The uptake of tuberculosis preventive therapy in primary care: Current trends, facilitators, and barriers

Background: Tuberculosis (TB) is the leading cause of death from an infectious disease, with over 10 million new cases and over one million deaths annually. TB preventive treatment (TPT) reduces progression from TB infection (TBI) to disease, yet global uptake and completion remain low. Primary care, with its continuity and patient trust, is a promising setting to improve TPT delivery.Objectives: This thesis examines the role of primary care in identifying and treating individuals eligible for TPT, focusing on the cascade of care for TB infection through global and local analyses.Methods: Project 1 was a mixed-methods systematic review of the cascade of care in primary vs non-primary care, including quantitative and qualitative studies from four databases. Data were stratified by country income and categorised into identification, testing, treatment initiation, and completion. Quantitative data were analysed with random-effects meta-analysis; qualitative findings underwent content analysis; integration was done via joint displays.Project 2 was a retrospective chart review of persons in whom TBI screening was recommended. It was done at a primary care clinic in Montreal serving predominantly foreign-born patients. The cascade was reconstructed from electronic records; logistic regression evaluated patient characteristics associated with testing.Results: Project 1: Of 6966 records, 162 studies were included. In primary care in high-income countries (HIC), 48.7% of eligible patients were identified, 92.4% received results, 33.8% of people with positive tests started TPT, and 78.1% completed treatment, for a cumulative completion of 11.9%. In low- and middle-income countries (LMIC), 72.3% of the eligible patients were identified, 98.4% had results, 53.9% started TPT, and 65.7% completed it, with 25.2% cumulative completion. Completion once treatment began was similar to non-primary care. Qualitative findings identified structural/clinic, patient/caregiver, provider, and test/treatment-related barriers and facilitators.Project 2: Among 677 charts, 200 patients were considered eligible to TBI screening (mean age 36.1 ± 17.2; 70% female). Only 48 (24%) had a tuberculin skin test (TST) ordered, 31 (15.5%) had results, and 17 (54%) were positive. Of the 186 TPT-eligible individuals, 16 (8%) were referred for TB disease evaluation, 15 (7.5%) completed it, 8 (4%) were diagnosed with TBI, and all received TPT. Completion was documented for only 3 (1.5%). Having the first contact at the clinic for perinatal care was significantly associated with lower odds of TBI testing among women (OR = 0.063; 95% CI: 0.014–0.281). Conclusion: Primary care is central to screening and preventive health; however, substantial losses in the TB cascade occur early during the identification of eligible patients and treatment initiation, as consistently demonstrated in our systematic review and cohort project. The more diverse the services delivered in a primary care setting and the lower the prevalence of TB in the population served, the greater the likelihood that TB infection testing and treatment will be overlooked. Identifying opportunities to target populations at risk and addressing structural, provider, patient, and treatment-related barriers is crucial to improving retention and expanding TB prevention efforts