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Study Shows Economic Value of Advanced Transfemoral Prostheses

In spite of the advances in prosthetic technologies, payers—primarily the Centers for Medicare & Medicaid Services—have questioned the value of advanced prosthetic devices and related services. Payments for prosthetic devices declined 15 percent during the 2010-2014 time period, and a further attempt was made to tighten the rules in 2015. As a result, the American Orthotic & Prosthetic Association (AOPA) commissioned RAND, Santa Monica, California, to perform a comprehensive, independent, validated study quantifying the value of prosthetic services. The study’s initial scope was expanded to include an economic analysis for four types of advanced transtibial and transfemoral prostheses, including dynamic response feet, microprocessor knees (MPKs), microprocessor-controlled ankle-foot systems, and powered ankle-foot systems. RAND and AOPA have released the results of the study that simulated the differential clinical outcomes and cost of MPKs compared to nonmicroprocessor-controlled knees (NMPKs).

RAND conducted a literature review of the clinical and economic impacts of prosthetic knees, convened technical expert panel meetings, compiled input parameters, and constructed and implemented a simulation model over a 10-year time period for people who had Medicare, a unilateral transfemoral amputation, and a K3 or K4 functional level. RAND found that compared to NMPKs, MPKs are associated with sizeable improvement in physical function and reductions in incidences of falls and osteoarthritis. The effect on low back pain, depression, obesity, diabetes, and cardiovascular disease could not be quantified due to the lack of data, according to the authors.

The study showed that 26 percent of patients who received prosthetic limbs with MPKs will fall per year, contrasted to patients receiving NMPKs, of whom 82 percent will fall annually. In addition, 10.4 percent of these have a range of medical costs: 7 percent of these medical falls result in death (cost $27,338); 40 percent result in major injuries with inpatient and/or skilled nursing facility treatment (cost $23,363), and the remaining 53 percent have minor injuries (cost $1,091). There are 22 fall-related deaths per 10,000 patient years for the NMPK users, and four fall-related deaths per 10,000 patient years for the those with MPKs—18 lives saved by MPK usage, according to the study. The simulation data showed 66 injurious falls with the MPK, and 289 with the NMPK. MPK amputees have a lower incidence of osteoarthritis due to lower vertical ground force (14 percent for MPK compared to 20 percent for NMPK), although evidence is not robust, the study suggests. While MPK users have about $4,220 lower direct and indirect healthcare costs per year than NMPK users, the higher cost for the prosthesis exceeds that yearly savings. RAND’s simulation results show that over a 10-year period, compared to NMPKs, MPKs are associated with an incremental cost of $10,604 per person and an increase of 0.91 quality adjusted life year per person, resulting in an incremental cost of $11,606 per quality adjusted life year gained.

The results suggest that the incremental cost of MPKs are in line with commonly accepted criteria for good value for money and with the incremental cost of other medical devices that are currently covered by U.S. payers.