Researchers looking for a better way to diagnose drug-induced liver injury (DILI) have found evidence to support the use of the Revised Electronic Causality Assessment Method (RECAM).
The broadly used Roussel Uclaf Causality Assessment Method (RUCAM), introduced in 1993, “has been a valuable clinical framework for DILI diagnosis,” but it has been clouded by subjectivity and poor reliability, wrote the authors, led by Paul H. Hayashi, MD, MPH, with the Food and Drug Administration, in Hepatology. Citing a review from the Journal of Hepatology, Dr. Hayashi and colleagues noted three major problems: “(1) unclear operating instructions and subjectivity leading to poor reliability and usability, (2) unclear validity due to lack of an accepted gold standard and (3) domain criteria that are not evidence-based.”
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Currently, a diagnosis of DILI is primarily based on clinicians’ judgment and ruling out alternative diagnoses, the authors of this study wrote. The lack of an evidence-based and reliable diagnostic tool is a significant obstacle in clinical care and research .
Reaching a new method
The researchers used classification tree analysis to set diagnostic cut-offs for RECAM and then compared RECAM with RUCAM for correlation with expert opinion diagnostic categories in 194 DILI cases (98 from the Drug-Induced Liver Injury Network, 96 from the Spanish DILI Registry).
The area under receiver operator curves for identifying at least probable DILI were the same at 0.89 for both RECAM and RUCAM.
The authors wrote, “However, RECAM diagnostic categories have better observed overall agreement with expert opinion (0.62 vs. 0.56 weighted kappa, P = .14), and had better sensitivity to detect extreme diagnostic categories (73 vs. 54 for highly likely or high probable, P = .02; 65 vs. 48 for unlikely/excluded, P = .08) than RUCAM diagnostic categories.”
They concluded that RECAM “is at least as capable as RUCAM in diagnosing DILI compared to expert opinion but is better than RUCAM at the diagnostic extremes.”
RECAM appears to add objectivity and clarity that can improve precision and reliability when diagnosing DILI and improve diagnostic standardization, according to authors. It has automated scoring, which reduces subjective input and should lead to better reliability among raters, something that has limited RUCAM’s adaptation in clinical practice and research.
RECAM has automatic warnings for data inconsistencies, which DILI and RUCAM do not. In RUCAM, a different diagnosis or other data could rule out DILI, but the case would still gain points in other criteria.
The authors explained, “Even when data clearly diagnose acute viral hepatitis or autoimmune hepatitis by simplified autoimmune hepatitis score, points are still given for latency, dechallenge, or underlying hepatotoxicity risk of the drug. In these situations of highly implausible DILI, RECAM gives warnings to stop with an imputed total score of –6. One can over-ride these warnings, if one believes DILI may be concurrent with the non-DILI diagnosis. However, –6 points are still assessed.”
Diagnosis of exclusion
Paul Martin, MD, chief, division of digestive health and liver diseases, Mandel Chair in Gastroenterology and professor of medicine at the University of Miami, said in an interview that he hopes RECAM will become widely used and better address a condition that sometimes doesn’t get enough attention. DILI remains underappreciated, he said, despite it being a major cause of morbidity and mortality in some patients.
Dr. Paul Martin
“Any algorithm or criteria that can improve diagnostic accuracy is useful because typically it is a diagnosis of exclusion,” Dr. Martin said. “This new system seems to be as good as any other prior algorithms to diagnose drug-induced liver injury.”
He added, “This should help clinicians with individual patients with unexplained liver disease.”
The authors noted some limitations. RECAM was developed in U.S. and Spanish cohorts, so its performance in other regions is unclear. Both registries have minimum enrollment requirements for liver enzyme and bilirubin elevation, so it is not known how effective RECAM is in less severe cases. It also needs to be tested by other clinicians, including nonhepatologists.
The authors also added, “It is currently limited to single-agent medication cases leaving the user to score each medication individually in multidrug cases. However, any competing medication causing loss of points in the RUCAM, probably deserves its own RECAM score.”
The DILIN is structured as a cooperative agreement with funds provided by the National Institute of Diabetes and Digestive and Kidney Diseases.
Dr. Hayashi is employed by the FDA, but the conclusions of this paper do not reflect any opinion of the FDA. One coauthor has advised Pfizer, GSK, and NuCANA through Nottingham University Consultants, and another has received support from Gilead and AbbVie and consulted for Sanofi. The remaining authors have no conflicts. Dr. Martin reports no relevant financial relationships.