A Comparative Study of Haematological Parameters between Sickle Cell Anaemia Patients on Hydroxyurea and Hydroxyurea Naïve Patients at Kenyatta National Hospital, Kenya

Abstract

Sickle cell anaemia is an autosomal recessive blood disorder that has over the years been a big burden on healthcare in Kenya and Africa as a whole. The disease tends to be caused by a point mutation that occurs in the beta globin chain of red blood cells. The gene Adenine (A) is replaced by the gene Thyamine (T). This in turn causes an alteration of the amino acids from the hydrophilic Glutamic Acid to the hydrophobic Valine. This in turn causes the production of red blood cells that tend to sickle in hypoxic conditions, HbS. The production of this type of red blood cells is characterized by various complications. The symptoms include; anaemia, jaundice, stroke, bacterial infections, vaso occlusive crises, acute chest syndrome, splenic sequestration among others. Vaso occlusive crises is one of the major complications of the condition. This is whereby a patient experiences a substantial amount of pain in any body part. Most commonly in the back, chest or legs. This pain occurs when the sickled red blood cells block the flow of blood to certain tissues thus depriving them of oxygen. This in turn causes the body to initiate an inflammatory response so as to deal with the problem. The key strategy in the management of these patients is achieving a steady state. This refers to a situation whereby a patient has not experienced any illness or any vaso occlusive crises and has not received any blood transfusion in a duration of at least 3 consecutive months. In order to achieve this, sickle cell patients have to take a lifelong regimen of a drug named hydroxyurea (HU). This drug is not provided free and due to this and various other reasons, some patients within the Kenyan population have been found not to take this daily medication. Other various reasons such as a belief the drug would cause cancer, side effects felt from it and a lack of understanding of its purpose contributes to non-compliance to taking it. Sickle cell anaemia patients require routine laboratory analyses which include a full blood count. The full blood count is the test most utilized in the routine monitoring of these patients. However, there is no data that depicts the differences, if any, of the haematological parameters within the Kenyan sickle cell population and such data would lead to enhancing the management of these patients through hydroxyurea by both their clinicians and caregivers. The objective of this study was to compare the haematological parameters; haemoglobin levels (Hb), white blood cell (WBC) counts and Platelet (Plt) counts, of sickle cell patients in steady state, both those taking hydroxyurea and those not taking hydroxyurea. For this a comparative cross-sectional study was carried out at the Kenyatta National Hospital where 92 sickle cell patients in steady state were selected by systematic sampling. Of these, 46 patients were compliant to taking hydroxyurea and the other 46 patients were not taking hydroxyurea at all for a period not less than 3months. Upon giving consent, about 2ml of whole blood was collected from each participant and placed in vacutainers containing the anticoagulant Ethylene Diamine Tetra Acetic Acid. This blood was then evaluated for full blood counts, obtaining parameters including the white blood cell counts, haemoglobin levels and platelet counts. Demographic data was collected using a questionnaire, which was also used to collect data for screening of participants and collected data entered into a database. The student t test, two sample t test assuming unequal variance, was then used to assess the significance of difference between the respective means of the groups. A p value of less than or equal to 0.05 was considered statistically significant in this comparison. The mean haemoglobin level of the group of patients on hydroxyurea was found to be significantly higher compared to the mean haemoglobin level of the hydroxyurea naïve group. On the other hand, the mean white blood cell count of the group of patients on hydroxyurea was found to be significantly lower compared to the mean white blood cell count of the hydroxyurea naïve group. The mean platelet count of the group of patients on hydroxyurea was also found to be significantly lower compared to the mean platelet count of the hydroxyurea naïve group. In conclusion, a statistically significant difference between the haemoglobin, white blood cell counts and platelet counts was noted between the two groups. This included a higher mean in Hb in the group of patients on hydroxyurea and a lower mean in white blood cell count and platelet count. These findings lead to the conclusion that hydroxyurea has a significant impact on the haematological parameters of sickle cell patients. This impact is positive and it consequently leads to an overall positive impact on health status for sickle cell patients. Studies such as this can form a basis for further research on the mechanism of action of hydroxyurea on the blood parameters.