High red cell mass and high plasma volume are independently associated with thrombotic risk in polycythemia vera

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Author contributions

IK and ML wrote the first draft of the manuscript, performed research and data analysis, and supervised the study. DL and AB performed research and data analysis and revised the first draft of the manuscript. All authors approved the final version of the manuscript.

Ethics

The study was conducted in accordance with the Declaration of Helsinki and approved by the University Clinical Center of Serbia, Belgrade, Serbia, Institutional Review Board (499/05, date 30.11.2021). Due to retrospective design of the study, informed consent was waived.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Statistical methods

Statistical calculations were performed with MedCalc Statistical Software^® (Ostend, Belgium, version 22.016). Shapiro–Wilk’s test was used to check for data distribution. Categorical variables were compared using the chi-squared test and continuous variables were compared with the Kruskall–Wallis test. Receiver operating curve analysis with thrombosis as a classification variable was used for the determination of the optimal cutoff values of red cell mass and plasma volume. Survival analyses were performed with the Kaplan–Meier method, the log-rank test, and the Cox regression analysis. Time to thrombosis (composite arterial/venous) was measured from the time of disease diagnosis until a thrombotic event or the last follow-up visit with death being a censoring event. Arterial thrombotic events considered were acute myocardial infarction, transitory ischemic attack, ischemic stroke or acute peripheral arterial occlusion; venous thrombotic events of interest were pulmonary embolism and/or deep vein thrombosis. Overall survival was measured from the time of diagnosis until death or the last follow-up visit.

Data availability statement

Data used for the generation of this study is available upon reasonable request directed at the corresponding author (Danijela Lekovic).