Risk Stratification and Treatment Considerations in PV

Jamile Shammo, MD, FASCP, FACP: Once a diagnosis in polycythemia vera [PV] is made, the next step would be to assess the risk in this patient population. The risk in polycythemia vera pertains to the risk of thrombosis. Generally, it’s been stated that patients who are below the age of 60 and those who have not had a thrombotic event belong to a lower-risk group, essentially meaning that the risk of thrombotic events is lower. Patients who have 1 or the other risk factors—they are older than age 60 or have had a thrombotic event—have a higher risk, primarily because they have a higher risk of developing a future thrombotic event. All those patients require managing their hematocrit. It should be kept below 45%, and we can discuss data as to why that needs to be the case. They also all need to receive low-dose aspirin, 81 mg. Of course, there are data on a dose of 2 baby aspirins a day to prevent thrombotic events. That is universally recommended for all patients to prevent future thrombotic events. 

There are practical implications for assessing risk in this patient population, and that pertains to the utilization of cytoreduction. Patients who have higher-risk PV ought to be considered for cytoreductive therapy. That is why we need to do the risk stratification in this patient population. Of course, we need to do a lot more when we make the diagnosis: we need to do an evaluation of their spleen size, and we need to consider symptoms at baseline and follow that as we go along when we are seeing patients in the clinic periodically.

We need to think about when to treat patients who have polycythemia vera because, as we evaluate them at baseline, we need to be cognizant of their symptomatology and their blood counts as well as their spleen-related symptoms. Those are the triads of polycythemia vera symptomatology. They are the points of care, if you will. Relative to the blood counts, if a patient has a hematocrit level of over 45%, that needs to be addressed, and they need to have immediate phlebotomy. We talked about low-dose aspirin for all patients, so that has to be also addressed. That is considered therapy whether they are symptomatic or not. I don’t know whether that falls under surveillance, but in my book, that is considered treatment. 

Once the patient reaches those points—they have a hematocrit level below 45%, they are on aspirin, they have no other constitutional symptoms like pruritus or bone pain or symptoms related to splenomegaly—then I’m happy to surveil them. I will be monitoring them throughout their disease course, perhaps every 3 to 6 months, perhaps more frequent initially. It may be less frequent later on, or once I’m certain of the stability of their disease scores.

It would be extremely important to monitor their constitutional symptoms as well as symptoms of their spleen. There are symptom assessment forms that would come in extremely handy, and they are available on various websites. These are really helpful when trying to evaluate and follow up on patients who have chronic conditions and with symptoms that may vary over the course of many years, so I do employ those. They would be helpful either at baseline or when you are initiating treatments. 

For people who already come in with larger spleens, who already have symptoms of pruritus, and people who can’t even sleep because of constitutional symptoms like night sweats and pruritus, you clearly need to institute cytoreduction. We can talk about various available treatment options including hydroxyurea, which seems to be the most common treatment option that we utilize. For patients who are younger and desire to have children, interferons are the other possibility.

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