Hepatic adverse drug reactions: a case/non-case study in Italy

OBJECTIVE: Adverse drug reactions (ADRs) can involve all tissues and organs. Liver injuries are considered among the most serious and are a cause for concern among physicians and patients. To assess the extent of drug-induced liver injuries in Italy we compared the number of cases of hepatic ADRs with reports of all other drug-related reactions present in the same database. METHODS: Spontaneous reports from six Italian Regions collected from January 1990 to May 2005 were analysed. Adverse reactions were classified according to WHO Adverse Reaction Terminology for causality assessment, and only those with "certain", "probable" or "possible" causality assessment were included. Association between drugs and hepatic ADRs was assessed using the case/non case method, calculating the ADR reporting odds ratio (ROR) as a measure of disproportionality. RESULTS: On May 2005, the database contained 35,767 ADR reports, of which 11,829 were excluded because they were unclassifiable or unlikely in terms of causality assessment. Therefore, the analysis was carried out on 23,938 reports, of which 1,069 concerned hepatic ADRs (cases) and 22,869 concerned non-cases. The proportion of serious ADRs was about 40% in the overall database, and about 74% among cases. The drug classes with the highest number of cases were statins (ROR = 2.9, 95% CI 2.4-3.5), antiplatelet agents (ROR = 3.5; 95% CI 2.6-4.6), NSAIDs (ROR = 2.9; 95% CI 2.1-3.9) and macrolides (ROR = 1.7; 95% CI 1.2-2.3). CONCLUSION: Hepatic adverse drug reactions remain a serious concern for several drugs widely used in clinical practice. Monitoring hepatic enzymes on a monthly basis for the first 6 months of treatment has been suggested for patients taking medications known to be hepatotoxic. A better knowledge of the epidemiology and mechanisms of hepatic ADRs may contribute to minimising their occurrence.