Kaplan-Meier curve displaying the percentage of patients testing positive on different PF4 assays over time. The positivity cutoff for the Stago and Immucor assays comprised ODs of 0.238 and 0.4, respectively, and an event was recorded as soon as the patient had a negative ELISA. n = 33, Stago assay; n = 34, Immucor assay.