Researchers have found evidence to suggest that phlebotomy and hydroxyurea (HU) provide real-world benefits for older patients with polycythemia vera (PV), but both treatments are underused.
In a study of more than 800 PV patients, phlebotomy and HU treatment were both associated with lower risks of death and thrombosis.
However, 39% of patients didn’t receive HU, and 36% didn’t undergo phlebotomy.
“Our study highlights the value of adhering to PV treatment guidelines,” said study author Nikolai A. Podoltsev, MD, PhD, of Yale Cancer Center in New Haven, Connecticut.
“Use of the two recommended treatments saves lives.”
Dr. Podoltsev and his colleagues described this survival benefit in Blood Advances.
The researchers studied data from the linked Surveillance, Epidemiology, and End Results–Medicare database. They collected information on 820 older adults diagnosed with PV from 2007 to 2013.
The patients’ median age was 77 (range, 71-83), 57% were female, 91.2% were white, 12.7% had a disability, and 13.2% had a prior thrombotic event.
Patients received the following PV treatments:
- Both phlebotomy and HU concurrently or sequentially (41.1%)
- Phlebotomy only (23.0%)
- HU only (19.6%)
- Neither phlebotomy nor HU (16.3%).
The median follow-up was 2.83 years. During that time, 37.2% of patients (n=305) died.
The median survival was 6.29 years for phlebotomy recipients and 4.50 years for non-recipients (P<0.01). The median survival was 6.02 years for HU recipients and 5.25 years for non-recipients (P<0.01).
In a multivariable analysis, receipt of phlebotomy was associated with decreased mortality. The hazard ratio (HR) for death was 0.65 (P<0.01) for phlebotomy recipients.
Increasing phlebotomy intensity (the number of phlebotomies per year) was also associated with decreased mortality, with an HR of 0.71 (P<0.01).
A higher proportion of days covered (PDC) by HU treatment was associated with decreased mortality as well.
The researchers said every 10% increase of HU PDC was associated with an 8% to 9% lower risk of death. The HR was 0.92 in a model where phlebotomy was a binary variable and 0.91 in a model that included the frequency of phlebotomy (P<0.01 for both).
In all, 36.1% of patients (n=296) had a thrombotic event, which includes venous and arterial thrombosis.
The incidence of thrombosis was 29.3% (n=142) in phlebotomy recipients and 46.0% (n=154) in non-recipients (P<0.01). The incidence was 27.6% (n=118) in HU recipients and 45.4% (n=178) in non-recipients (P<0.01).
In a multivariable analysis, receipt of phlebotomy was associated with a decreased risk of thrombosis, with an HR of 0.52 (P<0.01).
Increasing phlebotomy intensity was associated with a decreased risk of thrombosis as well, with an HR of 0.46 (P<0.01).
And every 10% increase of HU PDC was associated with an 8% lower risk of thrombosis. The HR was 0.92 in both models (P<0.01 for both).
“All of the patients we studied were high-risk for clot development, and we now know from our findings that guideline-recommended treatments reduce the risk of both thrombosis and death,” Dr. Podoltsev said.
“We hope that our research will raise clinicians’ awareness of and adherence to the guidelines and improve the outcomes of PV patients in the future.”
This research was supported by the Frederick A. DeLuca Foundation. Study authors reported relationships with 24 pharmaceutical companies.