Platelet count and the risk for thrombosis and death in the elderly

Aim: Our aim was to examine the association between platelet count and the incidence of myocardial infarction, ischemic stroke, hemorrhagic stroke, venous thrombosis, and mortality. Methods and results: Platelet count was measured at baseline in 1989-1990 and at 3years follow-up, or at baseline (for a newly recruited group) in 1992-1993 in 5766 community-dwelling individuals aged 65years and older (mean age at baseline, 73years). During 12-15years of follow-up, there were 821 incident myocardial infarctions, 807 ischemic strokes, 161 hemorrhagic strokes, 159 venous thrombotic events, and 3413 participants died. Platelet count was not associated with the occurrence of myocardial infarction, ischemic or hemorrhagic stroke, venous thrombosis, or cardiovascular mortality. Non-cardiovascular mortality was higher among both participants with low and with high platelet count. Adjusted non-cardiovascular mortality rates for platelet counts below 100, 100-199, 300-399, and above 400 × 10⁹ L^-1 relative to the reference mortality rate in participants with platelet count values between 200 and 299 × 10⁹ L^-1 were 1.89 (1.21-2.96), 1.08 (0.98-1.20), 1.20 (1.06-1.37), and 1.47 (1.14-1.90), respectively. Conclusion: Platelet counts were not associated with vascular outcomes but low and high platelet counts were associated with non-cardiovascular mortality, including cancer mortality.