Ab1620-HPR Change in the Utility of Antinuclear Antibodies (Ana) Following the Implementation of Analytical Request Based on Patient Profile

Background: The diagnosis of autoimmune diseases has increased, reflected in a rise in the number of ANA determinations per year and referrals to the rheumatology service (RS) for the assessment of positive results. It was estimated that 70% of diagnoses are based on laboratory tests, but if the indication for ANA corresponds to a reasonable pretest probability, the likelihood of obtaining valuable post-test information increases, and vice versa. The indiscriminate request for ANA leads to system overload and increased expenses, undermining the value of the results. Objectives: To compare the employability and cost of ANA determinations before and after the implementation of a tool for requesting analyses based on the patient's clinical profile in Primary Care (PC). Methods: Retrospective, longitudinal study where two study periods are established: the year 2021 (24-month follow-up) and the year 2023 (follow-up for the year 2023). The following data are collected: number of ANA requests from PC, number of referrals to RS due to positive results, patient profile, clinical manifestations for which tests are requested, final diagnosis, discharges, and follow-up time. The expenditure on ANA determinations, the appropriateness of the request in referred patients, and the changes in these parameters before and after the tool's implementation in 2022 are analyzed. Results: There is an upward trend in the number of ANA requests from PC from 2019 to 2021, with a rising expenditure trend of 2.28%. Subsequently, this trend is reversed (Table 1), calculating a savings, solely in ANA determinations, of 36,120.96 euros in 2022 and 2023. In 2021, 134 patients were referred to RS due to positive ANA, at a time when there were 3 rheumatologists, and 123 in 2023, when there were 5, showing a decrease in the referral rate to rheumatologists, being 44.6 in 2021 and 24.6 in 2023. Table 2 presents the comparison of variables from patients referred to RS in both periods. Conclusion: The new tool has facilitated a reduction in expenses for ANA determinations and referrals to the RS, and improving pretest appropriateness for those referred to the RS. In 2023, the diagnosis of rheumatoid arthritis, other types of arthritis, and polymyalgia rheumatica decreased, aligning with three of the clinical profiles defined by the tool and adjusting suspicion-determination. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.