Socioeconomic differences in sympathovagal balance: the HELIUS study.

OBJECTIVE Alterations in sympathovagal balance are associated with cardiovascular disease. If sympathovagal balance differs across socioeconomic groups, it may reflect a mechanism through which disparities in cardiovascular disease occur. We, therefore, assessed the association between education and occupation with measures of sympathovagal balance in a large multi-ethnic sample. METHODS We included cross-sectional data of 10,202 South-Asian Surinamese, African Surinamese, Ghanaian, Turkish, Moroccan and Dutch origin participants from the HELIUS study. Sympathovagal balance was measured by baroreflex sensitivity (BRS) and the standard deviation of the interbeat interval (SDNN), calculated from changes in blood pressure and interbeat intervals, from 5 minute recordings. We calculated geometric means and estimated the relative index of inequality, using age and ethnicity-adjusted linear regression, to quantify the association between education and occupation and sympathovagal balance. Additionally, we assessed whether the association was consistent across ethnic groups. RESULTS The geometric means of BRS ranged from 8.16 ms/mmHg (CI=7.91-8.43) in low educated to 14.00 ms/mmHg (CI=13.53-14.48) in highly educated women, and from 8.32 (CI 7.97, 8.69) in low educated to 12.25 ms/mmHg (CI=11.86-12.66) in highly educated men. High education and occupation were statistically significantly associated with higher BRS and SDNN. Compared to the participants of Dutch origin, a pattern of weaker associations was found in the Surinamese and Ghanaian ethnic groups, but not the Turkish and Moroccan groups. CONCLUSION There is a clear socioeconomic gradient in measures of sympathovagal balance, indicating that sympathovagal balance may play a role in socioeconomic disparities in cardiovascular morbidity and mortality.