Inequalities in health : social, biological, ethnic and life-course perspectives

There is an unmistakable consistency in differences in risks for morbidity and mortality between social groups. The more advantaged, whether measured in terms of income, education, class, status or ethnicity in general fare better when compared to others, emphasizing the importance of the social environment in determining health in all stages of life. The early stages of life; infancy, childhood, and adolescence are particularly vulnerable – exposures and health in these and later periods of life are dependent on both concurrent social environments and on previous parental life experiences and intergenerational influences. This stresses the need to investigate the development of risk factors and disease across the life course. Affluent and high-income countries are increasingly characterized by widening inequalities in health. Less is known about health differences in ethnic minorities in Sweden compared to similar high- income countries with large immigrant and ethnic minority groups.

The importance of intergenerational mechanisms and the psychosocial environment in predicting childhood health was highlighted in studies in this thesis. Children (aged 5-14 years) of parents with lower reported levels of physical activity, higher smoking and alcohol consumption had higher mean BMI and cholesterol levels, independent of parental socioeconomic indicators. Overweight/obese parents also had substantially higher risks for having overweight/obese children (compared to parents of normal BMI, an obese mother had an OR of 4.53 (95% CI 1.98–10.38) for having an overweight/obese child. Similarly, OR for obese fathers was 5.07 (95% CI 2.11–12.20)).

Results from studies included in this thesis show that some immigrant groups are at higher risk for health outcomes seen in different stages of the life course. Immigrant parents from Poland, Yugoslavia, Iran, South Asia, East Asia and Sub-Saharan Africa had higher risk for early preterm birth (adjusted RR (95% CI) 1.76, (1.24-2.50), 1.57, (1.31-1.87), 1.67, (1.30-2.14), 1.52, (1.07-2.16), 1.51, (1.08-2.10) and 2.03, (1.32-3.12)) respectively). South Asian, Sub-Saharan African and East Asian immigrant groups had a higher risk for late preterm birth (adjusted RR 1.62 (1.42-1.84), 1.31 (1.08-1.60) and 1.20 (1.06-1.36) respectively). North African/Middle eastern, Somali, and Ethiopian/Eritrean groups had increased RR for postterm birth (adjusted RR 1.31, (1.16-1.47), 2.57 (2.31-2.86), 1.85 (1.67-2.04) respectively). Children aged 4-5 years old, with immigrant parents from Turkey, North Africa, Iran and South America had a higher risk for overweight or obesity compared to children of Swedish born parents. In both studies, socioeconomic indicators did not explain the observed increased risk for either non-term birth or overweight/obesity indicating that other factors that constitute ethnicity may play a role. On the other hand, young Swedish males (ages 18 years) of immigrant parents had lower systolic blood pressure when compared to ethnic Swedish males. The established inverse association between foetal growth and adulthood blood pressure while observed in European-origin men was not seen in non-Europeans.

While evidence exists to support that certain ethnic groups suffer disproportionately in risk for some of the adverse health outcomes studied in this thesis, there is also an indication that some ethnic groups are protected from the same. Contrary to expectation, variation in socioeconomic indicators did not explain the observed differences in risk. More studies are needed to understand these observed differences in health and guide better public health intervention for reducing inequalities seen in ethnic minorities.

List of scientific papers

I. Khanolkar A, Vågerö D, Koupil I. Social determinants of cardiac disease biomarkers: investigating a Swedish male cohort at ages 50 and 70. Eur J Prev Cardiol. 2012 Jun; 19(3):523-33.
https://doi.org/10.1177/1741826711405952

II. Khanolkar AR, Byberg L, Koupil I. Parental influences on cardiovascular risk factors in Swedish children aged 5-14 years. Eur J Public Health. 2012 Dec; 22(6):840-7.
https://doi.org/10.1093/eurpub/ckr180

III. Khanolkar AR, Sovio U, Bartlett JW, Wallby T, and Koupil I. Socioeconomic and early life factors and risk of being overweight or obese in children of Swedish- and foreign-born parents. Pediatr Res. 2013 Sep; 74(3):356-63.
https://doi.org/10.1038/pr.2013.108

IV. Khanolkar AR, Wedrén S, Essén B, Sparén S, Koupil I. Preterm and postterm birth in immigrant- and Swedish-born parents: a national population register-based study. [Submitted]

V. Khanolkar AR, Wedrén S, Ploubidis G, Sparén S, Koupil I. Ethnic differences in the associations of foetal growth rate with BMI and systolic blood pressure in young adulthood. [Submitted]