Preventive treatment of latent tuberculosis infection: prevalence of adverse events among 23602 patients treated over the last 30 years at Villa Marelli in Milan.

<b>Background:</b> Latent tuberculosis infection (LTBI) is a common finding requiring preventive treatment in certain conditions. Treatment can, however, be responsible for adverse events (AEs). <b>Aims:</b> Evaluate the prevalence and kinds of AEs in patients undergoing the three most commonly used treatment regimens. <b>Methods:</b> This single centre, retrospective, observational, cohort study enrolled patients affected by LTBI referring to Villa Marelli outpatient clinic from 1992 to 2022. Treatment regimen, reported AEs and blood tests results were collected before treatment and during follow-up visits. <b>Results:</b> A total of 23602 patients were treated for LTBI, of which 3413 (14.5 %) developed a relevant AE (see Table1.) <b>Table 1.</b> <b>Conclusions:</b> Gastrointestinal AEs were the most commonly reported in all of the three treatment regimens, followed by central nervous system AEs for isoniazid. Rifampicin alone was the most frequently linked to allergic reactions. All other reported AEs were less common.