Losses in the Care Cascade for Latent Tuberculosis Infection in the Tracing Contact Studies

Background: The control of latent tuberculosis infection (LTBI) encompasses multiple stages. The objective was to calculate the losses in the LTBI care cascade for pulmonary TB contacts in Catalonia (Spain). Methods: The LTBI care cascade was studied for pulmonary TB contacts reported from 1 January 2019 to 30 June 2021, considering three dependent variables: non-performance of testing; non-receipt of a treatment prescription; and non-adherence to treatment. Variables associated with the cascade were analysed using adjusted OR (aOR) and 95% confidence intervals (CI). Results: Identified from 847 cases of pulmonary TB were 7087 contacts, of whom 6537 (92.2%) could be screened for LTBI. LTBI prevalence was 25.5% (1670/6537); 69.4% of persons with LTBI (1159/1670) received a treatment prescription and 71.3% (827/1159) completed it. Treatment prescription was associated with age >= 65 years (aOR = 0.3; 95%CI: 0.2-0.6) and a daily exposure of >= 6 h to the TB index case (aOR = 3.6; 95%CI: 2.6-5.0). Treatment adherence was lower in men (aOR = 0.7; 95%CI: 0.5-1.0) and immigrants (aOR = 0.7; 95%CI: 0.5-0.9). Conclusions: Under 50% of contacts make it to the end of the LTBI cascade. Losses need to be reduced through education of both healthcare providers and patients and through treatment monitoring. The greater involvement of primary care physicians could help in monitoring and controling LTBI.