Blood pressure, body mass index and socio-economic status in the urban population of Antananarivo (Madagascar)

In many developing countries and especially those in the Indian Ocean, the prevalences of hypertension and obesity have increased markedly over the past decade. In a community-based study set in Antananarivo, the capital of Madagascar, multi-level modelling has now been used to look for associations between blood pressure or body mass index (BMI) and levels of occupation, education and income, among 773 adults. Many (23%) of the subjects had elevated blood pressure (i.e. over 140/90 mmHg). The prevalence of such elevated blood pressure increased with age - with an odds ratio (OR) of 2.16 and a corresponding 95% confidence interval (CI) of 1.81-2.58 for each 10-year increase - but decreased with educational level (high school: OR=0.74; CI = 0.41-1.31) and income (fourth quartile: OR= 0.66; CI = 0.35-1.27). The BMI data indicated that 18.4% of the subjects were underweight, 6.0% were overweight but not obese and 2.4% were obese. Being overweight was directly associated with level of occupation (management level: OR= 3.49; CI = 1.18-10.29) and income (fourth quartile: OR= 3.55;CI = 1.48-8.50). Despite the trends, underweight and overweight individuals and cases of elevated blood pressure were found to co-exist in all socio-economic classes.