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The Spine Blog

Friday, October 18, 2019

Is Adult Deformity Surgery Cost-Effective?

Adult deformity surgery improves patient reported outcomes in properly selected patients. However, these major surgeries are very expensive and have high complication and revision rates. Cost-effectiveness analysis (CEA) attempts to quantify the cost of an intervention relative to its utility to the patient (measured over time in terms of quality adjusted life years, or QALYs). In formal CEA, the incremental cost-effectiveness ratio (ICER) is used to compare the incremental cost and benefit of a more effective and more expensive treatment to a less effective, less expensive treatment. Generally, an ICER of less than $100,000/QALY is considered cost-effective. In the current study, Dr. Carreon and colleagues used the data from the Adult Symptomatic Lumbar Scoliosis trial to determine the ICER for adult deformity surgery compared to non-operative treatment. This study include 81 patients who were initially randomized to or chose surgery compared to 81 patients who initially were randomized to or chose non-operative treatment. All patients had follow-up through at least 5 years. The data were analyzed on an intent-to-treat basis, and this resulted in the data of 24 patients in the non-operative group who underwent surgery within the first 5 years being attributed to the non-operative group. Over 5 years, they found the surgery group gained an average of 2.44 QALY at a cost of $96,000, compared to 0.75 QALY at a cost of $49,546 for the non-operative group. This yields a very cost-effective ICER of $27,480/QALY for surgery.

This is the first well-done, formal CEA comparing surgery to non-operative treatment for adult spinal deformity. Other prior studies have included only surgery data or estimated non-operative outcomes. The current study has limitations typical for observational data including some baseline measured and likely unmeasured differences between the two groups. The authors had to decide to analyze the data on an intent-to-treat or on an as-treated basis, both of which have limitations. The chose intent-to-treat, despite the fact that nearly one third of the patients classified as non-operative had surgery. This resulted in the non-operative group having greater QALY gains and costs compared to the patients who truly remained non-operative throughout the course of the trial. It would have been helpful if the authors had performed an as-treated analysis to compare the results to the intention-to-treat analysis, though a brief inspection of their five-year decision tree suggests that the results would have probably not changed much. This paper strongly supports the cost-effectiveness of adult deformity surgery for well-selected patients. The current challenge for the spine surgeon is determining which patients are appropriate for surgery and which are at too great a risk for a bad complication. Models have been developed to help with this prediction, though they have not been validated to a point where they are useful clinically. While CEA is somewhat abstract in the United States healthcare system in which care is not officially rationed, this paper should be helpful to justify the use of adult deformity surgery in government-run healthcare systems in other countries and to insurance companies in the US.

Please read Dr. Carreon's article on this topic in the November 1 issue. Does this change how you see the value of adult deformity surgery? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor