False positive results for rheumatoid arthritis (RA)—a common result in serological testing—add therapeutic complexity as well as economic cost that could be reduced by simultaneous multi-analyte tests. Multiple tests could confirm a diagnosis, prevent over- or under-treatment of patients, and reduce expenses across the care spectrum.
In an analysis presented to the American College of Rheumatology, Teresa Tarrant, MD, a Duke rheumatologist and immunologist, outlined the need for additional research to better understand the ways in which imprecise diagnostic testing “contributes to the economic burden of RA,” she says.
Approximately 1.3 million individuals in the United States are affected by RA; the financial impact of the disease exceeds $19.3 billion. The authors of the analysis suggest that the true cost of diagnosis and testing are not well understood. “Frankly, it’s an unexplored topic that deserves a great deal more attention,” Tarrant says.
Cyclic citrullinated peptide (CCP)laboratory testing is typically more accurate for rheumatoid arthritis than the older rheumatoid factor (RF) test. But as a stand-alone diagnostic, Tarrant cautions, the test is not perfect. As a result, the authors raised questions about the consequences of CCP false positive (CCP-FP) or CCP-false negative (CCP-FN) results within the larger health care delivery system.
The study included an economic simulation that used inaccurate diagnostic rates and previously published financial data to estimate unnecessary costs generated from testing that fell outside normal range. The simulated costs varied significantly based on the type of test used.
In clinical practice, Tarrant says, physicians consider it beneficial to test for both RF and anti-CCP results rather than test for each antibody individually. To increase diagnostic accuracy and to reduce the time necessary to diagnose the condition, both RF and anti-CCP markers should be measured in tandem, she suggests. The results from these multi-analyte tests are considered complementary, especially in early stages of the disease, Tarrant says.
“What are the downstream costs of a misclassification of RA?” asks Tarrant. “If we have a misclassification, what is the economic impact of reversing that diagnosis and assigning a new therapy to address the condition? And what about the patient who must be “un-diagnosed”? Patients are required to undergo additional tests and make more visits to specialists. Physicians must also duplicate previous efforts to correct the diagnosis and reassure the patient.
“It’s clear that simultaneous multi-analyte testing is more effective than testing for individual rheumatoid factors (RF IgA or RF IgM) or CCP as stand-alone testing,” she says. “This approach may prevent incorrect diagnoses and more appropriate subspecialty referral for definitive treatment.”