Essential thrombocythemia is a chronic disease common in people over age 50 and slightly more common in women. Young people can develop it as well. It is characterised by the overproduction of platelets by megakaryocytes in the bone marrow. Essential thrombocythemia is an uncommon disorder where the body produces too many blood platelets. This condition may cause to feel fatigued, lightheaded and to experience headaches and vision changes. It also increases the risk of blood clots.
The greatest health risk in patients with ET is an increased risk of developing blood clots. Blood clots can be in the deep vessels of the legs or lungs; ET patients are also more likely to experience strokes and heart attacks. ET patients can develop clots elsewhere, including within the abdomen, an otherwise rare site for clots to form. The risk of clotting increases with age, and disease-associated risks may be quite different for children than for adults, with children generally being at low risk for clots and other problems related to ET.
The median patient age was 65 years. Thrombosis rates at and after diagnosis of ET were comparable to those of white patients, but bleeding rates at and after diagnosis were much lower. The projected 10-year thrombosis-free, bleeding-free, and overall survival rates were 66%, 83%, and 80%, respectively. There were no deaths among patients 60 years or younger during a maximum follow-up of 15 years, and splenomegaly at diagnosis of ET appeared to protect against thrombosis. In multivariate analysis, advanced age predicted inferior 10-year thrombosis-free and overall survival, and male sex predicted inferior bleeding-free survival. Half the deaths were related to ET. The probability of myelofibrosis transformation was 9.7% at 10 years. Prior myelofibrosis (P = .008) and the use of melphalan treatment (P = .002) were risk factors for acute myeloid leukemia evolution.