Platelet distribution width as a prognostic factor in patients with COPD – pilot study

BACKGROUND Platelets may actively participate in inflammation in COPD. Platelet distribution width (PDW), a measure of platelets' volume heterogeneity, may increase in platelets' activation. We hypothesized that PDW may be a marker of hypercoagulation, which plays a significant role in conditions associated with worse survival of patients with COPD, eg, acute myocardial infarction and other forms of ischemic heart disease. METHODS Retrospective analysis of 79 patients. Variables were compared after grouping patients according to the upper normal limit of PDW, using Welch's t-tests or Mann-Whitney U, and chi-square tests. Survival in the two groups was compared using the Kaplan-Meier method and Cox proportional hazards regression. RESULTS Ten patients presented values of PDW above 16 fL, which was the upper limit of normality for our laboratory. Compared to patients with normal PDW, they had lower forced expiratory flow between 25% and 75% of vital capacity (FEF 25-75) - 35% of reference value vs 57% (P=0.003) and peak expiratory flow - 39% vs 54% (P<0.001). The median survival of patients with elevated PDW was 743 days compared to those with normal PDW (1,305 days) (P=0.025). The adjusted HR was 4.59 (95% CI: 1.1, 19.19; P=0.04). CONCLUSION Our analysis indicates that elevated PDW is associated with reduced survival of patients with COPD. If our data are to be confirmed, PDW may be used as an inexpensive and repeatable prognostic tool in COPD.