RECAM‐J 2023—Validation and development of the Japanese version of RECAM for the diagnosis of drug‐induced liver injury

Aim The diagnosis of drug‐induced liver injury (DILI) is challenging. We modified the revised electronic version of the Roussel Uclaf Causality Assessment Method (RUCAM) for the diagnosis of DILI (RECAM), the scoring system developed in US and Spanish cohorts in 2022, and developed RECAM‐J 2023 to align with the clinical practice in Japan. In the current study, we introduce RECAM‐J 2023 and verify its performance in the context of Japanese patients with DILI. Methods After translation of RECAM into Japanese, modifications were made to develop RECAM‐J 2023 without any alteration to the scores. To examine the validity and performance of RECAM‐J 2023, clinical information on DILI and non‐DILI cases in Japan were retrospectively collected. The diagnosis of DILI was made by expert's decision. Then we scored each case using RECAM‐J 2023, and calculated area under curve (AUC) values for identification for DILI. Results We collected data from 538 DILI and 128 non‐DILI cases. The sum of highly probable (HP) and probable (PR) cases categorized by RECAM‐J 2023 were only 206 (38%) in DILI cases. As the primary cause of low scores was the deduction with missing hepatitis virus markers, which is unlikely to be an issue in prospective applications, we rescored without these deductions. At this time, the sum of HP and PR was raised to 421 (78%). The AUCs of RECAM‐J 2023 without deductions were 0.70 and 0.88 for identifying at least HP, and at least PR, respectively. Conclusion RECAM‐J 2023, when prospectively used without any missing hepatitis virus markers, provides acceptable performance for identifying at least PR DILI cases in Japanese daily clinical practice. Because liver damage occurring as an adverse effect of drugs is difficult to diagnose, scoring systems are used. We developed the RECAM‐J 2023, a Japanese version of the RECAM scoring system developed overseas, and validated its usefulness using data from 538 patients with drug‐induced liver injury and 128 patients with other liver disorders in Japan. The results showed that 78% of patients were diagnosed as highly probable or probable, indicating that RECAM‐J 2023 is useful in Japanese clinical practice.