Assay results in HIT-negative and HIT-positive subjects. Results from HIT-negative and -positive subjects are shown for the polyspecific ELISA (A), IgG-specific ELISA (B), KKO-I (C), and DT40-luc (D). Solid horizontal lines represent mean values. Dashed horizontal lines represent the cutoff associated with the most northwest point on the receiver operating characteristic curve (ie, the cutoff at which sensitivity and specificity are optimized) for each assay.