Cohort study of 1,616 TST/IGRA-positive contacts of pulmonary TB index cases diagnosed 2019–2021 in Catalonia, Spain, followed through 2023 (median 3.6 years) to estimate TB incidence and identify predictors of progression to active disease.
69 contacts (4.3%) developed TB at an incidence rate of 1,370/100,000 person-years. Strongest risk factors: age <5 years (aHR 25.0; 95% CI 11–59), not initiating TB infection (TBI) treatment (aHR 7.0; 95% CI 3.3–14.6), household contact (aHR 3.2; 95% CI 1.6–6.5), and smoking (aHR 2.8; 95% CI 1.7–4.6). Etiologic fraction of risk was 81.4%; completing TBI treatment was strongly protective.
Single-region observational design (Catalonia) limits generalizability. Residual confounding possible, as TBI treatment uptake and adherence were not randomized. Follow-up ended in 2023, so late progressors may be missed.
Prioritize prompt TBI treatment and support full adherence—especially in household contacts and children under 5—where the risk of progression is highest. Smoking status should be assessed and factored into risk stratification during contact tracing.
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