Frequency of repeat antinuclear antibody testing in Ontario: a population-based descriptive study

Abstract

aboratory testing is the highest-volume medical procedure, 1 and volumes are increasing annually. 2,3 It has been estimated that 20% of tests are ordered unnecessarily. 4,5 Misuse of laboratory tests is a major challenge affecting the sustainability of health care. 6,7 Improving the appropriateness of rheumatology laboratory testing is a priority of Choosing Wisely campaigns. 8,9 Concerns have been raised about the inappropriate use of antinuclear antibody (ANA) testing. Testing for ANA is indicated only if a patient's clinical history and physical examination show symptoms or signs suggestive of systemic lupus erythematosus, scleroderma, Sjögren syndrome, polymyositis or dermatomyositis. 10,11 The test has high sensitivity, and, thus, a positive test result can contribute to a diagnosis of these conditions. 12 However, it has low specificity, and ANA and can be seen in other conditions and in more than 20% of healthy people, 13 which makes interpretation of test results challenging. 12 Choosing Wisely Canada recommends that "ANA testing should not be used to screen subjects without specific symptoms or without a clinical evaluation that may lead to a diagnosis of systemic lupus or other connective tissue disease." 8 International recommendations strongly advise that "ANA testing is primarily intended for diagnostic purposes, and not for monitoring disease progression" owing to its limited value in monitoring disease activity. 14-17 Thus, it is not appropriate to repeat ANA following a positive test result. 7-9,16,18

Frequency of Repeating Antinuclear Antibody Testing: When Less Is More

“…Contrary to the above-mentioned studies [ 18 , 19 ], in our study, most ANA tests were often ordered by highly specialized specialists rather than family medicine doctors (in the study group, 49% of ordered ANA tests were by the internal medicine department vs. 12.52% for that by the family medicine department). The most common locations for ordering ANA tests were outpatient settings (67.7% of ordered ANA tests), followed by inpatient departments (21.4%), and emergencies came in last with 10.9% of the total ordered ANA tests.…”

“…The percentage was similar whether the patient had only one ANA test or the tests were repeated. These findings are in disagreement with the previously mentioned studies, as the majority of ANA tests were found to be negative rather than positive [ 18 , 19 ]. Such findings likely reflect the variability in the cut-off values used to define a positive test, which needs further assessment.…”

“…One of the studies was done in Ontario, Canada, and involved 587,357 ANA tests that were performed on 437,966 adult patients from 2008 to 2015 [ 18 ]. The researchers found that only 21.5% of ordered ANA tests were positive, and from 587,357 ANA tests, 28% (164,913 tests) were repeated, with almost half of the repeated (49%) reordered within a year from a previous test.…”

“…When, in 2012, the American Board of Internal Medicine Foundation launched the campaign Choosing Wisely®: Next Steps in Improving Healthcare Value to encourage delivering evidence-based medicine among specialties and reduce cost and harm associated with unnecessary and unsupported use of investigations and treatments, ANA testing appeared at the top of the five items on which rheumatologists internationally agreed their practices needed to be questioned [16,17]. Since then and all over the globe, multiple studies have been carried out to investigate the landscape of ANA testing: out of all ANA tests, how many are ordered appropriately; which specialties order most of the tests; how much unnecessary ANA tests represent of HCE; and what interventions can be used to reduce the inappropriate ordering of ANA tests [18][19][20].…”