Immune Thrombocytopenia in Older Adults: Age-Related and Disease-Specific Alterations in Platelets.

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder with a higher incidence among older adults. Aging per se alters platelet characteristics, including reduced reactivity and increased caspase activity, changes also observed in ITP. The aim of this study was to assess the impact of aging on the hemostatic characteristics of patients with ITP and its potential contribution to the increased burden of the disease. Additionally, the study sought to identify characteristics of the disease itself, independent of age. Patients with ITP over 65 years of age (ITP>65) and patients aged 65 or under (ITP≤65) were included, as well as age-matched healthy controls (HC). Basal P-selectin exposure was higher in the ITP≤65 than in the HC≤65 group but no difference was observed between the ITP>65 and HC>65 groups. This may be due to the synergistic effect of disease and aging, because P-selectin exposure was higher in the HC>65 group than in the HC≤65 group. The ITP>65 patients exhibited reduced platelet responsiveness to agonists and increased caspase-3/7 activity compared with the ITP≤65 patients. Their clots were more resistant to lysis, likely due to elevated plasma levels of circulating cell-free DNA (cfDNA) and plasminogen activator inhibitor-1 (PAI-1). Comparisons between the ITP≤65 and HC≤65 groups as well as the ITP>65 and HC>65 groups revealed ITP-specific features, such as reduced sialic acid residues due to elevated neuraminidase-1 (NEU1) exposure. These findings showed that age-related changes in haemostasis can overlap with disease-specific features, highlighting the need for age-stratified approaches.