Association of platelet count and mean platelet volume with clinical outcomes in pulmonary embolism: A retrospective cohort study

Abstract Introduction Mean platelet volume (MPV) and platelet count have been proposed as prognostic markers in thrombotic and bleeding disorders, but findings remain inconsistent. Pulmonary embolism (PE), a common and potentially life-threatening condition, offers a relevant context in which to assess their clinical utility. This study evaluated the association between platelet indices, including thrombocytopenia, thrombocytosis, MPV, and outcomes in patients hospitalized with acute PE.Methods We conducted a retrospective cohort study of adult patients admitted with acute PE between 2018 and 2024 at a community hospital. Patients were stratified by admission platelet count: thrombocytosis (>450 ×10⁹/L), normal count (150–450 ×10⁹/L), and thrombocytopenia (<150 ×10⁹/L, further subdivided into Grades 1–4). MPV was categorized as <9 fL vs. ≥9 fL, cut-off was based on previous studies. Clinical and demographic variables were analyzed, and key outcomes—including ICU admission, bleeding events, in-hospital mortality, 30-day Venous Thromboembolism (VTE) readmission, and mean hospital length of stay (LOS). Categorical variables were assessed using Fisher's exact test, and continuous variables were compared using one-way ANOVA. Institutional Review Board (IRB) approval was obtained prior to study initiation.Results Among 302 patients with acute PE, 11 (3.6%) had thrombocytosis, 253 (83.8%) had normal platelet counts, and 38 (12.6%) had thrombocytopenia. MPV ≥9 fL was observed in 85 patients (28.1%). All but one patient received anticoagulation, the exception being a case of Grade 4 thrombocytopenia. MPV ≥9 fL was not associated with significant differences in demographics, provoked PE, cancer prevalence, or smoking status. There were no statistically significant differences in clinical outcomes, including ICU admission (41.0% vs. 31.7%, p = 0.1658), in-hospital mortality (8.4% vs. 10.1%, p = 0.8281), or length of stay (mean 7.5 vs. 7.2 days, p = 0.1015). Among patients with thrombocytopenia, ICU admission (44.7% vs. 32.7%, p = 0.2009), in-hospital mortality (15.8% vs. 8.7%, p = 0.2795), and bleeding events (13.2% vs. 8.4%, p = 0.5074) were numerically higher compared to patients with platelet counts >150 ×10⁹/L, though none reached statistical significance. Mean hospital length of stay was also similar (7.4 vs. 7.2 days, p = 0.7597). In the thrombocytosis group (n=11), clinical outcomes were variable: ICU admission occurred in 27.3% of patients, bleeding events in 18.2%, and in-hospital mortality in 9.1%. Mean length of stay was 6.9 days. Due to the small sample size, no statistical comparisons were performed.Conclusion Platelet count and MPV were not independently associated with adverse outcomes in patients hospitalized for acute PE. MPV ≥9 fL and thrombocytopenia showed no significant associations with mortality, ICU utilization, bleeding, or length of stay. These findings may suggest that platelet indices have limited prognostic utility in the management of acute PE and should not replace established clinical risk assessment tools.Clinical Implications Our findings support the safety of anticoagulation in most patients with mild-to-moderate thrombocytopenia and underscore that neither MPV nor platelet count meaningfully predicts PE outcomes. Despite their ease of measurement, these indices should not guide clinical decision-making in isolation. Larger, multicenter studies are warranted to determine whether platelet-based markers may be relevant in select subpopulations, such as patients with active cancer or high bleeding risk.