Sensitivity and specificity of immunoassay classes for diagnosis of HIT. Results of an HSROC model are reported showing the summary point (red quadrant), a 95% CI region (dashed yellow line), and 95% prediction region (dashed green line), illustrating a confidence region for the true sensitivity and specificity in a possible future study. Results of primary studies are shown as circles; the sample size of the studies is represented by the size of the circle.