Repeated ANA testing costly and has low utility, says Lancet study
Australia: There is a little benefit in repeating antinuclear antibody (ANA) testing after it has yielded a negative result in the first place, suggests a recent study in The Lancet Rheumatology journal. According to the study, repeat ANA testing after a negative result has low utility and results in high cost.
ANA testing is used frequently as a diagnostic or screening test in patients having musculoskeletal or inflammatory symptoms. The value of repeat is unclear. Ai Li Yeo, Centre for Inflammatory Diseases, Monash University, Clayton, VIC, Australia, and colleagues sought to evaluate the frequency, utility, and cost of repeat ANA testing. They assessed the positive predictive value of a repeat ANA test for the diagnosis of rheumatological conditions associated with ANA.
The researchers analyzed data from a single multisite tertiary health network in Australia across a 7-year period in this retrospective cohort study. The results of ANA and other autoimmune test were obtained from the hospital pathology system with a positive ANA titre cutoff set at 1:160. Clinical information was obtained from clinical information systems on any patient who had a change in ANA result from negative to positive on repeat testing. The cost of repeated ANA testing was calculated using the Australian Government Medicare Benefits Schedule.
From March 19, 2011, to July 23, 2018, a total of 36 715 ANA tests were done in 28 840 patients at a total cost of US$675 029 (2018 equivalent).
Key findings of the study include:
- 14 058 (38·3%) of these ANA tests were positive.
- 7875 (21·4%) of the ordered tests were repeats in 4887 (16·9%) of the patients, among whom 2683 (54·9%) had initially negative tests, and 2204 (45·1%) had initially positive tests. 511 (19·0%) of the 2683 patients with initially negative tests had a positive result on at least one repeat test, with a median time to first positive result of 1·74 years (IQR 0·54–3·60).
"Repeat ANA testing after a negative result has low utility and results in high cost," wrote the authors.
The study, "Utility of repeated antinuclear antibody tests: a retrospective database study," is published in The Lancet Rheumatology.