Socioeconomic inequality in blood pressure and its determinants: cross-sectional data from Trinidad and Tobago

We evaluated income- and education-related inequalities in blood pressure, hypertension and hypertension treatment in the general population of Trinidad and Tobago. The design included survey of 300 households in north central Trinidad, including 631 adults in 2001. Measurements of blood pressure, weight, height, waist and hip circumferences, and educational attainment, household income and alcohol intake by questionnaire. The slope index of inequality (SII) was used to estimate the difference in blood pressure between those with highest, as compared to lowest, socioeconomic status. Complete measurements and questionnaires were obtained for 461 (73%) including 202 men and 259 women. In women, after adjusting for age and ethnicity, the SII for systolic blood pressure by income was -12.6, 95% confidence interval -22.6 to -2.6 mmHg (P=0.013); and -10.8 (-21.4 to -0.2) mmHg (P=0.045) by educational attainment. After additionally adjusting for body mass index, waist-hip circumference ratio and self-reported diabetes, the SII for income was -7.3 (-16.5 to 1.9) mmHg (P=0.120) and for educational attainment was -3.0 (-13.0 to 6.9) mmHg (P=0.551). In men, after adjusting for age and ethnicity, the SII for systolic blood pressure by income was -4.3 (-15.4 to 6.8) mmHg (P=0.447) and for education -8.1 (-19.0 to 2.8) (P=0.145). There is a negative association of systolic blood pressure with increasing income or education in women. This is associated with body mass index, abdominal obesity and diabetes. There is no consistent association between education or income and blood pressure in men.