Abstract Background/Aims Antinuclear antibody (ANA) testing is commonly used in the investigation of suspected connective tissue diseases (CTDs), despite limitations in both sensitivity and specificity. Positive ANA results are also frequently observed in other autoimmune conditions, infections, malignancies, and even healthy individuals. In community practice, ANA testing is often requested without appropriate clinical suspicion, contributing to diagnostic uncertainty, patient anxiety, unnecessary specialist referrals, and additional investigations. This audit aimed to evaluate the diagnostic relevance and clinical impact of ANA testing in community settings, with a focus on the appropriateness of its use and implications for patient management. Methods This retrospective audit included all ANA tests requested in community settings across the West of Scotland from June 2022 to October 2022. ANA testing was performed using indirect immunofluorescence on HEp-2 cells at the Queen Elizabeth University Hospital, Immunology Lab. Data were gathered on ANA test results, referral pathways, and the proportion of patients ultimately diagnosed with a connective tissue disease (CTD). Outcomes assessed included the rate of positive ANA results, rates of specialist referral, CTD diagnoses made, and implications for patient management. Results A total of 3,048 ANA tests were performed in the community during the audit period, of which 605 (19.67%) were positive. Among those with positive results, 190 patients (31.57%) were referred for further evaluation, either through outpatient clinics (19.50%) or via letter-based advice (10.41%). The majority of patients (68.43%) were not referred for specialist input. New diagnoses of CTD were established in 38 patients (6.7% of those tested). The most frequent titre pattern among positive ANA results was 1/80 homogeneous, accounting for 314 cases (51.9% of positive tests). The predominance of low-positive titres (particularly 1/80 homogeneous) suggests a high proportion of potentially clinically insignificant results in the absence of appropriate pre-test clinical suspicion. This highlights a low diagnostic yield from ANA testing in the absence of clear clinical suspicion. Conclusion A significant number of patients undergo follow up adding pressure on outpatient clinics for results that are often clinically insignificant. The cost incurred from the samples sent was approximately £41,393 (ANA costs £11 pounds and further titre for positive sample costs additional £13). This audit highlights that ANA testing in community practice has a low diagnostic yield for connective tissue diseases when performed without appropriate clinical indications. The findings support the implementation of clearer testing guidelines and targeted education for primary care clinicians to ensure more judicious and clinically driven ANA requests. Such measures could improve diagnostic efficiency, reduce unnecessary referrals, and minimise patient anxiety associated with indiscriminate positive results. Disclosure H. Choudhry: None. J. Quinn Toye: None. S. Maunick: None. L. McGregor: None. L. McGeoch: None.
Choudhry et al. (Wed,) studied this question.