Background Reactivation of latent tuberculosis infection (LTBI) occurs in a number of at-risk groups including: tuberculosis (TB) contacts, migrants from high prevalence countries and those who are immunosuppressed. The risk of hepatotoxicity in treating LTBI is thought to be low but much of this evidence is in patients treated with 6 months of isoniazid (6H) rather than 3 months of rifampicin and isoniazid (3RH). Equally, other than age, there is limited data on other factors which may contribute to the risk of developing hepatotoxicity.
Methods A retrospective study was performed at our centre. We analysed all patients treated with chemoprophylaxis, regardless of indication, between 2009 and 2013. Demographic data, treatment regimens and adverse drug reactions, including hepatotoxicity, were recorded. Severe hepatotoxicity was defined as either a rise in ALT five times greater than the upper limit of normal, or as any change in liver function that required an interruption or alteration in treatment. Liver function tests (LFTs) were routinely measured at baseline and then again at two weeks.
Results 290 cases were identified. 84.5% of patients were treated with 3RH, 12.1% were treated with 6H. 2.1% experienced severe hepatotoxicity 2 weeks into treatment. None had symptoms which prompted blood tests prior to our standard 2 week LFTs. Gender, age, documented co-existing liver disease, regimen choice, concomitant use of hepatotoxic drugs and reason for giving chemoprophylaxis were not significantly associated with an increased risk of hepatotoxicity. LTBI treatment was case managed by TB nurses with 91.7% of patients successfully completing treatment. There was no significant difference in treatment completion or adherence rates in those who developed hepatotoxicity compared with those who did not.
Conclusions Our review demonstrates a low incidence of hepatotoxicity associated with treatment of LTBI and highlights the difficulty in predicting those in whom it will occur. If management of LTBI moves from primary to secondary care it will remain important to perform LFTs at two weeks.