Journal of NeuroEngineering and Rehabilitation

Background There are about 185,000 amputations conducted per year in the U.S. [ 1 ] . Currently, approximately 1.9 million individuals are living with limb loss according to the Centers for Disease Control and Prevention [ 2 ] , a figure expected to rise to 3.6 million by 2050 [ 1 ] . Of this num- ber, it is estimated that 18.5 to 21.0% are transfemoral amputees [ 3 , 4 ] . Transfemoral amputation, or the re- moval of a limb above the knee joint, is performed to re- move ischemic, infected, or irreversibly damaged tissue and is generally a life-saving procedure. About 82% of transfemoral amputations are due to peripheral artery disease and/or diabetes, followed by trauma, cancer, in- fection, and congenital defects [ 5 , 6 ] . Advanced technologies can help transfemoral ampu- tees improve functional mobility and as a result, quality of life. A transfemoral amputee often has difficulty in regaining normal movement. For example, transfemoral amputees must use 35 – 65% more energy [ 7 – 10 ] to walk than a person with two legs due to complexities in the knee joint. Over the last decade, major technological ad- vancements such as microprocessors, and their associ- ated load and position sensors have catalyzed the modernization of prosthetics [ 11 ] . Such advanced pros- thetic knees and feet were developed to allow for safer movements across a range of walking environments and improving user quality of life [ 11 – 13 ] . Despite the rapid progress in advanced technologies, our healthcare payment system, however, has not yet evolved simultaneously, treating prosthetics as commod- ity products and emphasizing cost-cutting rather than good value for the money. Currently, the Centers for Medicare and Medicaid Services (CMS), the Department of Veterans Affairs, and private insurance companies re- strict reimbursement of prosthetics based on the Medi- care Functional Classification Level, an index for classifying the functional mobility and productivity po- tential of individuals with lower limb loss [ 14 , 15 ] . Within Medicare, amputees often have to pay about 20% of the device cost out-of-pocket when they purchase a new device; if a prosthetic device is not covered, ampu- tees have to pay for the entire device out of pocket. Con- sequently, patients often choose low-cost prosthetic devices and may not realize their potential in functional mobility [ 16 ] . With increasing cost-cutting pressure in recent years, payers have shifted part of such pressure onto the prosthetics industry. For example, citing a 2011 report by the Office of Inspector General [ 17 ] , the CMS issued new local coverage rules in 2015 to tighten the rules for reimbursing lower-limb prosthetics. An open and candid dialog among stakeholders would help us strike the right balance between improving clin- ical outcomes and controlling healthcare cost, and this is where robust evidence should play a critical role, such as evidence for the incremental value of advanced prosthet- ics in comparison to conventional prosthetics. On the one hand, payers should ensure patient access to ad- vanced technologies with proven health benefits, but on the other hand, they have the fiduciary obligation to contain ever-expanding healthcare costs. To address this, quality clinical and economic data, as well as rigor- ous studies, are required to demonstrate the value of prosthetics and associated services. In the absence of head-to-head clinical trial data, a modeling study was conducted to leverage existing evidence to assess the cost-effectiveness of advanced prosthetics such as microprocessor-controlled prosthetic knees compared to non-microprocessor alternatives from the societal perspective. Methods The clinical and economic benefits of microprocessor-controlled prosthetic knees (MPK) were compared with those of non-microprocessor controlled prosthetic knees (NMPKs) from a societal perspective, and the results are summarized as an incremental cost-effectiveness ratio (ICER) — a commonly accepted measure for cost-effectiveness or value for money. ICER is defined as the additional resource requirements per unit of additional health gained, which is typically mea- sured by quality-adjusted-life-years (QALY). The analysis assessed various clinical and economic endpoints, in- cluding physical function, quality of life, direct health- care costs, and indirect costs such as the impact on caregiving expenses, transportation expenses, and work productivity. All costs were inflated to 2016 U.S. dollars using the medical care component of the Consumer Price Index [ 18 ] and, when applicable, were converted to U.S. dollars using the exchange rate at the time the study was con- ducted [ 19 ] . This study was approved by RAND ’ s Hu- man Subjects Protection Committee. Target population The analysis focuses on the Medicare population, which includes a diversely aged patient group, because CMS not only represents the largest payer for prosthetic devices in the country but also sets the market standard for reim- bursement levels against which commercial payers and the Department of Veterans Affairs often benchmark. Be- sides, since unilateral K3 and K4 transfemoral amputees have historically been the primary users of advanced pros- thetics, they are the target population of the main analysis. Unilateral K1 and K2 transfemoral amputees were exam- ined in the sensitivity analysis. Dobson and DeVanzo LLC provided basic characteristics of the target populations for the simulation model based on the 2011 – 2014 Medicare claims data (see Additional file 1 : Table S1). Chen et al. Journal of NeuroEngineering and Rehabilitation 2018, 15 (Suppl 1):62 Page 50 of 72