Clinical and laboratory factors associated with splenic dysfunction among patients with sickle cell disease in a malaria endemic region.

BACKGROUND: Although loss of splenic function is the expected natural course for individuals with sickle cell disease (SCD), factors such as high HbF and coexistence of alpha thalassemia may ameliorate this process. We evaluated factors associated with two surrogate markers of spleen dysfunction, namely Howell-Jolly bodies (HJBs) and argyrophilic inclusion (AI) red cell counts, among patients with SCD. METHODS: Cross-sectional data of 182 patients with SCD (median age 11 y; 1-45 y) and 102 normal controls (median age 12 y; 1-32 y) were evaluated. Blood tests including full blood count, serum chemistry and high-performance liquid chromatography were performed. The HJB and AI red cell counts were performed on peripheral blood smears. RESULTS: The percentages of HJB and AI red cells rose significantly with increasing age in the SCD group. On regression analysis, the frequency of HJB red cells associated positively with mean corpuscular hemoglobin (MCH) (ß=0.289; p=0.001) and negatively with HbF (ß=-0.259; p=0.002). The AI red cell counts also associated positively with MCH (ß=0.321; P=0.001) and negatively with HbF (ß=-0.242; p=0.020). CONCLUSIONS: Data from this study indicate that the negative association of HbF with both markers of splenic dysfunction among our patients with SCD residing in a malaria endemic region is similar to findings elsewhere of its ameliorating effect on splenic dysfunction.

Determinants of splenic preservation among patients with sickle cell disease in North-Eastern Nigeria.

OBJECTIVE: In patients with sickle cell disease (SCD), the spleen commonly enlarges during early childhood, but undergoes reduction in size and fibrosis from repeated episodes of vaso-occlusion and infarction. The rate of progression of this process varies markedly among these patients. The aim of current study was to explore clinical and laboratory factors associated with the preservation of the spleen among these patients. METHODS: Two hundred four patients with SCD (103 females; age 1-45 years) underwent abdominal ultrasonography at the University of Maiduguri Teaching Hospital, Nigeria between October 2020 and November 2021 to assess for splenic visualisation and echotexture. Steady-state clinical parameters and blood samples for full blood count, serum chemistry, high-performance liquid chromatography and malaria parasitemia were obtained from all the patients. RESULTS: The spleen was visualised in 107 (52.4%; 95% confidence interval [CI], 46%-59%) patients with SCD on ultrasonography. While the spleen was visualised in all children less than 5 years of age, it was visualised in only 23.5% of those aged 15 years and older. Visualisation of the spleen was significantly associated with low mean corpuscular haemoglobin concentration and high haemoglobin F (HbF) in those younger than 10 years. The odds of visualisation of the spleen on ultrasonography increased by a factor of 1.17% for every 1% increase in HbF level. Only 32 (15%) patients were on regular hydroxyurea therapy. The HbF level was significantly higher among patients on hydroxyurea (median 12.7 vs. 7.4; p < 0.0001). CONCLUSION: In patients with SCD, failure to visualise the spleen was not found in children less than 5 years old. Patients with visualised spleens had a higher level of HbF than those with non-visualised spleens. HbF was significantly associated with visualisation of the spleen before 10 years of age. Since early administration of hydroxyurea will increase HbF level, we expect that it would help to preserve the spleen.

Evaluation of two red cell inclusion staining methods for assessing spleen function among sickle cell disease patients in North-East Nigeria.

The loss of splenic function is associated with an increased risk of infection in sickle cell disease (SCD); however, spleen function is rarely documented among SCD patients in Africa, due partly to the non-availability of sophisticated techniques such as scintigraphy. Methods of assessing splenic function which may be achievable in resource-poor settings include counting red blood cells (RBC) containing Howell Jolly Bodies (HJB) and RBC containing silver-staining (argyrophilic) inclusions (AI) using a light microscope. We evaluated the presence of HJB-and AI-containing RBC as markers of splenic dysfunction among SCD patients in Nigeria. We prospectively enrolled children and adults with SCD in steady state attending outpatient clinics at a tertiary hospital in North-East Nigeria. The percentages of HJB-and AI-containing red cells were estimated from peripheral blood smears and compared to normal controls. There were 182 SCD patients and 102 healthy controls. Both AI- and HJB-containing red cells could be easily identified in the participants blood smears. SCD patients had a significantly higher proportion of red cells containing HJB (1.5%; IQR 0.7%-3.1%) compared to controls (0.3%; IQR 0.1%-0.5%) (P <0.0001). The AI red cell counts were also higher among the SCD patients (47.4%; IQR 34.5%-66.0%) than the control group (7.1%; IQR 5.1%-8.7%) (P < 0.0001). The intra-observer reliability for assessment of HJB- (r = 0.92; r2 = 0.86) and AI- containing red cells (r = 0.90; r2 = 0.82) was high. The estimated intra-observer agreement was better with the HJB count method (95% limits of agreement, -4.5% to 4.3%; P = 0.579).We have demonstrated the utility of light microscopy in the assessment of red cells containing-HJB and AI inclusions as indices of splenic dysfunction in Nigerian SCD patients. These methods can be easily applied in the routine evaluation and care of patients with SCD to identify those at high risk of infection and initiate appropriate preventive measures.