[Evaluation of outcome based on platelet function in elderly patients with various diseases]

This study was conducted to clarify the relationship between the outcome of various diseases in elderly patients and platelet function. The outcome in 347 consecutive patients aged 60 or older, who were treated without antiplatelet drugs on registration, was retrospectively studied after platelet aggregability tests. The mean age was 77.5 years (161 men and 186 women). The grading curve (GC) type, as an index of platelet aggregability, was determined spectrophotometrically with an aggregometer and adenosine-5'-diphosphate as an agonist. They were classified into three groups according to GC type: Group I with a GC type of -2 or -1 (n = 40), group II with a GC type of 0 or +1 (n = 208), and group III with a GC type of +2 or +3 (n = 99). The mean follow-up period was 3.9 years. There were 3 deaths in group I, 33 in group II, and 30 in group III. Mean annual mortality rate was 2.1% in group I, 4.0% in group II, and 7.5% in group III. Among causes of death, vascular events was seen in 15 patients of group III, although the most common cause of death was pneumonia in the three groups. The annual mortality rates due to vascular events were 0.7% in group I, 0.6% in group II, and 4.2% in group III, indicating a significantly higher mortality rate in group III. Antiplatelet therapy was performed in approximately 15% of each group during their clinical course, and, when they were excluded for survival analyses, annual mortality rate was also higher in group III than in groups I and II. Cox proportional hazards models for vascular death yielded a hazard ratio of 2.3 and 2.2 in the increased GC type and diabetes, respectively. These findings indicated that elderly patients with accelerated aggregability had higher mortality rates due to vascular events. Therefore, accelerated aggregability in the elderly suggested not only the progress of arteriosclerosis, but indications of antiplatelet therapy to prevent vascular events.