Screening for Wilson's disease in acute liver failure: A comparison of currently available diagnostic tests

Abstract

The recently published article by Korman et al.1 suggests that the sequential use of two scores (alkaline phosphatase/total bilirubin ratio < 4 [94% sensitivity, 96% specificity] and aspartate aminotransferase/alanine aminotransferase ratio > 2.2 [94% sensitivity, 86% specificity]) in a population with acute liver failure can identify those with Wilson's disease with 100% sensitivity and 100% specificity. This is a statistical impossibility. Use of the first score will correctly identify 94% of patients with Wilson's disease and 96% of those without Wilson's disease. Applying the second score to the group with an alkaline phosphatase/total bilirubin ratio < 4 may improve the specificity, but the sensitivity (within the total population) cannot be greater than 94%. Applying the second score to that group with an alkaline phosphatase/total bilirubin ratio > 4 may improve the sensitivity, but the specificity (within the total population) cannot be greater than 86%. Applying the second score to both groups selected by the first score (i.e., the whole population) will result in 94% sensitivity and 86% specificity. Dr. Damian Dowling*, * Geelong Hospital, Geelong, Australia.