Impact of comorbidities and body mass index on the outcome of polycythemia vera patients

In 816 patients with 2016 World Health Organization-defined polycythemia vera (PV) enrolled in a multicenter retrospective study, we investigated the predictive value of Charlson comorbidity index (CCI) and body mass index (BMI) on thrombosis, progression to post-PV myelofibrosis (PPV-MF) and survival. Patients were subgrouped according to CCI = 0 (58.1%, no comorbidities) or CCI >= 1 (41.9%) and according to normal/underweight (BMI < 25, 54.5%) or overweight/obesity (BMI >= 25, 45.5%) at PV diagnosis. BMI was available for 529 patients. Patients with CCI >= 1 were older and more frequently presented cardiovascular risk factors compared to patients with CCI = 0 (p < 0.001), while overweight/obese patients were more frequently males (p < 0.001). Cumulative incidence of thromboses with death as competing risk was 13.3% at 10 years. Multivariable analysis with death as competing risk showed that previous thromboses (subdistribution hazard ratio [SHR]: 2.1, p = 0.01) and hypertension (SHR: 1.77, p = 0.04) were significantly associated with a higher thrombotic risk, while BMI >= 25 lost statistical significance (SHR: 1.69, p = 0.05) and CCI >= 1 was excluded after evaluation of goodness of fit. After a median follow-up of 6.1 years, progression to PPV-MF occurred in 44 patients, and 75 patients died. BMI >= 25 was associated with a lower probability of progression to PPV-MF (SHR: 0.38, CI95%: 0.15-0.94, p = 0.04) and better survival (hazard ratio [HR]: 0.42, CI95%: 0.18-0.97, p = 0.04). CCI >= 1 did not affect progression to PPV-MF (p = 0.44) or survival (p = 0.71). The evaluation of CCI and BMI may improve the prognostic definition of PV. In patients with hypertension an accurate evaluation of thrombotic risk is warranted.