Characterizing phenotypes and outcomes of drug-associated liver injury using electronic medical record data.

PURPOSE: To evaluate the incidence, phenotypes, and outcomes of drug-associated liver injury identified in electronic medical record (EMR) data using standardized criteria for drug-induced liver injury (DILI).
METHODS: This retrospective cohort study used EMR data from a large integrated healthcare system. Study inclusion required 18 years of age or older, ≥1 prescription fill for any of 14 medications associated with hepatotoxicity between 1 January 2003 and 30 June 2009, and ≥12 months of membership prior to the drug exposure. Patients with underlying non-drug causes of liver injury were excluded to minimize capture of liver injury events unrelated to drugs. Drug-associated liver injuries were identified by liver chemistry elevations temporally associated with drug use based on standardized criteria for DILI. Cases were classified by clinical pattern and severity. Outcomes of liver transplant and all-cause and liver-related death were examined.
RESULTS: A total of 1 053 979 drug exposures were identified in 601 125 patients. We identified 265 drug-associated liver injuries (32.8 per 100 000 persons) occurring in 250 patients. Isoniazid exhibited the highest incidence rate of 606 per 100 000 persons. Of the 265 cases, 41% were mild; 12% exhibited moderate drug-associated liver injury (with concomitant ALT ≥ 5× ULN and bilirubin ≥2× ULN); and 17% exhibited coagulopathy, ascites, encephalopathy, or other organ failure. Last, seven cases (3%) were associated with death, and there were no liver transplants.
CONCLUSIONS: Study results align with earlier prospective studies, supporting the value of standardized methodology to identify drug-associated liver injury in the EMR. These methods can potentially enhance safety and clinical outcomes.