P231 The TBC3 study: a mixed methods investigation of the factors that influence successful tuberculosis contact tracing in low prevalence settings

<h3>Background</h3> Identifying and treating infected contacts of infectious tuberculosis is central to global tuberculosis control. Developing and implementing national contact tracing evidence-based guidance is a key priority in the UKHSA Tuberculosis action plan for England, 2021–2026.¹ We conducted a mixed methods study to investigate factors influencing progression along the contact tracing cascade across the four TB services in South Yorkshire to identify barriers that might be effectively addressed by intervention in low-incidence settings such as England. <h3>Methods</h3> We extracted and analysed 2018–2023 data from the National Tuberculosis Surveillance System (NTBS) to establish timings and proportions of index case contacts’ progression through the cascade and identify index case factors predictive of progression. We conducted semi-structured interviews with service users and providers then used thematic analysis to draw out barriers and facilitators to contact cascade progression. We then discussed these results with a provider focus group to further explore which factors could be amenable to intervention. <h3>Results</h3> 1044 contacts were identified for 258 index cases; 22.9% were never screened, and 25.5% of those with latent TB infection did not complete treatment. Index case factors predictive of successful contact identification were high infectivity, Pakistani ethnicity, and Central/Eastern European birth. Contacts were less likely to progress if the index case was of non-white ethnicity or resided in a higher deprivation area. Differences between services were also observed. 4 major themes, encompassing 23 subthemes, emerged from 18 interviews (figure 1). The focus group corroborated these themes. Crucially, the group identified where factors were specific to particular services (communication method, screening procedure) or populations (community-specific illness behaviours, health literacy) and thus might yield best-targeted rather than across-the-board interventions. <h3>Conclusion</h3> We have identified patient and service factors affecting contact tracing that could be amenable to targeted intervention and are likely to be generalisable to similar settings. Informed by these findings, we will conduct a broader questionnaire survey of index cases and their contacts, e.g. to include individuals who declined screening, to substantiate and add to our findings. <h3>Reference</h3> UKHSA,2021&lt;https://www.gov.uk/government/publications/tuberculosis-tb-action-plan-for-england/tuberculosis-tb-action-plan-for-england-2021-to-2026&gt;