Brief Communication Blood group distribution and life-expectancy: a single-centre experience Carlo Mengoli1, Carlo Bonfanti2, Chiara Rossi2, Massimo Franchini2 Department of Molecular Medicine, University of Padua, Padua; 2Department of Transfusional Medicine and Haemathology, Carlo Poma Hospital, Mantua, Italy 1
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Statistical analysis The mean age in females and males was compared by means of Student's t-test. The correlation between blood groups and gender was evaluated using Pearson's chi squared test on each of the O, A, AB and B groups. The changes of the frequencies of blood groups in various age groups were assessed with a test for trend, splitting the population by gender. The outcome was the odds of each blood group, where odds=P/(1-P), and P is the proportion of each blood group. The test computed a chi-squared test of homogeneity of odds (equal odds) and a test for linear trend of the log odds against the numerical code used for the categories of age. This investigation was applied to subjects between age 20 and age 99, comprising 26,788 observations. The same matter was investigated with a logistic approach, using each blood group frequency as a dependent variable, focusing on age as the main predictor, and adjusting for gender. The interaction age*gender was also added to the covariate list. The above age limits were maintained. All estimates were computed with Stata 13.1 software (StataCorp, College Station, TX, USA).
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The antigens of the ABO blood group system (A, B and H determinants, respectively) are complex carbohydrate molecules on the extracellular surface of red blood cells1. However, besides being expressed on red blood cells, ABO antigens are also strongly expressed on the surface of a variety of human cells and tissues, including the epithelium, sensory neurones, platelets, and the vascular endothelium2. The clinical significance of the ABO blood group system does, therefore, extend beyond transfusion medicine as several reports have suggested an important involvement in the development of cardiovascular, oncological and other diseases 3,4. In particular, a number of clinical studies and systematic reviews have documented a positive association between non-O blood type and the risk of developing both venous and arterial thrombotic events5-8. Although the underlying molecular mechanisms are not completely understood, ABO-related thrombosis is thought to be mediated by ABO carbohydrate modifications of von Willebrand factor (VWF) resulting in impaired proteolysis and higher levels of VWF, and consequently higher factor VIII plasma levels in individuals with a non-O blood type than in blood group O individuals9. Considering this association along with the finding that cardiovascular mortality is the first cause of death in men, it is not surprising that investigators have assessed whether ABO blood group correlates with life-expectancy10-12. However, as the investigations gave conflicting results, we decided to analyse such an association at our city hospital.
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Introduction
Material and methods
Population data A retrospective review of electronic clinical records was conducted for all subjects (outpatients and blood donors) who underwent ABO blood typing during the period from January 2010 to December 2013 at the Department of Haematology and Transfusion Medicine of Mantua. In all individuals evaluated, ABO blood type, age and gender were recorded. Age at the time of the observation was discretized into 11 age groups (0 to 10): age between 0-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89, 90-99, and >99 years.
Results
During the four-year study period, a cohort of 28,129 subjects presenting at our Institution as outpatients or as blood donors was collected. Of these subjects, 20,897 were female and 7,231 were males. The summary data of the population are reported in Table I. The subjects' ages spanned from 0 to 103 years. The mean age in females was 40.8 years whereas that in males was 57.2 years (p
iz
iS rl
Statistical analysis The mean age in females and males was compared by means of Student's t-test. The correlation between blood groups and gender was evaluated using Pearson's chi squared test on each of the O, A, AB and B groups. The changes of the frequencies of blood groups in various age groups were assessed with a test for trend, splitting the population by gender. The outcome was the odds of each blood group, where odds=P/(1-P), and P is the proportion of each blood group. The test computed a chi-squared test of homogeneity of odds (equal odds) and a test for linear trend of the log odds against the numerical code used for the categories of age. This investigation was applied to subjects between age 20 and age 99, comprising 26,788 observations. The same matter was investigated with a logistic approach, using each blood group frequency as a dependent variable, focusing on age as the main predictor, and adjusting for gender. The interaction age*gender was also added to the covariate list. The above age limits were maintained. All estimates were computed with Stata 13.1 software (StataCorp, College Station, TX, USA).
©
SI M
TI
Se
The antigens of the ABO blood group system (A, B and H determinants, respectively) are complex carbohydrate molecules on the extracellular surface of red blood cells1. However, besides being expressed on red blood cells, ABO antigens are also strongly expressed on the surface of a variety of human cells and tissues, including the epithelium, sensory neurones, platelets, and the vascular endothelium2. The clinical significance of the ABO blood group system does, therefore, extend beyond transfusion medicine as several reports have suggested an important involvement in the development of cardiovascular, oncological and other diseases 3,4. In particular, a number of clinical studies and systematic reviews have documented a positive association between non-O blood type and the risk of developing both venous and arterial thrombotic events5-8. Although the underlying molecular mechanisms are not completely understood, ABO-related thrombosis is thought to be mediated by ABO carbohydrate modifications of von Willebrand factor (VWF) resulting in impaired proteolysis and higher levels of VWF, and consequently higher factor VIII plasma levels in individuals with a non-O blood type than in blood group O individuals9. Considering this association along with the finding that cardiovascular mortality is the first cause of death in men, it is not surprising that investigators have assessed whether ABO blood group correlates with life-expectancy10-12. However, as the investigations gave conflicting results, we decided to analyse such an association at our city hospital.
rv
Introduction
Material and methods
Population data A retrospective review of electronic clinical records was conducted for all subjects (outpatients and blood donors) who underwent ABO blood typing during the period from January 2010 to December 2013 at the Department of Haematology and Transfusion Medicine of Mantua. In all individuals evaluated, ABO blood type, age and gender were recorded. Age at the time of the observation was discretized into 11 age groups (0 to 10): age between 0-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89, 90-99, and >99 years.
Results
During the four-year study period, a cohort of 28,129 subjects presenting at our Institution as outpatients or as blood donors was collected. Of these subjects, 20,897 were female and 7,231 were males. The summary data of the population are reported in Table I. The subjects' ages spanned from 0 to 103 years. The mean age in females was 40.8 years whereas that in males was 57.2 years (p
