In this study among adults in an urban East African setting, we noted a high prevalence of cardiovascular disease risk factors, including obesity, abdominal obesity, hypertension, dyslipidemia, diabetes mellitus, and metabolic syndrome. Several gender disparities in CVD risk factors were observed, with particularly high levels of obesity, abdominal obesity, and metabolic syndrome among women.
The prevalence of excess body weight was substantial in this study, particularly among women. This is consistent with findings from a previous study in Tanzania, which noted a high proportion of overweight among women aged 47 to 57 years [7
], and is consistent with other studies among women in urban areas in Cameroon and Kenya [5
]. The high proportions of overweight and obesity among women in the urban areas of Dar es Salaam may be attributed to socio-cultural factors, namely gender-specific patterns of work activities, sedentary lifestyle [25
], and cultural standard of physical attractiveness in African countries [26
Despite a high prevalence of overweight and obesity in this study, 53% of women perceived their weight as normal; 15% of them were actually obese and 16% had no intention of losing weight. Thus, the importance of weight loss and maintenance for prevention of cardiovascular disease and overall health may need to be emphasized and promoted in this population. This assumes greater importance in light of increasing prevalence of obesity among women in urban African settings [27
In this population we found an increasing trend of the prevalence of hypertension. Findings are consistent with previous studies in urban sub-Saharan African settings, and higher than previous reports in Tanzania. For example, in a study in Dar es Salaam in 2002, Bovet et al
] reported a prevalence of hypertension (BP ≥ 140/90 mmHg or anti-hypertensive (anti-HT) drug use) of 27% and 30%, among men and women respectively, compared to 51% and 42% in the current study (2006). Similarly, the prevalence of severe hypertension (BP ≥ 160/95 mmHg or anti-HT drug use) in our study was 30% and 29% in men and women, compared to 13% and 18%, as reported in the previous study in 2002 [28
]. The comparatively higher prevalence of hypertension in this study may be attributable to changes in dietary habits, socioeconomic status, sedentary lifestyle, and rates of obesity. However, we also observed 50% lower odds of hypertension among women compared to men, despite significantly higher rates of obesity. The comparatively lower rates of hypertension among women could be attributable to a protective effect of estrogen [29
], since 65% of women were pre-menopausal, and lower rates of smoking compared to a previous study in Tanzania [28
The association between increased body mass index and blood pressure is consistent with findings from previous studies in urban sub-Saharan African settings [10
]. Obesity is associated with increased cardiac output, total blood volume, and arterial resistance, in part due to the increased metabolic demand of excess body weight [30
]. In fact, at any given level of activity the cardiac workload is greater for obese individuals, with a corresponding increase in blood pressure [30
]. Previous studies have shown a relationship between obesity and high blood pressure; a 10 kilogram increase in body weight has been associated with a 3.0 mmHg higher systolic blood pressure and 2.3 mmHg higher diastolic blood pressure [30
In this study, women had significantly increased prevalence of obesity, but a reduced risk of hypertension. It is possible that increases in body fat mass may have different effects in women than in men, and that a greater degree of adiposity must be achieved in women to obtain a significant rise in blood pressure and an increase in a lipid risk profile comparable with that of men [31
]. Nevertheless, overall findings suggest that obesity is an important risk factor for hypertension and severe hypertension in urban Tanzania; cardiovascular disease prevention efforts should target reductions in excess body weight, through weight reduction/maintenance strategies.
We also reported the overall prevalence of metabolic syndrome of 38% in this population; more than 53% of women had metabolic syndrome. We are not aware of other studies in urban African settings, which are directly comparable to our findings; however, a similar high prevalence of metabolic syndrome has been noted in adults in the United States [32
]. Further research is warranted to examine the prevalence and components of metabolic syndrome in this population.
Some studies have shown a positive association of measures of adiposity with cholesterol, triglycerides, and LDL-cholesterol [33
], while a study in Nigeria did not demonstrate such a relationship [35
]. We observed a positive association between measure of obesity and components of the lipid profile in men, but not women. In particular, body mass index was associated with lower HDL-cholesterol, which is consistent with reports from previous studies [36
]. In addition, we did not observe significant gender difference on CVD risk factors, for the adjusted means of weight, WHR, cholesterol levels, and fasting glucose in this study. This could be due to the fact that for statistically significant changes in weight, WHR, lipids and glucose to occur, much greater changes in lifestyle are required.
The prevalence of smoking has been reported to be increasing in Tanzania [38
]. The prevalence of current smokers was lower in men (23%) and in women (3%) in our study compared to the 2002 study [38
], 27% and 5%, respectively. This may be due to the fact that there was a wider age range in the previous study of 35–64 years compared to ours which was 44–66, suggesting that more young people were included in the previous survey. In both studies women smoked less than men. Although smoking rates were comparatively lower in this study population, smoking remains an important risk factor for hypertension and cardiovascular disease and more prevention/cessation programs are warranted in this population.
From the point of view of prevention of non-communicable diseases, weight control is an important priority in both men and women. An estimated 70 of women with central obesity were at risk of developing hypertension in this population. The detrimental effects of excess weight, particularly central adiposity, on blood pressure and lipid profile – important CVD risk factors – need to be addressed. Strategies should focus on a healthy diet, increased physical activity, and weight reduction and maintenance. Interventions to reduce weight gain are particularly warranted among women, and should address social, cultural, and gender-specific aspects of weight gain. The WHO and International Society of Hypertension risk prediction charts for assessment of cardiovascular risk factors for prevention and control of cardiovascular disease in low and middle-income countries needs to be implemented in this population [4
Our study has several limitations. First, the cross-sectional sampling design does not allow inferences to be drawn with respect to the causal relationships among variables. Second, the study sample is only representative of adults residing in Temeke, and findings may therefore not be generalizable to Dar es Salaam and other urban African settings. Due to a limited sample size of 209, we cannot rule out that there may be additional gender-related differences that we did not have sufficient statistical power to detect. Despite these limitations, this study provides important data regarding the prevalence and correlates of gender-specific CVD risk factors among adults in an urban African setting.