Relative protection from ischaemic heart disease in beta-thalassaemia carriers

To compare the frequency of beta thalassaemia trait in individuals with Ischaemic Heart Disease (IHD) and a control population without IHD.

Case control study.

Department of Haematology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from September 2007 to May 2009.

Using non-probability consecutive sampling, a total of 544 subjects were selected, including 272 IHD patients and an equal number of age and gender matched normal controls. The subjects were tested for the presence of ß-thalassaemia trait by performing their blood counts, haemoglobin electrophoresis and Haemoglobin A₂ (HbA₂) estimation. Proportions were compared using chi-square test. Odds ratio was also calculated.

The frequency of ß-thalassaemia trait was determined in IHD patients and was compared to the frequency in normal Pakistani population. Six out of the 272 control subjects (2.2%) had ß-thalassaemia trait and one of the control subject had Haemoglobin D trait. In contrast, none of the 272 IHD patients had ß-thalassaemia trait. The calculated odds ratio was less than 1, which shows a significant negative association of ß-thalassaemia trait with IHD. The difference in the frequency of ß-thalassaemia trait in the two groups was statistically significant (p=0.033).

The results suggest that ß-thalassaemia carriers have some protection against IHD, though it is not an absolute cardio protection due to the role of other risk factors in IHD. This beneficial information may be communicated to the concerned individuals in their counselling sessions and as part of general awareness on thalassaemia.