[Factors influencing platelet function in elderly patients with chronic phase thrombotic diseases]

To clarify the factors influencing platelet function in elderly patients with chronic thrombotic disease, platelet aggregability was studied in 839 blood samples from 497 patients with a variety of diseases. Clinical stage (thrombotic disease), vascular risk factors, and data concerning any administration of antiplatelet drugs were assessed, as well as brain computerized tomographic and carotid ultrasonographic findings. Platelet aggregability was determined spectrophotometrically with an aggregometer (PAM-8T) and adenosine-5'-diphosphate as an agonist to determine new parameters: the grading curve (GC) type, and platelet aggregability threshold index (PATI). Multiple regression analysis showed that the antiplatelet therapy greatly influenced the GC type. Platelet aggregability, which accelerated with aging, was strongly suppressed by ticlopidine. Furthermore, excluding samples with antiplatelet therapy, statistical analysis showed that platelet aggregability was accelerated in women, and in patients with bilateral or complicated carotid lesions, although these patients were significantly older than the others. These findings suggested that accelerated aggregability in the elderly substantially reflected the progress of arteriosclerosis with age. Moreover, the findings indicated that the determination of GC type and PATI were useful in monitoring elderly patients receiving antiplatelet therapy, especially with ticlopidine.