Individual and neighbourhood socioeconomic disparities and high blood pressure in France: Results from a cross-sectional analysis of the CONSTANCES cohort

Introduction The influence of socioeconomic status (SES) on cardiovascular outcomes has already been well-established. Lower income, lower education or manual occupation are associated with a higher prevalence of cardiovascular risk factors such as high blood pressure (HBP) as well as with cardiovascular mortality. Neighborhood factors, such as the affluence of the area of residence have also been associated with cardiovascular diseases. However, few studies have been able to analyze jointly the influence of individual and neighborhood SES on the prevalence of HBP. We aimed to do so using a large sample of French adults. Methods Participants are randomly selected adults aged 18 to 69 recruited to the CONSTANCES cohort between 2012 and 2015. Information on lifestyle was collected by a self-administered questionnaire. Blood pressure (BP) was measured in 16 recruitment centers using a standardized protocol. HBP has been defined as BP over 140/90 mmHg and/or taking antihypertensive medication as indicated by matched records from the national database or reimbursements from the French health insurance. SES has been defined at an individual-level using education and at a neighborhood-level through an indicator of socioeconomic deprivation of the area of residence (FDep), divided in quintiles in this study. Analyses were stratified by gender. We first calculated prevalence of HBP according to individual and neighborhood variables separately. We then performed three-level logistic regressions (recruitment center, neighborhood, individual) to analyze jointly the influence of individual and neighborhood SES on the prevalence of HBP, taking into account the specific structure of the data. Results A total of 63,627 individuals (53% women) recruited between 2012 and 2015 were included in the analyses. Mean age in men and women was 48.8 ± 13.3 years and 47.2 ± 13.5 years, respectively. In this sample, 19,383 individuals were classified hypertensive, so the crude prevalence of HBP was 30.5%. Using 2016 French population as reference, standardized prevalence of HBP was 27.5% [95% CI: 27.1–27.8], higher among men (33.8% [95% CI: 33.2–34.5%]) than women (21.3% [95% CI: 20.8–21.8%]). Prevalence increased with age, from 9.5% in 18–34 years to 63.5% in people aged 65 years and more. Prevalence of HBP strongly differed according to the education level in all age groups in both gender. For instance in women with no diploma, prevalence of HBP increased from 10% among 18–34 years to 65% among 65–70 years compared with 4% to 46% in women with highest diploma. The corresponding age-adjusted odds ratios (OR) for prevalence of HBP comparing the lowest versus highest level of education were 2.22 [95% CI: 2.00–2.50] in women and 1.82 [95% CI: 1.67–2.00] in men. Regarding neighborhood, living in more deprived areas was associated with a higher prevalence of HBP in women and men. Age-adjusted ORs for prevalence of HBP comparing the most versus least deprived quintile of areas of residence were 1.61 [95% CI: 1.47–1.75] in women and 1.69 [95% CI: 1.56–1.85] in men. In models including both individual and neighborhood indicators, OR comparing the lowest versus highest level of education were 2.09 [95% CI: 1.87–2.34] in women and 1.70 [95% CI: 1.53–1.88] in men. OR for prevalence of HBP comparing the most versus least deprived quintile of areas of residence were 1.25 [95% CI: 1.11–1.41] in women and 1.15 [95% CI: 1.03–1.30] in men. Conclusions In this cross-sectional analysis of a large sample of adults, we found marked socioeconomic gradients of HBP in all age groups and among both men and women. Individual and contextual indicators of SES were independently associated with the prevalence of HBP.