Choosing wisely in daily practice: a mixed methods study on determinants of antinuclear antibody testing by rheumatologists

<p><b>Objectives</b>: To explore the relationship between antinuclear antibody (ANA) overuse and rheumatologist-related factors before and after an intervention aimed at reducing ANA overuse.</p> <p><b>Method</b>: In this mixed methods study we performed surveys among rheumatologists (n = 20) before and after the ANA intervention (education and feedback). We identified clinician-related determinants of ANA overuse (demographic characteristics, cognitive bias, numeracy, personality, thinking styles, and knowledge) by multivariate analysis. Two focus group meetings with rheumatologists were held 6 months after the intervention to explore self-reported determinants.</p> <p><b>Results</b>: Questionnaires were completed by all rheumatologists and eight participated in the focus groups. Rheumatologists with more work experience and a less extravert personality ordered more ANA tests before the intervention [β = 0.01, 95% confidence interval (CI) 0.003 to 0.02, p = 0.01 and β = −0.11, 95% CI −0.21 to −0.01, p = 0.04, respectively; R<sup>2</sup> = 47%]. After the intervention, female rheumatologists changed less than their male colleagues with regard to the number of ANA tests ordered (β = 0.15, 95% CI 0.03–0.26, p = 0.02; R<sup>2 =</sup> 25%). During the focus groups, seven themes were identified that influenced improvement in ANA overuse: determinants related to the intervention and the study, individual health professionals, patients, professional interactions, incentives and resources, capacity for organizational change, and social, political, and legal factors.</p> <p><b>Conclusions</b>: We identified several determinants that together explained a sizable part of the variance observed in the ANA outcomes at baseline and in the change in ANA outcomes afterwards. Furthermore, the focus groups yielded additional factors suggesting a complex interplay of determinants influencing rheumatologists’ ANA ordering behaviour.</p>