Beyond the platelet count: immature platelet fraction and thromboelastometry correlate with bleeding in patients with immune thrombocytopenia

Platelet counts (PC) estimate bleeding risk in Immune Thrombocytopenia (ITP). We investigated whether measures of thromboelastometry and absolute immature platelet fraction (A‐IPF) would correlate better with acute bleeding score (ABS) than PC or mean platelet volume (MPV). Simultaneous determination of ABS, complete blood count and thromboelastometry was performed in 141 ITP patients; 112 underwent A‐IPF testing. Subgroup analyses were performed for paediatric subjects, PC <60 × 10⁹/l and <30 × 10⁹/l. PC significantly inversely correlated with ABS in all subjects, PC <30 × 10⁹/l and total paediatric cohort. MPV did not correlate with ABS in any subgroup. Thromboelastometry measures of clot firmness, but not PC, significantly correlated with ABS in all subjects with PC <60 × 10⁹/l, and children with PC <60 × 10⁹/l and <30 × 10⁹/l. A‐IPF demonstrated stronger correlation with ABS than did PC among all subjects, those with PC <60 × 10⁹/l, all children and children with PC <30 × 10⁹/l (r = ?0·37; r = ?0·34; r = ?0·44; r = ?0·60) versus ABS with PC (r = ?0·36; ns; r = ?0·32; ns). Stronger correlations of both thromboelastometry measures of clot firmness and A‐IPF than PC with ABS suggest factors beyond PC, i.e. related to platelet function, contribute to ITP bleeding pathophysiology. Thromboelastometry, A‐IPF and ABS can be incorporated into routine or acute visits.