Interpretation of Diagnostic Tests: Likelihood Ratio vs. Predictive Value

We read with interest the iranikhah et al’s article entitled “stool antigen tests for the detection of helicobacter pylori in children” in the second issue of 2013 of iran j pediatr. the authors have well reported an interesting investigation about the detection of bacterial antigens in stool for diagnosis of helicobacter pylori in children. also they appropriately used endoscopy and biopsy as a gold standard test for validation of the h. pylori infection and statistical indices are calculated accordingly. in the study, sensitivity, specificity, positive and negative likelihood ratios for h. pylori stool antigen was reported to be 85%, 93%, 89.7%, and 90% respectively, while 89.7%, and 90% are not likelihood ratios, they are positive and negative predictive values.