from Nuvasive and Globus to attend resident education courses. Ms Keefe is a consultant for DePuy Spine. Dr Ratliff is a consultant and receives royalties and travel funding from Stryker. Dr Mummaneni has received grants and honoraria from AOSpine, honoraria from Globus and DePuy, royalties from Thieme, Springer, and Taylor and Francis publishers, and is a stock holder in Spinicity/ISD. Dr Ames has received grants and research funding from DePuy Synthes Spine, is a consultant for DePuy, Medtronic, and Stryker, is a stock/shareholder with Baxano and Doctor’s Research Group, and receives royalties from Aesculap and Biomet Spine. Dr Zygourakis is supported by a research fellowship from the UCSF Center for Healthcare Value. The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Publisher Copyright:
Copyright © 2017 by the Congress of Neurological Surgeons.


  • BMP
  • Cost of surgery
  • Interbody fusion devices
  • National inpatient sample (NIS) database
  • Scoliosis
  • Spinal deformity
  • Spinal fusion


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