Hydroxyurea use and Plasmodium falciparum prevalence among children with sickle cell anemia in Homa Bay, Kenya; a cross sectional study

Hydroxyurea, a mainstay of sickle cell management in the developed world, offers a range of potential benefits to children with sickle cell disease. There is strong evidence that hydroxyurea induces production of fetal hemoglobin (HbF) in red blood cells, which is generally associated with reduced morbidity and fewer incidents of clinical events in sickle cell patients. Based on literature from in vitro investigations, it has also been suggested that hydroxyurea may confer some protection against malaria parasitemia by inhibiting proliferation of the malaria-causing parasite - Plasmodium falciparum.

The purpose of this study was to examine the effects hydroxyurea use on P. falciparum infection, parasite density, HbF and morbidity among children with sickle cell disease living in a malaria endemic setting. We analyzed baseline data of 95 children (aged 1 – 10 years) enrolled in the EPiTOMISE clinical trial (Enhancing Preventive Therapy of Malaria in children with Sickle cell anemia in East Africa) between January 2018 and September 2018.

Our analyses showed no significant difference in the prevalence of P. falciparum infection between hydroxyurea users and non-hydroxyurea users, prevalence ratio [95% CI] = 1.14 [0.76, 1.71]. Among infected children, median (IQR) log parasites densities were also similar between hydroxyurea users, -0.96 (-1.67, 0.41) and hydroxyurea non-users, -0.12 (-1.32, 3.48), p-value=0.146.

We did observe substantial hematological benefits among hydroxyurea users including an approximate 1 unit increase in median hemoglobin concentration and a 2.7-fold increase in median percentage HbF. However, this observation did not translate to any meaningful difference in the prevalence of morbidity events.

In agreement with the few studies on hydroxyurea use in malaria endemic settings, these results suggest that there may be no added risk of P. falciparum infection to sickle cell patients who routinely use hydroxyurea. Furthermore, our results reflect that hydroxyurea use is associated with increased HbF and a better hematological profile in this population. There is need for more research on hydroxyurea use in sub-Saharan Africa to help resolve any existing concerns and conflicting data in the current body of literature.