PS1:7 Antinuclear antibody (ana) and antineutrophil cytoplasmic antibody testing in a tertiary health entre in sherbrooke: an assessment of the adherence to the guidelines and the impacts on the diagnosis and health care system

Abstract

Objectives To describe antinuclear antibodies (ANA) and subserology ordering practices and to determine if its’ indications meet the recommendations for ANA testing at the Sherbrooke University Health Centre, in Canada. To describe antineutrophil cytoplasmic antibodies (ANCA) practices and determine if they meet the 1999 guidelines proposed for ANCA testing, at the same centre. Methods We identified the indications for the ANA and subserologies panel (Anti-SSA, anti-SSB, Anti-Jo1, Anti-Scl-70, Anti-Sm, Anti-U1 RNP) between 2012 and 2014 and compared to the guidelines for ANA testing. Moreover, the indications for ANCA tests were assessed and compared to the 1999 guidelines for the appropriate testing of ANCA.Variables included gender, age, ANA titer, subserologies panel, indication of ANA, ANCA, subtypes MPO and PR3, indication for ANCA, medical specialty, setting of the order and the final diagnosis. Results There were a total of 268 ANA tests included. In 35.8% of cases (n=96), ANA was ordered as per recommandations versus 63.8% of cases (n=171) without indications. There were 104 subserologies ordered and 55.8% were ordered at the same time as the ANA, against the Choosing Wisely recommendation of 2013. There were only 22% of ANA that were required for a diagnosis. The 3 specilaties who ordered ANA the most were rheumatology, gastroenterology and the internal medicine (in descending order). The cost for the ANA that were not indicated is more than a thousand dollars. A total of 135 ANCA tests were included. There were 55.6% of ANCA that were ordered in line with the recommandations. However, 50.3% of ANCA were not required for the final diagnosis. Clinical remission of subjects with ANCA was predicted in 100% of cases, even before ordering the ANCA test for follow-up (negative predictive value). Conclusion These results show that the rate of ANA and ANCA tests ordered in line with the recommandations remains low. In the majority of cases, the two antibodies are not required for the final diagnosis. These orders have an important cost for the hospital that can be lowered by providing more education for professionals on avoiding unnecessary tests.