Platelet count as a prognostic marker for acute respiratory distress syndrome

Background This study aimed to evaluate the role of platelet count (PLT) in the prognosis of patients with acute respiratory distress syndrome (ARDS). Methods The data were extracted from the Medical Information Mart for Intensive Care database (version 2.2). Patients diagnosed with ARDS according to criteria from Berlin Definition and had the platelet count (PLT) measured within the first day after intensive care unit admission were analyzed. Based on PLT, ARDS patients were divided into four groups: PLT <= 100x 10(9)/L, PLT 101-200x 10(9)/L, PLT 201-300x 10(9)/L, and PLT > 300x 10(9)/L. The primary outcome was 28-day mortality. Survival probabilities were analyzed using Kaplan-Meier. Furthermore, the association between PLT and mortality in ARDS patients was assessed using a univariate and multivariable Cox proportional hazards model. Results Overall, the final analysis included 3,207 eligible participants with ARDS. According to the Kaplan-Meier curves for 28-day mortality of PLT, PLT <= 100x 10(9)/L was associated with a higher incidence of mortality (P = 0.001), the same trends were observed in the 60-day (P = 0.001) and 90-day mortality (P = 0.001). In the multivariate model adjusted for the potential factors, the adjusted hazard ratio at PLT 101-200x 10(9)/L group, PLT 201-300x 10(9)/L, and PLT > 300x 10(9)/L was 0.681 [95% confidence interval (CI): 0.576-0.805, P < 0.001], 0.733 (95% CI: 0.604-0.889, P = 0.002), and 0.787 (95% CI: 0.624-0.994, P = 0.044) compared to the reference group (PLT <= 100x 10(9)/L), respectively. Similar relationships between the PLT <= 100x 10(9)/L group and 28-day mortality were obtained in most subgroups. Conclusion PLT appeared to be an independent predictor of mortality in critically ill patients with ARDS.