Familial risk of premature cardiovascular mortality and the impact of intergenerational occupational class mobility.

The negative impact of low social class on cardiovascular disease (CVD) and mortality has been consistently documented. However, less scientific consistency exists in terms of whether a unique health effect of social mobility from childhood to adulthood prevails. This study explored how childhood and adult social class and the transition between them (social mobility), are related to premature CVD mortality when familial aggregation of CVD among siblings is also considered. The study includes nearly 1.9 million Swedish residents born 1939-1959 distributed over 1,044,725 families, of whom 14,667 died prematurely from CVD in 1990-2003. Information on parental class (1960) and own mid-life occupational class (1990) was retrieved from the respective censuses. Odds ratios for premature CVD mortality according to trajectory-specific social mobility, along with pairwise mean odds ratios for sibling resemblance of premature CVD mortality, were calculated by means of alternating logistic regression. This model calculates the remaining dependency of CVD mortality within sibships after accounting for available risk factors (like parental and adult social class) in the population mean model. Results showed that premature CVD mortality was associated with both parental and own adult social class. A clear tendency for the downwardly mobile to have increased, and for the upwardly mobile to experience a decreased risk of premature CVD mortality was found, as well as a corresponding unique effect of social mobility per se among the manual and non-manual classes. This effect was verified for men, but not for women, when they were analysed separately. The pairwise mean odds ratios for premature CVD mortality among full siblings were 1.78 (95% CI: 1.52-2.08), and were independent of parental CVD mortality and parental or adult occupational class.