Phlebotomy vs. Myelosuppressive Medications in Controlling Erythrocytosis in Polycythemia Vera (PV) Patients: Impact upon Fatigue in a Survey of 405 PV Patients.
Authors: Mesa Ruben A. , Niblack Joyce , Tan Angelina D. , Atherton Pamela J. , Sloan Jeff A. , Tefferi Ayalew 
Published: April 2020

Abstract
Background: Current dogma for the management of patients with PV dictates controlling erythrocytosis (to goal hematocrit levels of &lt;45% (males) or &lt;42%(females)) to decrease risks of thrombohemorrhagic complications. Control is achieved by either phlebotomy (through induction of iatrogenic iron deficiency), and/or direct myelosuppression (through hydroxyurea, interferon-alpha, or anagrelide). Although phlebotomy is clinically considered a very benign therapy, we hypothesize that PV associated fatigue is exacerbated by iron deficiency induced fatigue (Qual Life Res2000;9:5(491–7)), and evaluated the impact of therapeutic control of erythrocytosis on PV patients.
Methods: A detailed analysis of patients with PV whom responded to an international web based survey of MPD patients which registered responses regarding diagnosis, disease course, current medications, current blood counts, frequency of phlebotomy, constitutional symptoms, and fatigue (FACT-An and Brief Fatigue Inventory).
Results: A total of 405 self reported PV patients (median age 56; 48% female) from a wide geographic international distribution responded. Individuals were a median of 4 years from their initial diagnosis of PV (range 0–36). Prior PV associated complications were reported as thrombotic (n=98; 24%), hemorrhagic (n=101; 25%), or both events (n=37; 9%). When these latter values were combined with age (i.e. &gt;60 years) 61% of patients (n=246) would be considered high risk. Therapy for their PV was reported by 96% (n=388) patients, with 89% (361) having been phlebotomized, 72% (n = 291) received aspirin, 64% (n = 261) having received 1 or more myelosuppressive agent (hydroxyurea 53% (n = 216), anagrelide 22% (n = 88), interferon-alpha 16% (n = 63)). Amongst patients whom were phlebotomized over the past year (43%; n =174: median 4 units (range 1–18)), 53% (n = 92) received concurrent myelosuppressive therapy. Amongst patients whom originally, but no longer required phlebotomy 35% (n = 142), 94% (n = 134) were receiving myelosuppressive treatments. QOL assessments indicated fatigue as measured by both instruments is clearly increased across the PV respondents compared to published controls for those instruments (p&lt;0.001). Additionally, although the burden of fatigue was not significantly higher in “high-risk” PV, fatigue levels were higher amongst those with prior thrombo-hemorrhagic events (p=0.03, or both types of events p&lt;0.01). In regards to the impact of PV therapy upon fatigue, the burden of this symptom was not significantly diminished for those individuals on phlebotomy alone compared to those on cytoreductive therapy. Neither did fatigue levels correlate with the frequency or intensity of phlebotomy. Additionally, although fatigue burden was high (compared to controls) amongst patients on cytoreductive therapy, no agent had a clear advantage in alleviating (or disadvantage in exacerbating) fatigue.
Conclusions: Fatigue amongst patients with PV is significantly increased compared to controls, and no therapeutic option seems to have a significant advantage with regards to fatigue. Given the multifactorial and subjective nature of fatigue it is impossible to separate the individual contributions of disease activity and therapy to the burden of fatigue in these patients. Hopefully, targeted therapy against the molecular origins of myeloproliferation in these patients will lead to better improvements in fatigue than current options offer.