Diagnostic accuracy of different immunoassay classes as characterized by positive and negative likelihood ratios. Likelihood ratios (LR) are powerful measures describing how many times more (or less) likely a test result is in patients with the disease in contrast to patients without the disease.80 In the context of HIT, a test with a +LR above 10 (corresponding to a specificity of 90%) and a –LR below 0.05 (corresponding to a sensitivity of 95%) is considered favorable.