Completion rates of LTBI treatment: shifting prescription from INH alone to RIF containing regimens. Observation from 1992 to 2017

From 1992 to 2017 our Centre prescribed 19746 LTBI preventive treatments (PT) for reasons including contact with Tb cases, immune suppression (HIV, anti-TNF etc), homeless applying to city shelters, health care worker, asylum seekers, untreated TB scars etc. Until 2010 INH alone was almost always prescribed except in contacts of INH-resistant cases, while RIF containing PT regimens progressively became a prevalent choice from 2011 on. Of the 18961 with complete records, 82,7% received isoniazid (INH) for 6 months, 15.4% combined rifampicin and isoniazid ( RIF+INH) for 3 months, and 1.9% RIF alone for 4 months. Italians were 27 %, 9.1% came from Eastern Europe, 19.7% from Latin America, 14.3% from Asia and 29.9% from Africa. All patients underwent HIV testing, and 0,5% were positive. Patients also received exhaustive explanations on the rationale of PT and possible adverse reactions, and 924 refused the treatment immediately. Tolerability was good, and definitive treatment termination due to SAE was reported in 2.6%, 0.6% and 2.6% of INH, RIF+INH and RIF only treated patients. Severe hepatitis was negligible, being reported in 53 (0,3%, as reported in literature) and in 1 and 1 patients, of the three groups. Overall completion rates were 77.5%, 84.9% and 81.5% for INH, RIF+INH, and RIF, with much lower scores in the 2882 homeless pts (51.4% INH, 78% RIF+INH). Lost to follow up were also high in this particular group (37.5% INH and 17.2% RIF+INH), mostly within the first 2 mo of treatment. A further shortening of PT regimens, such as the one with 1mo daily PH recently proposed, should be pursued.