DETERMINATION OF CLINICAL PHENOTYPES OF PATIENTS WITH SICKLE CELL ANAEMIA IN KANO, NIGERIA

Abstract

The aim of this study was to determine the pattern of clinical presentations of individuals
with sickle cell anaemia (SCA) using haematologic and haemolytic markers in the steady
state and to evaluate the relationships between these parameters and disease severity with a

15

view to categorizing the patients into haemolysis associated or vaso-occlusion associated
phenotypes.

This was a descriptive cross-sectional study conducted among individuals with sickle cell
anaemia in steady state attending the Adult Haematology Clinic of Aminu Kano Teaching
Hospital (AKHT) Kano, Nigeria. A structured questionnaire and case files were used to
obtain clinical information on the patients. Haematological (i.e. haematocrit, haemoglobin,
platelet count, white cell count, foetal haemoglobin) and biochemical (i.e. lactate
dehydrogenase, total bilirubin, direct bilirubin, indirect bilirubin, aspartate aminotransferase)
parameters were measured. Serum lactate dehydrogenase was used as a surrogate maker of
haemolysis to categorize the patients into two clinical phenotypes. Data was analyzed to
obtain descriptive and inferential statistics using the Statistical Package for Social Sciences
(SPSS) version 16 and p ≤ 0.05 was considered statistically significant.

One hundred and twenty (120) individuals between 18 and 43 years of age were recruited,
consisting of 91 females and 29 males (M: F ratio; 1: 3.1). Majority of individuals in the
study had moderate disease severity (52%), while 40.8% had mild disease and 5% severe
disease. The mean severity score was 2.91 ± 1.3. The common clinical presentations were;
painful crisis 112 (93.3%), osteonecrosis/hip replacement 17 (14.2%), chronic leg ulcer 16
(13.3%), stroke 13 (10.8%), priapism 7 (5.8%), renal impairment 6 (5%) and acute chest
syndrome 6 (5%). The mean steady state haematologic and haemolytic values were
haematocrit 23.2 ± 4.5%, haemoglobin 7.7 ± 3.1 g/dl, white blood cell count 12.1 ±
3.6×109/L, platelet count 366.1 ± 131.3×109/L, foetal haemoglobin 7.5 ± 4.3%, lactate
dehydrogenase 617.8 ± 279.0 U/l, total bilirubin 24.9 ± 20.3 µmol/l, direct bilirubin 10.5 ±
12.0µmol/l, indirect bilirubin 14.4 ± 12.6 µmol/l, AST 45.9 ± 19.7 U/l, reticulocyte count 5.2

16

± 3.2% and irreversibly sickled cell count 6.1 ± 3.1%. A weak but significant positive
correlations were found between severity score and lactate dehydrogenase (r = 0.196; p =
0.032), aspartate aminotransferase (r = 0.215; p = 0.012) and total bilirubin (r = 0.229; p =
0.012). Lactate dehydrogenase levels differentiated individuals who had stroke (p = 0.008)
from those who did not have stroke and categorized stroke into the upper LDH quartile (i.e.
haemolysis associated phenotype). The other clinical presentations could not be categorized.
Haematological parameters measured showed no statistical difference between the LDH
quartiles (p > 0.05), while total bilirubin, direct bilirubin and indirect bilirubin showed a
significant difference (p = 0.004; 0.046; and 0.006) respectively.

The study concluded that the clinical phenotype of individuals with SCA in the steady state
using LDH levels was mixed, being a combination of both vaso-occlusion and haemolysis
associated clinical phenotypes. Stroke was the only clinical presentation that could be
categorized into the haemolysis-associated phenotype. The relationship between markers of
haemolysis and disease severity was weak and haematologic parameters measured could not
differentiate between the clinical presentations or severity of disease in these individuals.
Further studies using DNA analysis may be needed to distinguish between these individuals.