RESULTADOS CONCLUSIONES Y RECOMENDACIONES
MENORES DE 5 AÑOS ATENDIDOS EN EL CENTRO DE SALUD “B” 24 HORAS
Obesity has reached global epidemic proportions in both adults and children with estimated 1.1 billion adults worldwide being either overweight or obese.29 The increasing burden of obesity in the United States of America is said to be the driving force behind the rising prevalence of the metabolic syndrome and type 2 diabetes.3 Seventy percent of USA adults are obese.54 In the United Kingdom, obesity is said to be the rule amongst patients attending diabetes clinics with 86% of patients with type 2 diabetes being either overweight or obese.55
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In Cameroon the relatively higher prevalence of metabolic syndrome observed in the urban population was attributed to obesity.17 Also in the Republic of Benin, a cross-sectional study reported a positive rural-urban gradient for the prevalence of metabolic syndrome as follows;
rural 4.1%, semi-rural 6.4% and urban 11%. This gradient was also reflected in the pattern of abdominal obesity with prevalence’s of 28.2% in the rural, 41.5% in the semi-urban, and 52.5% in the urban communities. Other components of the syndrome did not reflect this ordered gradience.56
Ogbera working in Lagos with type 2 diabetics, observed that obesity was the commonest occurring metabolic syndrome defining parameter with a prevalence of 80%.57 Similarly at Ibadan, a high prevalence of obesity (86%) was reported in a type 2 diabetes study population.58
Children are not left out in this problem with the prevalence and magnitude of childhood obesity noted to be rising dramatically. The prevalence of metabolic syndrome was found to be high among obese children with reports of 38.7% observed in moderately obese children and 47.7% observed in severely obese children.59 Thus, the prevalence of the metabolic syndrome rises sharply with increasing adiposity. Obesity is gaining epidemic proportions and is basically driven by urbanization / westernization and the accompanying sedentary lifestyle and changing dietary habits. It is presumed that central obesity plays a key role in the development of the metabolic syndrome and may precede the appearance of the other components of the syndrome.
Although obesity has been traditionally defined as an increase in total body mass, it is visceral fat accumulation that is highly correlated with the cluster of metabolic abnormalities that make up the metabolic syndrome. Visceral adipose tissue depots are located in the body cavity beneath the anterior abdominal wall, in the greater and lesser omentum, the mesenteric
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fat and a lesser amount is located retroperitoneally. Visceral fat in comparison with subcutaneous fat represents a metabolically active organ, has a higher rate of lipolysis and is strongly related to insulin sensitivity.39 It causes a decrease in insulin-mediated glucose uptake especially in muscle. Abdominal fat has been linked with serious metabolic abnormalities such as insulin resistance, hyperinsulinemia, hypertriglyceridemia, hypertension and type 2 diabetes probably as a result of disruption of normal metabolic balance and increasing systemic inflammation.29 Also, obesity was found to be a significant independent predictor of cardiovascular diseases amongst participants of the Framingham Heart Study at long-term follow-up.60
Obesity may be assessed clinically in various ways including body weight, calculation of body mass index (BMI), waist circumference and waist-hip-ratio. Various arguments have arisen on the most ideal of these four measures in terms of determining metabolic risk. Waist circumference is accepted as an easily obtainable indicator of visceral adiposity and stronger correlations are noted between abdominal obesity and metabolic risk factors.7,33 Waist circumference was noted to have a continuous, graded and highly significant direct correlation with cardiovascular risk.29 Also, Brenner et al observed that waist circumference had a stronger association with dyslipidaemia, notably hypertriglyceridaemia, and HDL:Triglyceride ratio, than BMI.61 The NCEP-ATP 111 included waist circumference as a proxy measure of abdominal obesity stating that it is a better anthropometric predictor of metabolic risk factors than BMI.15
Body mass index is criticised for various reasons including; current cut-off values may under-estimate obesity and, it does not account for body fat distribution. But Reaven argued that though waist circumference may be a powerful predictor of clinical outcomes linked to insulin resistance, overall obesity as estimated by BMI, not only contributes to insulin resistance but also increases the likelihood that a person will develop the clinical syndrome
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associated with the defect in insulin action. He also adds that waist circumference and BMI are highly correlated and that one might not be superior to the other as either index of adiposity is equally predictive of differences in insulin action.40
However a large multi-national study in Europe noted that both general adiposity and abdominal adiposity were associated with the risk of death and support the use of waist circumference or waist-to-hip ratio in addition to BMI in assessing the risk of death.62 Of emerging interest is the place of waist-to-height ratio as a marker of CVD risk, the ideal waist being less than half of the height.29 This goal is said to be easily communicated to, and understood by patients and the general public. Whilst individual differences in the effects of increasing adiposity exist, weight gain worsens and weight loss improves insulin resistance in predisposed persons.47
Currently used waist circumference for adults is guided by the NCEP ATP-111 recommendation of <88cm for females, and <102cm for males but country specific waist circumferences values are recommended by the new harmonised guidelines and are being developed for various regions/ countries.15,28 No data has been released for Nigeria yet.
Body mass index (BMI) = Weight in Kilogram / (Height in meters)2 classification of obesity ;
Underweight < 18.5kg/m2
Normal 18.5 – 24.9 kg/m2
Overweight 25.0 – 29.9 kg/m2
Obesity I 30.0 – 34.9 kg/m2
Obesity II 35.0 – 39.9 kg/m2
Obesity III ≥ 40 kg/m2 (Extreme Obesity)
39 2.5.3 HYPERTENSION
Hypertension has a worldwide distribution and is said to affect approximately one billion people worldwide. As the population ages, the prevalence of hypertension increases further unless broad and effective preventive measures are implemented. The Framingham Heart Study suggests that individuals who are normotensive at age 55years have a 90% lifetime risk for developing hypertension.63 High blood pressure is a leading cause of death and disability causing 13.5% of the worlds premature death and 6% of its disability. Half of all strokes and ischemic heart disease can be attributed to high blood pressure.64
Hypertension, once rare in Africa, is emerging as a serious endemic threat. It has been referred to as the ‘silent killer’ as it often has no early detectable symptoms.65 Prevalence figures vary depending on demographic variables such as ethnicity, urbanisation, age, sex and presence of other co-morbidities notably diabetes mellitus and obesity. Sani et al , working with apparently healthy Nigerians at Katsina reported a hypertension prevalence of 25.7% in a mixed population.66 The economic burden of hypertension is further aggravated by the presence of the metabolic syndrome or other co-morbidities which significantly increase the cost of treatment and the added increase in risk of CVD.
The aetiology of essential hypertension is not fully understood but genetic factors, insulin resistance with compensatory hyperinsulinemia and obesity have been implicated.32,40,43,47
The link between hypertension and insulin resistance is demonstrated by three findings; a high percentage of patients with essential hypertension are insulin resistant and hyperinsulinemic, normotensive first degree relatives of patients with essential hypertension are more insulin resistant than marched control subjects without a family history of hypertension, and hyperinsulinemia has been shown to predict the eventual development of essential hypertension.40 But not all persons with hypertension are insulin resistant but it is
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those who are insulin resistant that are more likely to have the other components of the metabolic syndrome hence, the clustering.
With the prevalence of obesity increasing to pandemic proportions, a concomitant rise is observed with hypertension and other cardiovascular risk factors. There is a strong correlation of blood pressure with body weight and excess weight gain is highly predictive of subsequent hypertension.47,68 The GOOD (Global Cardiometabolic Risk Profile in Patients with Hypertension Disease) survey showed that blood pressure control was significantly worse in hypertensive patients with metabolic syndrome with or without diabetes mellitus than in those with essential hypertension alone. The findings suggest that other factors of the metabolic syndrome are likely to be responsible for this (notably central adiposity), further strengthening the hypothesis on the role of adipose tissue in the pathogenesis of hypertension.43,68
Hypertension is a well-recognised CVD risk factor and the relationship between blood pressure and risk of CVD event is continuous, consistent and independent of other risk factors. The higher the blood pressure, the greater the chance of heart failure, stroke and kidney disease.67 Hypertension is associated with both micro and macrovascular complications and tight blood pressure control in patients with hypertension and type 2 diabetes was associated with reduction in risk of deaths related to diabetes and the associated complications.69
According to the Seventh Report of the United States of America Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7), Hypertension is classified as:67
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Blood pressure classification Systolic Blood Pressure Diastolic Blood Pressure Normal <120 mm/Hg and <80mm/Hg
Pre-hypertension 120 – 139mm/Hg or 80 -89mm/Hg Stage 1 Hypertension 140 – 159mm/Hg or 90 – 99mm/Hg Stage 2 Hypertension ≥ 160mm/Hg ≥ 100mm/Hg
The JNC 7 report recommends target blood pressure in the non-diabetic population as less than 140/90mmHg. Diabetics have a lower target of less than 130/80mmHg. Also, in persons older than 50years, systolic blood pressure greater than 140mmHg is a much more important cardiovascular disease risk factor than the diastolic blood pressure and should be the main target for treatment. The new classification ‘Pre-hypertension’ was added to identify persons requiring health-promoting lifestyle modifications to prevent CVD.67