Background/Purpose:

Anti-citrullinated peptide antibodies (ACPA) are more specific and have a superior positive predictive value for diagnosis of rheumatoid arthritis (RA) compared to RF. The American College of Rheumatology revised the RA classification criteria to include ACPA in addition to RF in 2010 (Arthr Rheum. 2010; 62:2569-2581). This study’s aim is to characterize utilization of RF and ACPA among primary care, non-rheumatology subspecialty, and rheumatology providers 2 years before and 2 years after the new criteria were published. The expectation is that the 2 tests will be ordered in a 1:1 ratio after the new criteria, whereas RF would be ordered more than ACPA before 2010. 

Methods:

The study was performed at an academic medical center in the western United States. All orders for RF and ACPA (ordered as anti-CCP) placed in 2008 and 2012 were retrieved and the medical records from outpatient encounters were reviewed. Orders meeting the following criteria were included: (1) RA was in the differential diagnosis, (2) patient endorsed musculoskeletal complaints, and/or (3) the provider noted tests were ordered for an “inflammatory,” “rheumatologic,” or “autoimmune” indication. Orders placed on patients with a previous history of RA or who were being evaluated only for extra-articular manifestations of RA or cryoglobulinemia were excluded. Included orders were sorted by provider type (primary care, non-rheumatology subspecialty, rheumatology), and the ratio of RF to anti-CCP orders for each type was calculated. 

Results:

Out of 765 RF & antiCCP orders reviewed, 463 orders (238 from 2008 and 225 from 2012) met the inclusion criteria. Of these, 297 (64%) were ordered by primary care providers, 80 (17%) by non-rheumatology subspecialty providers, and 86 (17%) by rheumatology providers. The RF/anti-CCP ratios by provider type comparing 2008 to 2012 were as follows: primary care providers 2.7 vs. 3.1, non-rheumatology subspecialty providers 12.5 vs. 3.5, and rheumatologists 0.85 vs. 0.96. Isolated RF orders represented the majority of orders placed by non-rheumatologists (primary care and subspecialty providers) comprising 72% and 70% of total orders placed in 2008 and 2012, respectively. Among rheumatologists, RF in isolation represented only 4% and 11% of orders, while the combination of RF and anti-CCP comprised 66% and 88% of orders placed in 2008 and 2012, respectively. 

Conclusion:

Our results indicate that 2 years after revision of the RA classification criteria, anti-CCP remains a vastly underutilized test among non-rheumatology providers considering the diagnosis of RA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ordering-of-serologic-markers-of-rheumatoid-arthritis-among-primary-care-and-subspecialty-providers-under-utilization-of-anti-citrullinated-peptide-antibody-tests-by-non-rheumatologists/