TB infection in the incarcerated population of Catalonia, Spain

<sec><title>OBJECTIVE</title>To determine the prevalence of TB infection (TBI) among individuals admitted to Catalan prisons and assess the concordance between the tuberculin skin test (TST) and interferon-gamma release assays (IGRAs).</sec><sec><title>METHODS</title>A prospective, multicentre, population-based observational study was conducted in all nine Catalan prisons from 1 March to 30 June 2023. New admissions were classified based on history of TB or tuberculin testing. TBI was defined using TST thresholds adjusted for immunosuppression or Bacillus Calmette-Guérin vaccination. IGRAs were used in TST-positive or immunocompromised individuals. Logistic regression identified associated factors, and TST-IGRA concordance was assessed with the Kappa coefficient.</sec><sec><title>RESULTS</title>Among 1,679 participants, 38 (2.3%) had prior TB. Mean age was 38 years; 93.5% were male, 64.1% foreign-born, 23.2% homeless, and 3.4% living with HIV. TBI was found in 494 individuals (30.1%), and one case of active TB was detected. TBI was associated with older age, male sex (odds ratio [OR]: 2.05), foreign origin (OR: 3.92), injecting drug use (OR: 1.39), and smoking (OR: 2.06). TST-IGRA concordance was 64.5%. Prevalence adjusted for discordance was 25.2%.</sec><sec><title>CONCLUSION</title>TBI prevalence in Catalan prisons is high. Given the moderate agreement between TST and IGRA, relying solely on TST may be insufficient. Improved screening and treatment are essential for TB control in prison populations.</sec>.