The Cohen Kappa of the Liverpool and the Naranjo Adverse Drug Reaction Causality Assessment Tool on Nervous System Drugs

Objective: Monitoring of side effects is essential to prevent and overcome the occurrence of drug side effects. Drugs that act on the nervous system have many similar side effects. One method of identifying side effect causality is using the Naranjo algorithm. Currently, there is a Liverpool algorithm, a refinement of Naranjo. This study aims to compare the Naranjo algorithm and the Liverpool algorithm in identifying the causality of side effects of drugs that act on the nervous system. Methods: This research is an observational study with a longitudinal method. Data collection was carried out prospectively in patients who were prescribed anticonvulsants, antidepressants, or antipsychotics. Four researchers will observe patients for three months. Adverse events were reported and tested using the Naranjo algorithm by two researchers and the Liverpool algorithm by two researchers. The measurement results of the two algorithms were tested with the Inter-Rater Reliability (IRR) by looking at the Cohen Kappa (K) agreement coefficient value. Result: The study involved 133 patients. Of the 133 patients, 74 (55.64%) experienced side effects with probable and possible causality. The kappa value for Naranjo is 0.465 (“moderate” IRR). It is 0.352 (“fair” IRR) for Liverpool, indicating that the researchers’ agreement was better on the Naranjo algorithm than the Liverpool algorithm. Conclusion: This study concludes that the Naranjo algorithm gives a higher kappa value than the Liverpool algorithm. Research using the Liverpool algorithm needs to be carried out by other researchers in Indonesia to find out the possibility of its use in clinical practice.