Prevalence and associated risk factors of latent tuberculosis infection in a Spanish prison.

Aim: To determine the prevalence of latent tuberculosis infection (LTI) in a Spanish prison, analyze the main sociodemographic and clinical variables associated with this condition and estimate the percentage of individuals with LTI who have received chemoprophylactic treatment.

Materials and methods: Cross-sectional study including inmates hosted in the Madrid VI Prison on 16/07/2016. Exclusion criteria: history of tuberculosis; non-updated tuberculin test according to the Tuberculosis Prevention and Control Program in Prisons protocol. Information of the variables was collected from SANIT and SIP programs, and by checking the clinical records of inmates. Description of the participant population and comparison between the frequency of distribution of the independent variables in LTI present and absent groups were performed, the last calculating the p value with Ji2 and Mann-Whitney U tests. Bivariate and multivariate analysis have been carried out with a logistic regression model.

Results: 936 individuals have been included. The prevalence of LTI in prison is 54.6%. This condition has been linked to the sociodemographic variables age, sex and nationality of origin, being age the one that has shown the strongest association. Among the other factors analyzed, only HCV infection behaves as a predictor of LTI. 30.3% of the individuals with LTI have completed or are receiving chemoprophylactic treatment in the moment of the study.

Discussion: LTI prevalence is high in the Spanish current prison population. The results of the study emphasize the relevance of the LTI screening in the prison setting, specially among high risk groups, and point out the need of a greater effort in the indication and completion of the chemoprophylactic treatment.