Are Ceramic-on-Poly Implants a Cost-Effective Alternative for THA?
A Markhov decision model showed that even if ceramic-on-polyethylene implants were more expensive than metal-on-polyethylene implants, lower revision rates could make the ceramic-on-poly option more cost-effective in certain patients.
Metal-on-metal implants are rarely, if ever, used for total hip arthroplasty (THA) anymore. Ceramic-on-ceramic bearing surfaces have their proponents, but they have demonstrated clinical issues as well.
So which bearing surface combination can offer the implant longevity patients and their surgeons want in a cost-effective manner that keeps the hospital happy?
Researchers from OrthoCarolina Research Institute recently sought to answer that question with a comparison of ceramic-on-polyethylene (CoP) and metal-on-polyethylene (MoP) bearing surfaces.
The results of the study were presented at the recent annual meeting of the International Society for Pharmacoeconomics and Outcomes Research.
CoP bearing surfaces are the newer of the two options, and they’re more expensive than MoP bearing surfaces. But that may not tell the entire story.
The investigators, therefore, constructed a Markov decision model to determine what the 20-year revision rate for CoP bearing surfaces would have to be in order for CoP implants to be more cost-effective than MoP implants.
Data sources for the study included:
- The trade journal Orthopedic Network News for average purchase prices for CoP and MoP implants
- The HealthEast Joint Registry for the 20-year cumulative revision rate for MoP bearings
- The National Premier Research Hospitalization Database (475 hospitals) for costs associated with hospitalization for primary and revision THA among patients age 45 years and older who received a CoP or MoP bearing (20,398 patients)
Unadjusted data from the Premier database showed that the hospitalization cost related to a THA with a CoP bearing surface was $325 more than for a THA with an MoP bearing surface.
When the costs were adjusted for patient demographics, MS-DRG, payer, length of stay, discharge status, hospital teaching status, urban-rural, geographic location, and hospital procedure volume, the difference grew to $1,003.
In addition, according to Orthopaedic Network News, the average purchase price for a CoP implant was $600 more than for an MoP implants.
Finally, the HealthEast database indicated that the 20-year revision rate for MoP implants was 14.5/100 THA procedures.
With that data, the researchers constructed a Markov decision model that allowed them to see when the use of the CoP implant would be more cost-effective than use of the MoP implant across multiple combinations of 20-year CoP revision rates, patient age groups, and surface bearing costs ($325, $600, and $1,003 cost differences).
For example, at the $1,003 cost difference, the CoP revision rate for a 70-year-old patient would have to be 9.0/100 THA procedures for the CoP implant to be more cost-effective than the MoP implant. That’s 5.5 fewer revision procedures per 100 THAs for CoP implants than for MoP implants.
That number is attainable, according to the researchers: Data from the UK National Joint Registry show that use of CoP implants can be expected to cut the long-term revision rate by approximately 5.5 revisions/100.
With that in mind, the researchers said, “70 years of age is a fair estimate of a cost- effectiveness ‘age breakpoint’ at the $1,003 cost difference.”
Interestingly, they noted that the market in the U.S. has already spoken: Their data show that orthopaedic surgeons have been shifting to CoP bearing surfaces for the past several years, even absent data on cost-effectiveness of this choice versus the less-expensive MoP option.
This shift “can be justified depending on the patient age, cost of the device, and actual CoP revision rate,” the researchers said. “All else equal, shifting all THAs in patients below age 70 to CoP and over 70 to MoP can be cost justified, even in the highest cost difference case.”
Carnes KJ, Odum SM, Troyer JL, Fehring TK. What is the cost-effective bearing surface choice in primary total hip arthroplasty. Presented at the International Society for Pharmacoeconomics and Outcomes Research 20th Annual International Meeting, May 16-20, 2015, in Philadelphia, Pennsylvania.