Take-aways:
- REVEAL is the largest prospective and contemporary cohort of patients with PV in the United States.
- Approximately 35% of patients died due to vascular/thrombotic complications, with 28% having elevated hematocrit and myeloproliferation in the 6 months before death.
- The estimated 4-year mortality rate was >10%, a “surprising” finding given the mean age at enrollment was only approximately 66 years.
In the contemporary era, thrombotic complications are a leading cause of death in patients with polycythemia vera (PV), and more than one-quarter of individuals with the condition have elevated hematocrit or uncontrolled myeloproliferation in the 6 months prior to death. This is according to results of a real-world study presented during the 2021 Society of Hematologic Oncology Annual Meeting by Carole B. Miller, MD, of Ascension Saint Agnes Hospital in Baltimore, Maryland.
According to the investigators, retrospective evaluations represent the primary source of data on survival in patients with PV, suggesting there may be gaps in knowledge regarding the real-world survival rates of patients with the condition. Likewise, cause of death in PV is typically ill defined, the researchers noted. To close these knowledge gaps, Dr. Stein and colleagues evaluated the characteristics, survival-by-risk, and causes of death in a real-world PV population using final data from the Prospective Observational Study of Patients with Polycythemia Vera in US Clinical Practices (REVEAL).
The study included 2,510 patients with PV who were followed during usual care visits between 2014 and 2016 until either death, study withdrawal, or the end of the study. A total of 244 patients (9.7%) died during the study, while most patients (90.3%) were still alive at the last follow-up visit. The mean follow-up periods were 110.3 weeks for those who died and 179.4 weeks for those still alive at last visit.
More than 1 in 3 patients (35%) experienced a thrombotic event at death. In the 6 months prior to death, 31.1% of patients had at least 1 elevated hematocrit value, 57.9% had at least 1 elevated white blood cell (WBC) count, and 36.8% had at least 1 elevated platelet count. Nearly 28% of patients had at least 1 elevated WBC and platelet count.
Overall, the 4-year survival probability was 89%. However, the authors noted that 4-year survival probability was lower for high-risk patients who were age 60 years or older and/or had a history of thrombotic events (86% vs. 97%; P < .001). As seen in Figure 1, thrombotic complications were reported as the primary cause of death in most patients (33.1%).
Patients who died were significantly older at diagnosis compared with living patients (mean age, 68.5 vs. 60.2 years, respectively; P < .001). In addition, those who died had significantly longer mean disease duration from diagnosis to enrollment (6.5 vs. 5.7 years; P = .06).
A greater proportion of patients who died also had comorbidities, including:
- vascular disorders (72.1% vs.62.3%)
- neoplasms (47.5% vs. 22.2%)
- respiratory comorbidities (55.7%vs. 33.4%)
- infectious comorbidities (41.0%vs. 26.3%)
- cardiac disorders (41.0% vs.12.1%)
- blood/lymphatic comorbidities (31.1% vs. 18.5%)
According to the investigators, the observation of higher respiratory disorder rate in deceased patients deserves more attention. “The high rate of respiratory disorders observed in the deceased population, both as comorbidities and causes of death, has not been well characterized in other PV mortality studies,” Dr. Stein reported. “[This finding] warrants further investigation of whether some patients may have undiagnosed pulmonary hypertension.”
Disclosures: This research was supported by Incyte Corporation. Study authors report financial relationships with Incyte Corporation.
Reference
Stein BL, Patel K, Scherber R, et al. Mortality and causes of death of patients with polycythemia vera: Analysis of the reveal prospective, observational study. Abstract #MPN-133. Presented at the 2021 Society of Hematologic Oncology, September 8-11, 2021.