Plastic Surgery Research Council

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Tibial Nerve Decompression for the Prevention of theDiabetic Foot: A Cost-Utility Analysis Using Markov Model Simulations
Samuel Sarmiento, MD, MPH, MBA1, A Lee Dellon, MD, PhD1, Kevin D. Frick, PhD2.
1Johns Hopkins University School of Medicine, Baltimore, MD, USA, 2Johns Hopkins University School of Business, Baltimore, MD, USA.

Purpose: We examined whether tibial neurolysis performed as a surgical intervention for patients with diabetic neuropathy and superimposed tibial nerve compression in the prevention of the diabetic foot is cost saving and cost effective when compared to the current prevention program as per the Centers for Medicare and Medicaid Services (CMS).
Methods: A Markov model was used to simulate the effects of standard prevention compared to tibial neurolysis on the long-term costs associated with foot ulcers and amputations. This model included eight health states. A baseline analysis was built on a five-year model to determine the cumulative incidence of foot ulcers and amputations with each strategy. Subsequently, a cost-effectiveness analysis and cohort-level Markov simulations were conducted with a model composed of 20 six-month cycles. The outcomes explored were quality adjusted life years (QALYs); the incremental cost-effectiveness of tibial neurolysis in comparison with standard treatment and the net monetary benefits of tibial neurolysis. A sensitivity analysis was also performed.
Results: When compared to standard prevention, for a patient population of 10,000, surgery prevented a total of 1,447 ulcers and 409 amputations over a period of 5 years. In a subsequent analysis that consisted of 20 six-month cycles (10 years), the incremental cost of tibial neurolysis compared to current prevention was $12,772.28. The quality-adjusted life years were 6.30 for tibial neurolysis versus 5.90 for current prevention, with an incremental effectiveness of 0.41 QALYs. The incremental cost-effectiveness ratio (ICER) for surgery was $31,330.78. In relation to survival, given the difference in death rates between the two strategies, survival was 73% for those receiving medical prevention compared to 95% for those undergoing surgery.
Conclusion: These results suggest that among patients with diabetic neuropathy and superimposed nerve compression, surgery is more effective at preventing serious comorbidities and is associated with a higher survival over time. While more costly initially, surgery is more cost-effective than the current prevention strategy. It also generated greater long-term economic benefits than those obtained with standard prevention. These results coupled with the QALYs gained make surgery the strategy worth considering.

Table 1. Risk groups for developing foot ulcers among diabetic patients.
Risk GroupCharacteristicsSuitability for Surgery
1—Low RiskDiabetes but no other specific risk factors for foot ulcers.Not unless symptoms develop or positive neurosensory testing
2—At RiskDiabetes plus sensory neuropathy identified by symptoms and neurosensory testing.Ideal candidates
3—Increased RiskDiabetes complicated by sensory neuropathy and peripheral vascular disease and/or foot deformity.Poor candidates
4—High RiskDiabetic patients with at least one previous foot ulcer or amputation.Poor candidates

Table 2. Baseline cohort simulation results comparing the incidence of foot ulcers over 5 years by risk group between the two strategies at 80% and 25% reduction. The total number of ulcers and amputations that would be prevented by surgery is shown.
Current PreventionTibial Neurolysis
Foot ulcers by risk group80%25%
1—Low risk13326103
2—At risk20996521825
3—Increased risk18926451721
4—High risk528627055382
Total ulcers prevented-5382379
Total amputations prevented-2154932
Cohort n=10,000.

Table 3. Cost effectiveness rankings.
StrategyCost ($)Incremental Cost ($)Effect (QALY)Incremental Effect (QALY)ICER ($/QALY)Net Monetary Benefit
Current Prevention22,751.275.90566,766.25
Tibial Neurolysis35,523.5512,772.286.300.4131,330.78594,759.88
Costs in US dollars. Net monetary benefit uses a willingness-to-pay of $100,000. QALY, quality-adjusted life years. ICER, incremental cost-effectiveness ratio.

Figure 1. Trends observed over a 10-year simulation period (20 six-month stages) showing a considerably higher probability of preventing foot ulcers in the surgical intervention strategy. Amputations and mortality are also lower in this group.

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