A Bayesian Approach to Assessment of Adverse Drug Reactions: Evaluation of a Case of Acute Renal Failure

Abstract

We evaluated a published case of suspected nephrotoxicity due to gentamicin using the Bayesian approach. The posterior odds (158.7) and probability (.99) were overwhelmingly in favor of drug causation. The major factors that drove the assessment were evidence from the patient's history prior to the onset of renal failure (he received an overdose and there were no findings to suggest another cause), the timing of the renal failure (14 days after gentamicin was started), and its characteristics (compatible with acute tubular necrosis). Although agreeing with intuitive judgment, the assessment differed from it in two crucial ways: (1) the result achieved was far more in favor of drug causation; and (2) the reasons for this assessment (both the evidence used and how it was combined) were precisely delineated. The case illustrates how the Bayesian approach to causality assessment deals effectively with the multiple uncertainties of even a relatively straightforward clinical case of suspected adverse drug reaction — a feat that we believe is beyond the scope of unstructured clinical judgment.