Metabolic syndrome indicators and target organ damage in urban active coping African and Caucasian men : the SABPA study / A. de Kock
MOTIVATION: The increasing prevalence of metabolic syndrome (MetS) is creating immense concern worldwide. In 2009, the International Diabetes Federation (IDF) announced the new MetS definition. MetS is diagnosed by any 3 of the following 5 indicators being present: increased waist circumference (WC), blood pressure (BP), triglycerides, and fasting glucose values, and decreased high–density lipoprotein cholesterol (HDL–C) concentrations. Psychosocial stress relating to an urban environment or acculturation greatly influences the prevalence of both MetS and target organ damage (TOD). Furthermore, in urban Africans, active coping (AC) responses have been associated more with MetS and the related cardiovascular pathology than avoidance. A further synergistic effect of MetS and AC responses was also revealed in African men, in strong association with both subclinical atherosclerosis and renal impairment. Microalbuminuria was four times higher in Africans with MetS, than in those without any MetS indicators. Furthermore, Africans, especially those utilising AC responses, present with greater carotid intima–media thickness (CIMT) than their Caucasian counterparts, although they exhibit a lipid profile that is anti–atherogenic. OBJECTIVES: The objectives were firstly to indicate and compare differences regarding AC responses in the African and Caucasian men, in accord with the prevalence of MetS indicators. Secondly, the extent to which AC responses and MetS indicators predict endothelial dysfunction was investigated. METHODOLOGY: This comparative target population study is nested in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study, which was conducted from February until the end of May in both 2008 (Africans) and 2009 (Caucasians), avoiding seasonal changes. The Ethics Committee of the North–West University approved the study, and all volunteers gave written informed consent prior to participation. Procedures were conducted according to the institutional guidelines of the Declaration of Helsinki. The participants included 202 male teachers of which 101 were African and 101 Caucasian. Ambulatory blood pressure (BP) measurements were recorded with the Cardiotens CE120 at 30 minute intervals during the day and 60 minutes at night. Actical accelerometers determined physical activity (PA). Registered clinical psychologists supervised completion of the psychosocial questionnaires, including the Coping Strategy Indicator. Participants fasted overnight; after the last BP recording, disconnection of the Cardiotens CE120 and Actical followed. A fasting 8 hour overnight collected urine sample was obtained from each participant. Anthropometric measurements followed, after which a registered nurse commenced blood sampling. The SonoSite Micromaxx was used for the scanning of CIMT. MetS indicators (glucose, triglyceride, and HDL–C), together with gamma glutamyl transferase, cotinine, and ultrahigh–sensitivity C–reactive protein (hs–CRP), were analyzed with Konelab 20i. The albumin–to–creatinine ratio and CIMT determined TOD. Participants were stratified according to ethnicity and median splits of AC response scores (high AC and low AC). Diabetic medication users (n= 8), and participants with renal impairment (n= 2) or HIV positive (n= 13), were excluded from analyses. 2×2 ANCOVA’s determined significant interactions for ethnicity and AC. Partial correlations between MetS indicators and TOD were performed within each ethnic and AC group, independent of age, alcohol consumption and PA. Regression analyses were performed for four models, firstly with microalbuminuria and secondly with CIMT as dependent variables. Significant values were noted as p 0.05, r 0.35, and adjusted R2 0.25. RESULTS: Caucasian men were physically more active than African men, whilst BP, alcohol consumption and hs–CRP levels were significantly higher in African men. Psychological variables revealed higher avoidance scores in Caucasian men and higher social support scores in African men. More MetS indicators exceeded the IDF cut–off points in high AC African men (14.71%) than in their Caucasian counterparts (3.33%). Furthermore, more MetS indicators predicted endothelial dysfunction in African men, especially the high AC responders. CONCLUSION: The following hypotheses were accepted: high AC responses in urban African men were associated with a higher prevalence of MetS indicators than in their Caucasian counterparts, while MetS indicators were associated with a marker of TOD in urban high AC African men, but not in their Caucasian counterparts.
- ETD@PUK