Table 3

Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of assays for a diagnosis of C1 inhibitor deficiency

C4C1 inhibitor (immunochemical)Functional C1 inhibitorC4 and functional C1 inhibitor
The PPV associated with the immunochemical C1 inhibitor measurement incorporates type 2 hereditary angioedema. The C1 inhibitor values will be normal or raised despite functional deficiency.
C1inhD, C1 inhibitor deficiency.
Using all samples
Using first samples in study period
Using untreated C1inhD v first sample from non-C1inhD