Sequencing or Culturing to Diagnose PJI, Which Costs Less?

Next-generation sequencing (NGS) to diagnose periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is more sensitive than culture-based techniques but is it cost-effective?

A new study “Next-Generation Sequencing vs Culture-Based Methods for Diagnosing Periprosthetic Joint Infection After Total Knee Arthroplasty: A Cost-Effectiveness Analysis,” details these issues in the July 2019 edition of The Journal of Arthroplasty.

Wayne Moschetti, M.D., M.S., section chief of the Division of Adult Reconstructive Surgery and assistant professor in the Geisel School of Medicine at the Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, and co-author explained the issue to OTW, “Working in a tertiary academic referral center we care for a lot of patients with periprosthetic joint infections. Diagnosis at times can be challenging with traditional culture-based methods. Next-generation sequencing potentially provides an opportunity to help diagnosis infection in some of these challenging cases but at an added cost. This made it a good topic for a cost-effectiveness analysis.”

To answer the cost effectiveness question, Moschetti and his colleagues used incremental cost effectiveness as their primary outcome, with a willingness-to-pay threshold of $100,000/quality-adjusted life years (QALY).

“The results of our model suggest that the cost-effectiveness of next generation sequencing to diagnose PJI depends primarily on the pretest probability of PJI and the performance characteristics of the sequencing technology.”

“So, if you think the joint might be infected, using sequencing is cost effective. For a patient with a low pretest probability of infection, sequencing is not as valuable as the potential for false positive results exists. Our results are consistent with the idea that sequencing should be reserved for clinical contexts with a high pretest probability of PJI.”

“Next-generation sequencing may be used as part of a clinicians’ armamentarium for diagnosing PJI but should not be used in isolation. We should continue to rely on the MSIS criteria for diagnosis PJI but in cases where the pretest probability is high, sequencing can provide value. This may be most helpful in culture negative infections using traditional culture-based techniques, yet further study is warranted to help determine the appropriate indications for use.”

“The use of NGS may provide an improvement in diagnosing infection. Our analysis revealed that the pretest probability and test performance parameters of the NGS (sensitivity and specificity) were the largest factors for identifying whether a particular strategy was cost-effective. This technology does in fact seem cost effective for patients with a high pretest probability of infection and should be used cautiously on everyone, especially those with a low clinical suspicion of infection. Further study is needed to help guide clinicians on indications for the use of NGS and how to use NGS results to guide treatment.”