Platelet count as an evolution marker of late mortality and cardiovascular events after an episode of community-acquired pneumonia

Introduction: The persistence of inflammation in community-acquired pneumonia (CAP) patients could lead to appearance of cardiovascular events and higher mortality. Circulating platelets contribute to innate immunity with multiple potential connections to pneumonia. Our propose was to analyse the association between platelet count (PC) in a CAP episode and outcome during 1-year follow-up. Material and Methods: Retrospective study of hospitalized CAP patients. PC in blood tests were performed at two points: admission and early- stage evolution (day +3/5). The outcome variables were Mortality from any cause and Major Adverse Cardiovascular Events (MACE; defined as Mortality, Acute Myocardial Infarction or Stroke) during 1-year follow-up. Results: 351 hospitalized CAP patients were studied. The PC in the early-stage evolution determination were significantly lower in patients who suffered MACE during follow-up (No_MACE 261.000/mm3 Vs MACE 225.000/mm3, p=0.036). Evolution of PC determinations during hospitalization was analysed. Patients with normal PC at admission and appearance of thrombocytopenia (<150.000/ml) in the early stage evolution showed the worst 1-year outcome prognosis, not only for all-cause mortality (p=0.002, HR=7.75) but also for MACE (p=0.002, HR=7.4), regardless of age, severity of pneumonia and comorbidities. Conclusions: The evolution of circulating PC between admission and early stage evolution is related to higher risk of MACE in CAP patients during the post-episode year. Furthering the study of platelets and their activation could be useful as prognostic biomarkers in order to strengthen the prevention of long-term cardiovascular events.