To the Editor:

Rheumatoid arthritis (RA) is the most common inflammatory arthritis, and left untreated, can lead to irreversible joint or extraarticular damage.1 Patients with RA are diagnosed through a combination of clinical, radiographic, and laboratory findings, based on the 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria.1 Delays in diagnosing RA can lead to long-term damage and disability.

The antibodies involved in diagnosing RA are rheumatoid factor (RF) and anticyclic citrullinated protein (anti-CCP). Both serological markers are given the same weight in the classification criteria for RA1; however, RF has a sensitivity of 67% and specificity of 79% for RA,2 and can be positive in other conditions such as Sjögren syndrome, systemic lupus erythematosus, endocarditis, hepatitis C, and malignancies.2 Anti-CCP, on the other hand, has a 79% sensitivity and a 98% specificity,3 and is rarely positive in other conditions. Using anti-CCP and RF together can increase diagnostic accuracy of RA.

Since it is of the utmost importance to diagnose RA, patients with suspected RA should be seen quickly and have access to appropriate testing. Based on the Canadian Rheumatology Association wait time benchmarks, patients with suspected RA should be seen by a rheumatologist and RA should be confirmed within 4 weeks.4 This contrasts with a previous literature review that found the average patient with RA has a delay of 11.8 months from onset of symptoms to initiation of treatment.5 If a patient has signs or symptoms of RA and the clinical index of suspicion is high, this patient should have access to both RF and anti-CCP testing, to diagnose RA and initiate treatment in a timely manner.

Restricted ordering is a policy in which only certain groups or specialists can order a test to help reduce overuse and costs, as well as adverse effects associated with testing. Previously in Nova Scotia, ordering an anti-CCP test was restricted to rheumatologists; however, this restriction was removed in 2015. Increased availability of testing may reduce the delay in diagnosis, leading to improved quality of life and decreased risk of progressive destructive disease. This study retrospectively analyzed anti-CCP testing data, to identify if removing anti-CCP ordering restrictions impacted testing rates and the rate of positive tests.

In 2015, with removal of order restrictions, the number of anti-CCP tests ordered increased by 66% (2010-2014 vs 2015-2019), largely driven by nonrheumatologists, whose testing increased by 436% (Figure 1). In this same time frame, the number of positive anti-CCP tests did not change, whereas the number of negative anti-CCP tests increased by 191% (Figure 2). The rate rheumatologists ordered positive and negative tests was largely unchanged.

Number of anti-CCP tests ordered annually in Nova Scotia by rheumatologists and other providers from 2010 to 2019. Anti-CCP: anticyclic citrullinated protein.

Number of positive and negative anti-CCP tests in Nova Scotia annually from 2010 to 2019. Anti-CCP: anticyclic citrullinated protein.

Overtesting is an issue in health care; it is estimated that approximately 30% of tests are unnecessary.6 Any test has risks to the patient, including risk of infection, injury, patient anxiety, unnecessary referrals, and further testing.6 Choosing Wisely is a clinician-led campaign to facilitate discussions around overuse, waste, and harms of unnecessary testing in health care and provides lists of recommendations developed by national specialty associations to help guide clinical practice.7 The most recent iteration for rheumatology includes guidance around ordering anti-CCP only when patients have clinically suspicious arthralgias or arthritis on physical exam.8 Other interventions beyond guidelines, such as restricted ordering, requiring indications for testing to be performed, and prompts demonstrating costs associated with tests have all been used to try to reduce unnecessary testing.9

Despite methods to reduce tests that do not provide value to patient care, unnecessary testing still occurs. In 2017, a survey of primary care providers found that although Choosing Wisely recommendations were easy to follow, fears around malpractice, lack of time, and patient requests meant that many of the guidelines were not being followed.10 This may be a target for future interventions, and potentially a source of education for physicians. Despite open ordering of many tests such as anti-CCP becoming common, the present study shows that it does not lead to higher rates of positive tests. In fact, more negative tests and more testing overall would have led to higher healthcare expenditure and potentially more patient anxiety. Limitations of this study are that there is no linkage between the test that was ordered and whether it led to more referrals to rheumatologists; it is also unknown if there were duplicates of the test ordered on the same patient.

Access to testing is important for diagnosis, as early treatment can help reduce joint destruction. However, this study shows that more education on appropriate ordering is needed, because when restrictions were removed, more tests were being ordered. However, the rate of negative tests greatly outnumbered the rate of positive tests. There is the opportunity for interventions around the ordering of anti-CCP in the correct clinical context. Open ordering is beneficial to patients if they receive quicker diagnoses and care; however, one must be cautious in overordering tests as this also has harms.