Background: Pleural effusions due to heart failure are associated with a high 1-year mortality. Several hematological parameters have been shown to provide prognostic information in patients with cardiovascular diseases. The objective was to assess whether hematological markers can also provide prognostic information in patients with pleural effusion caused by heart failure.
Methods: This was a retrospective study of patients with pleural effusion due to heart failure who underwent a diagnostic thoracentesis. The hematological parameters evaluated were as follows: neutrophils, lymphocytes, neutrophil-to-lymphocyte ratio, platelet count, platelet-to-lymphocyte ratio, mean platelet volume (MPV), and MPV-to-platelet ratio. Patients were divided into two groups: those who died within 1 year and survivors of more than 1 year. Differences and possible correlations were analyzed with non-parametric tests. Diagnostic values were estimated. Survival analysis was performed using the Kaplan-Meier method. Cox regression analysis was performed to identify independent variables.
Results: Twenty five of 55 (45%) patients died within 1-year from thoracentesis. Patients who died in this period were older, aged 83 years (73 - 87, median and interquartile range, IQR) vs. 74 (65 - 82); with lower platelet count: 181 x 103 (140 - 258 x 103) vs. 241 x 103 (198 - 324 x 103); and higher MPV/platelet: 48.1 (34.9 - 75.6) vs. 35.6 (27.1 - 42.9). In the regression analysis only the MPV/platelet had statistical significance (p = 0.002). MPV/platelet > 50 had a specificity of 87% for 1-year mortality, and a ratio > 30 had a sensitivity of 84%.
Conclusions: Simple hematological parameters such as platelet count and MPV/platelet, may provide useful prognostic information for predicting 1-year mortality in patients with pleural effusion due to heart failure.