Clinical studyA cost utility analysis of treating different adult spinal deformity frailty states
Introduction
As healthcare in the United States shifts to a value based system, improving the stratification of patient populations with cost-utility analyses becomes increasingly important. Spine care currently costs approximately $90 billion annually and the prevalence of Adult Spinal Deformity (ASD) in patients over 60 years old has been reported as high as 68% [1], [2]. With technological advances in treating ASD, the number ASD surgeries performed has more than doubled over a decade in the United States [3]. These complex procedures carry a significant cost burden as they require highly trained personnel for many hours and involve multiple implant devices. Furthermore, with the population over the age of 65 expected to double over the next few decades it is critical to gain a more comprehensive understanding of the implications of the increase in ASD treatment from both an outcomes and cost perspective [4].
Cost-utility analyses assess an intervention’s cost-effectiveness by calculating a ratio of associated costs and utility gained based upon a patient reported outcome scale [5]. Quality-adjusted life year (QALY) comprehensively combines both quality and length of life in a single measurement [6]. This utility measure estimates the potential clinical benefit of an intervention. In spine research, reimbursement data serves as the standard cost proxy in these calculations. Other cost measurements have been used such as cost-to-charge ratios, case-costing databases and time driven activity-based costing [7]. Reimbursements remain the standard method in these analyses due to its ease of access, ability to be compared across specialties and utility in understanding societal willingness to pay [7].
The cost/QALY metric allows stakeholders to better understand the value of an intervention and to create a threshold under which an intervention would be considered cost-effective. The World Health Organization (WHO) has determined the threshold value for cost effectiveness when analyzing cost-utility ratios is one to three times gross domestic product (GDP) per capita [6], [8]. According to the International Monetary Fund, in 2018 the United States GDP per capita was $62,606; therefore, $187,818 represents the upper threshold of the United States cost/QALY willingness to pay [6], [9], [10].
Frailty has become a preferred measure to characterize aging and predict mortality. Frailty can serve as an improved predictor of decline in a patient’s ability to function independently compared to chronological age [11], [12], [13], [14]. Using the methods of Mitnitski et al. and Searle et al. for frailty indices, the ASD frailty index (ASD-FI) was developed with a prospective database of ASD patients. This index stratifies patients into three categories: not frail (NF), frail (F), and severely frail (SF) [15], [16]. Although older chronological age can serve as a predictor for complications, increased length of hospital stay, and worse outcomes after ASD surgery, patients physiologic age can be better represented with the ASD-FI than with chronological age [17], [18].
The primary objective of this study is to determine the cost-utility of ASD surgery between patients in different frailty states. Currently the cost of treating each frailty state is unknown. This analyses will be critical in understanding and evaluating the cost-effectiveness of treating specific patient populations with ASD. As ASD related costs continue to rise, optimizing patient selection for surgical intervention will play a significant role in not only maximizing clinical success, but also for maximizing the cost-utility of treating these patients [19], [20], [21].
Section snippets
Study design and data source
This study was an Institutional Review Board (IRB) approved retrospective review of patients presenting to a single academic spine center between November 2013 and November 2018. Inclusion criteria consisted of age >18 years, operative treatment for adult spinal deformity (ASD), with available radiographic, surgical, and health related quality of life data. ASD was defined as scoliosis ≥20°, sagittal vertical axis (SVA) ≥5 cm, pelvic tilt (PT) ≥25°, or thoracic kyphosis (TK) ≥60° and undergoing
Patient demographics
79 ASD patients met inclusion criteria. The mean age of the cohort was 51.0 ± 6.8 years old, 76% were women, the average BMI was 26.7 ± 6.8, and the average Charlson Comorbidity Index was 1.81 ± 0.8 (Table 1). At baseline, there were 48 NF, 26 F, and 4 SF pts. The average baseline frailty for NF pts was 0.13 ± 0.08, 0.39 ± 0.06 for F, and 0.59 ± 0.08 for SF pts. Breakdown of certain demographic and surgical descriptors by baseline frailty group may be seen in Table 2.
Surgical details
ASD correction for these
Discussion
The latest National Inpatient Sample (NIS) reveals that the ASD surgery volume increased by 112.5% in seven years [3]. Due to the high resource utilization associated with treating ASD, these procedures have become a primary target for increased scrutiny [30], [31]. Analyzing the costs and quality outcomes associated with ASD surgery in stratified patient populations can strengthen our understanding of which patients could benefit from ASD surgery.
The ASD-FI was designed to assess surgical risk
Conclusion
This study analyzes the cost utility of surgically treating ASD in different frailty states. Frail and severely frail patients had lower cost/QALY compared to non-frail patients at two years and life expectancy. In addition, when compared to a non-operative cohort of ASD patients, frail and severely frail patients had lower ICER values. While these results support operative correction of frail and severely frail patients, it is important to note that these patients are often at worse baseline
Funding information
No funding was received in relation to the creation of this work.
Disclosures
Hamid Hassanzadeh, MD
4Web: Stock or stock Options
DePuy, A Johnson & Johnson Company: Paid consultant
Globus Medical: Paid presenter or speaker
Medtronic: Paid consultant; Paid presenter or speaker; Research support
Misonix: Stock or stock Options
Norvartis: Stock or stock Options
Nuvasive: Paid consultant; Paid presenter or speaker; Stock or stock Options
Orthofix, Inc.: Paid presenter or speaker; Research support
Pacira: Stock or stock Options
Pfizer: Paid consultant; Research support
Scoliosis
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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