Outcomes of TB contact tracing and predictors of success: a 10-year retrospective cohort analysis in Birmingham, UK

BACKGROUND: Contacts of TB cases in Birmingham and Solihull, UK, are offered screening for TB infection. Between 1990 and 2010, only 59.1% of contacts completed screening. The service has since increased screening staff numbers, changed screening locations and increased screening follow-up. Our primary aim was to identify whether screening completion rates have improved. Our secondary aim was to identify predictors of screening completion. METHODS: This was a retrospective analysis of all contacts of TB patients in Birmingham and Solihull between 1 January 2011 and 31 December 2020, stratified by pulmonary and extrapulmonary TB (PTB or EPTB) index infection. Multiple logistic regression analysis for predictors of screening completion was performed. RESULTS: A total of 3,255 index cases and 27,820 contacts were identified. TB incidence has declined, in keeping with national trends. Screening completion has improved from 59.1% of contacts to 74.9% overall since service improvements were made, with improvement in screening completion for contacts of both PTB and EPTB index cases (OR 1.087, 95% CI 1.074–1.101; P < 0.001) and (OR 1.048, 95% CI 1.019–1.078; P = 0.001), respectively. CONCLUSIONS: Changes made to the TB service have improved screening outcomes over the last decade. Significant predictors of screening completion have been identified, highlighting areas for targeted resource allocation.