ABO blood group and social class: a prospective study in a regional blood bank

ABO O gene frequency increase in the US might be causing increased maternal mortality

Maternal mortality rate has increased in the United States over the past 30 years from 16 deaths per 100,000 births to 28 deaths per 100,000 births while the rest of the world is experiencing declining rates. Increasing obesity and c-section rates in the US have been cited as contributing factors needing remediation, and because of the two to three fold difference in maternal mortality rates in non-Hispanic black women compared to white women, inequality and implicit racial bias has been targeted as well for remediation. Using an epidemiologic approach, a hypothesis here brought to bear is that US immigration policy changes over the past 50 years have brought changes in the gene pool that have caused increasing obstetric hemorrhage and other causes of maternal death. ABO gene frequencies have changed in the US during this time such that ABO O, a gene associated with hemorrhage and mortality in pregnancy, has increased in frequency in the US thus increasing population maternal mortality rate. Using mendelian randomization logic, noting the increase in ABO O gene in the US population over the past 30 years and the association of ABO O gene with both hemorrhage and lower longevity, the increase in frequency of the ABO O gene in the past 30 years in the US population might be causative of an increase in maternal mortality rate. Consequences of this hypothesis would include recognition of the role of ABO gene and thus ABO blood group in prediction of risk of obstetric hemorrhage. Thus those at risk on this basis would be under high surveillance and would have medications and treatment strategies readily available. While research on ABO gene and pregnancy has been done, much of the research is being done in countries other than the US, and given the increasing mortality in the US as well as the role that ABO gene may have in that, further research needs to be done in US populations to quantify risk for all adverse events in pregnancy related to ABO blood type including hemorrhage as well as inter-related causes including pre-eclampsia, cardiovascular disease, thromboembolic disease and infection.

Social mobility and health in the Turin longitudinal study

One of the most controversial explanations of class inequalities in health is the health selection hypothesis or drift hypothesis which suggests there is a casual link between the health status of individuals and their chances of social mobility, both inter- and intra-generational. This study tests this hypothesis, and tries to answer three related questions: (a) to what extent does health status influence the chances of intra-generational mobility of individuals? (b) what is the impact on health inequalities of the various kinds of social mobility (both mobility in the labour market and exit from employment)-do they increase or reduce inequalities? (c) to what extent does health-related intra-generational social mobility contribute to the production of health inequalities? The data analysed in this paper were drawn from the records of the Turin Longitudinal Study, which was set up to monitor health inequality of the Turin population by combining census data, population registry records and medical records. Occupational mobility was observed during the decade 1981-1991. To evaluate the impact of the various processes of social mobility on health inequalities, mortality was observed over the period 1991-1999. The study population consists of men and women aged 25-49 at the beginning of mortality follow-up (1991), and registered as resident in Turin at both the 1981 and the 1991 censuses (N = 127,384). Health status was determined by observing hospital admission. For the purpose of the study healthy individuals were those with no hospital admissions during the period 1984-1986, while those admitted were classed as unhealthy. Social mobility in the labour market was measured via an interval data index of upward and downward movements on a scale of social desirability of occupations, designed for the Italian labour force via an empirical study carried out by de Lillo and Schizzerotto (La valutazione sociale delle occupazioni. Una scala di stratificazione occupazionale per l'Italia contemporanea, Il Mulino, Bologna, 1985). Movement out of the labour market was described by a discrete variable with four conditions: employed, unemployed, early retired and women returning from work to the housewife status. The relationship between health status and occupational mobility was analysed via analysis of variance and multinomial logistic regression. Health inequalities were measured by the ratio of standardised mortality rates in the unskilled working class and the upper middle class. The study found a weak relationship between health status and occupational mobility chances. Decidedly stronger was the impact on occupational mobility of gender, education and "ethnicity" (being born in the South of Italy). The relationship between occupational mobility and health takes two different forms. Occupational mobility in the labour market decreases health inequalities; occupational mobility out of the labour market (early retirement, unemployment, housewife return) widens them. The maximum contribution health-related intra-generational social mobility can make towards health inequalities was estimated at about 13% for men.

ABO blood group and ischaemic heart disease in British men

OBJECTIVE

To establish whether ABO blood group is related to ischaemic heart disease on an individual and geographic basis in Britain.

DESIGN

Prospective study of 7662 men with known ABO blood group selected from age-sex registers in general practices in 24 British towns.

MEASUREMENTS

ABO blood group, standard cardiovascular risk factors, social class, and presence or absence of ischaemic heart disease determined at entry to study.

END POINTS

Eight year follow up of fatal and nonfatal ischaemic heart disease events achieved for 99% of study population.

RESULTS

Towns with a higher prevalence of blood group O had higher incidences of ischaemic heart disease. In individual subjects, however, the incidence of ischaemic heart disease was higher in those with group A than in those with other blood groups (relative risk 1.21, 95% confidence limits 1.01 to 1.46). Total serum cholesterol concentration was slightly higher in subjects of blood group A. No other cardiovascular risk factor (including social class) was related to blood group.

CONCLUSIONS

Blood group A is related to the incidence of ischaemic heart disease in individual subjects. Geographic differences in the distribution of ABO blood groups do not explain geographic variation in rates of ischaemic heart disease in Britain. The findings do not support the view that ABO blood group and social class are related.