Association of ABO blood group B with myocardial infarction.

OBJECTIVE The purpose of this study was to find out the association between blood group B and Myocardial Infarction (MI) in sample population in Malaysia. STUDY DESIGN A case-control study. PLACE AND DURATION OF STUDY The study was conducted at Hospital Kepala Batas, Penang, Malaysia, from 2006 to 2007. METHODOLOGY The study was approved by the Research and Ethics Committee, School of Medical Sciences, University Sains Malaysia. The study included 170 patients with confirmed MI as cases and 170 subjects without MI were taken as controls. After ethical approval, patients were recruited for the study from Hospital Kepala Batas after informed consent. Blood sample around 2 ml was collected from each patient and control. Each blood sample was tested by ABO gel card test for the blood group. Sample size was calculated using a power and sample size software, whereby power of study was 80%, Confidence Interval (CI) was 95%, odds ratio was 2 and ratio of control to case was 1. Odds ratio and the CI were used to describe the association between MI and group B. RESULTS A total of 170 MI patients and 170 controls were tested for ABO blood groups. Statistical analysis showed that among 170 MI subjects, 54 (31.8%) were blood group B and among 170 controls, 51 (30%) were blood group B. Simple logistic regression analysis showed no association of MI with blood group B (p=0.824, crude OR 0.95, 95% confidence interval 0.62-1.47). Multiple logistic regression analysis also did not show association of blood group B with MI (p=0.222, adjusted OR 0.68, 95% confidence interval 0.37-1.26). CONCLUSION This study failed to demonstrate any association of blood group B with MI in sample population in Malaysia compared to few studies reporting positive association, however, we suggest further studies to elaborate on this finding in Malaysian population.