Indicators of clinical severity did not differ between patients with aHIT and those with classical HIT. A cohort of 43 patients with suspected HIT were qualitatively subgrouped as aHIT-positive (>50% in no-heparin SRA; n = 34) or aHIT-negative/classical (≤ 50% in no-heparin SRA; n = 9). (A) Platelet count nadir and (B) time to platelet recovery are displayed using violin plots with means displayed (dashed line). aHIT and classical HIT subgroups were compared using a nonparametric, unpaired t test (Mann-Whitney test). The time to platelet recovery was calculated based on the number of days between heparin cessation and the day the platelet count returned to >150 × 109/L. Four patients died or were discharged before achieving a normal platelet count and were excluded from the analysis presented in panel B. (C) The number of patients with objectively confirmed thromboses (4Ts thrombosis score of 2) was compared between the aHIT and classical HIT subgroups using Fisher's exact test, and the percentage of patients with confirmed thromboses is displayed.
