Abstract
Thrombotic complications characterize the clinical course of polycythemia vera (PV)
and represent the main cause of morbidity and mortality. However, uncertainty still
exists as to the benefit/risk ratio of aspirin prophylaxis in this setting. In vivo
platelet biosynthesis of thromboxane A2 is enhanced and can be suppressed by low-dose aspirin in PV, thus providing a rationale
for assessing the efficacy and safety of a low-dose aspirin regimen in these patients.
The Gruppo Italiano Studio Policitemia Vera has recently performed a pilot study on
112 patients randomized to receive aspirin, 40 mg daily, or placebo and followed for
16±6 months (mean±SD). This study showed that low-dose aspirin is well tolerated in
PV patients, and that a large-scale efficacy trial is feasible in this setting.
In this article we report the protocol of the European Collaboration on Low-dose Aspirin
in Polycythemia Vera (ECLAP) study, which is a randomized trial designed to assess
the risk/benefit ratio of low-dose aspirin in PV. To estimate the size and the follow-up
duration required for the ECLAP trial, a retrospective analysis of the clinical epidemiology
of a large PV population has recently been completed by the Gruppo Italiano Studio
Policitemia Vera. On this basis, approximately 3500 patients will be enrolled in the
ECLAP study with a follow-up of 3 to 4 years.
The uncertainty principle will be used as the main eligibility criterion: Polycythemic
patients of any age, having no clear indication for or contraindication to aspirin
treatment, will be randomized in a double-blind fashion to receive oral aspirin (100
mg daily) or placebo. According to current therapeutic recommendations, the basic
treatment of randomized patients should be aimed at maintaining the hematocrit value
≤ 45% in subjects aged ≤50, and hematocrit <45% as well as platelet count <400 × 109 /L in patients aged >50. Randomization will be stratified by participating center.
The study is funded by the European Union BIOMED 2 program.
Keywords:
Polycythemia vera - aspirin - lowdose ASA - thrombosis - ECLAP trial
