Bleeding manifestations in primary
immune thrombocytopenia (
ITP) range from skin
petechiae to life-threatening
intracranial hemorrhage (ICH). However, the relation between these various
bleeding manifestations and the platelet count in
ITP remains poorly characterized. Using a nationwide database of patients with
ITP during the years 2005 to 2014 (10 years) in Japan, we analyzed 19 415 adult patients newly diagnosed with
ITP, including 222 with ICH. The frequency of skin
purpura was 64.8%, and this increased linearly with
thrombocytopenia without a specific platelet count threshold. In contrast, mucosal
bleeding (
epistaxis and gingival
bleeding) and organ
bleeding (
melena,
hematuria, and ICH) increased exponentially with
thrombocytopenia at a platelet count threshold of 10 to 15 × 109/L. Age showed a much weaker correlation than platelet count with skin and mucosal
bleeding. However, the incidence of organ
bleeding increased exponentially above 60 years of age. Multivariate analysis showed that the presence of mucosal
bleeding was a risk factor for occurrence of
melena and
hematuria but not for ICH. The frequency of ICH was 1.1% and risk factors for ICH were age ≥60 years (odds ratio [OR], 3.09; 95% confidence interval [CI], 2.13-4.47; P < .001), platelet count <10 × 109/L (OR, 2.96; 95% CI, 2.11-4.15; P < .001), and the presence of
hematuria (OR, 1.56; 95% CI, 1.04-2.35; P = .033). The relation between ICH and platelet count varied with age. This large-scale analysis of risk factors for
bleeding in
ITP has revealed distinct characteristics of skin, mucosal, and organ
bleeding in adult patients with newly diagnosed
ITP, thus indicating those who are at a high risk of severe organ
bleeding.