Évolution du risque cardiométabolique sur une période de quatre ans : étude chez des adultes béninois (Afrique de l’Ouest)

The objectives of this study on four-year trends (2006-2010) in cardiometabolic risk (CMR) in Benin adults were: • To examine whether abdominal obesity according to International Diabetes Federation (IDF) waist circumference cut-offs, or insulin resistance  measured by the homeostasis model assessment (HOMA) was associated with more unfavourable changes in other CMR factors,  • To examine the effects of diet, physical activity and socioeconomic status including place of residence on the evolution of CMR assessed by both the Framingham risk score for cardiovascular diseases (FRS) and the metabolic syndrome (MetS).  We hypothesized that: • Abdominal obesity as currently defined by IDF anthropometric criteria is weakly associated with unfavourable changes in other CMR factors while IR exacerbates other CMR factors in sub-Saharan Africans, • Medium income status, less urbanized place of residence (rural or semi-urban), physical activity and healthy eating patterns (higher score of consumption of foods that may protect against CMR) contribute to more favourable evolution of CMR.  The study included initially 541 apparently healthy adults aged 25-60 years and randomly selected in a large city (n = 200), a small town (n = 171) and its surrounding rural area (n = 170). After baseline survey, subjects were followed-up after two and four years. Dietary intake and physical activity were assessed by two or three 24-hour recalls in baseline studies and then by short frequency questionnaires at follow-ups. Data on alcohol intake and smoking patterns were collected in personal interviews. Anthropometric data, blood pressure, insulin resistance based on homeostasis model assessment (HOMA), blood glucose and blood lipids were measured. Education, income (proxy) and place of residence were the socioeconomic variables appraised in interviews. A food score based on consumption frequency of “sentinel foods” was developed and used. Complete data at last follow-up was available in 416 subjects. Baseline prevalence of MetS and FRS ≥ 10% was 8.7% and 7.2%, respectively. The incidence of MetS, and a FRS ≥ 10% over four years was 8.2% and 5%, respectively. The CMR deteriorated in 21% of subjects. Abdominal obesity as defined by IDF thresholds of the waist circumference was associated with a higher likelihood of insulin resistance: relative risk (RR) = 5.7 (CI 95%: 2.8-11.5), high total cholesterol/HDL-Cholesterol ratio: RR = 3.4 (CI 95%: 1.5-7.3). However, abdominal obesity was not associated with a significantly increased risk of high blood pressure or high triglycerides. In the study population, the optimal cut-offs of waist circumference that predicted at least one component of MetS were 90 cm in women and 80 cm in men. Insulin resistance measured by HOMA was associated with an increased risk of hyperglycemia: RR = 5.7 (CI 95%: 2.8-11.5). However, the insulin resistance was not associated with a significant risk of high blood pressure and high triglycerides.  The combination of MetS and the FRS depicted more at-risk subjects than the use of either tool alone. Diet and lifestyle mediated location and income effects on CMR evolution. Low “sentinel food” scores (foods that may reflect the protective effect of the diet against CMR): meat, poultry, milk and milk products, eggs and vegetables; and inactivity increased the likelihood of CMR deterioration: RR = 5.6 (CI 95%: 1.9-16.4) and RR = 6.3 (CI 95%: 3.0-13.4), respectively. Subjects with medium or low socioeconomic levels, and those living in the rural and semi-urban areas had a lower risk of CMR deterioration.  The study showed some differences in the relationship between abdominal obesity, insulin resistance and other CMR factors in Blacks compared to Caucasians and it also highlighted the need to reconsider MetS components and their cut-offs for sub-Saharan Africans. Combining MetS and FRS might be appropriate for surveillance purposes in order to better capture CMR. The results of the present study call for urgent measures to reduce CMR deterioration focusing on more active lifestyle and dietary inadequacies.

Keyphrases: Cardiometabolic risk factor changes, Nutrition transition, Chronic diseases, Abdominal obesity, Sub-Saharan Africa