Neonatal screening for haemoglobinoapathies at Muhimbili National Hospital Dar es salaam, Tanzania

Abstract

Background: Neonatal screening for abnormal haemoglobins has been reported as an important intervention in early detection and prompt management for those who are significantly affected and those who are carriers. If associated with clinical care programmes, they have proven to be an important measure at decreasing mortality and morbidity in many regions, as well as providing genetic counselling to parents who are contemplating having children. Objectives: To determine the frequency of occurrence and types of abnormal haemoglobins in neonates attended at Muhimbili National Hospital, Dar es Salaam. Materials and Methods: A hospital based cross sectional design was used to recruit neonates attended at MNH from September to November 2009. Eligible neonates were consecutively enrolled after their parents provided informed consent for participation. A structured interview proforma was used to collect information while blood specimens were drawn into EDT A with microgard closure tubes from a heel prick under aseptic techniques. Blood specimens were analysed by HPLC to determine abnormal haemoglobins in whole blood; Alkaline Hb electrophoresis as a second line (confirmatory) test for positive results from HPLC; and ABX PENTRA 60 for haematological parameters (CBC) analysis were used. SPSS version 16.0 was used for data analysis. Results: A total of 2,053 neonatal samples (mean age = 1.2 ± 0.5 days and 55.4% males) were analyzed. The frequency of occurrence of abnormal haemoglobins was found to be 18.2% (n=374). The types of abnormal haemoglobins included 12.6% (n=258) with sickle cell trait (Hb FAS); 5.3% (n=109) with possibly a-thalassaemia (Hb Barts); 0.9% (n=19) as sickle cell carrier or Hb S Bcta-thalassacmia (Hb FSA); 0.54% (n=ll) had SCA or Hb S BetaO-thalassaemia (Hb FS); and one had Hb FA-D variant. The frequency of occurrence of abnormal haemoglobins were highest among 35.6% (n=133) and 10.2% (n=38) of participants whose parents origins were reported from Costal Region and Lake Zone respectively, while 6.7% (n=25) of participants from the Northern Region of Tanzania had the lowest frequency of occurrence (X2 = 37.7, P < 0.01).

Vlll Presence of Hb Barts increased by nearly six times the likelihood of MCV being less than 100 f1 in 78.2% (n=68) of participants compared to 14%(n=206) without Barts (X2 =2.3, p<O.Ol); and increased by 1.3 the likelihood of low birth weight in 33.9% (n=37) compared to 25.4% (n=493) of those without Barts (X2=7.1 p<0.05). Conclusion: The frequency of occurrence of abnormal haemoglobins amongst neonates participated in the study is high and therefore it may be considered as major public health problem. There are other Hb variants such as Hb Bart, FSA and Hb-D variant which exist amongst study population in addition to FS and F AS which were previously known. Recommendations: Neonatal screening for abnormal haemoglobins should widely be implemented to allow for early identification and opportunities for comprehensive care. Molecular tests to confirm abnormal haemoglobins detected during screening programme should be emphasized. Larger neonatal cohort studies to generalize the findings of this screening pilot are also recommended.