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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 16  |  Issue : 2  |  Page : 89-93

Framingham risk assessment of metabolic syndrome patients at a tertiary hospital in Nigeria


Department of Clinical Pathology, Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria

Date of Web Publication18-Jan-2018

Correspondence Address:
Ifeyinwa Dorothy Osegbe
Department of Chemical Pathology, University of Nigeria, Nsukka; University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu State
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ajmhs.ajmhs_35_17

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  Abstract 


Background: Cardiovascular disease (CVD) is an increasingly important cause of morbidity and mortality worldwide. Combination of risk factors for CVD can be seen in the metabolic syndrome (MS), which can be computed to get an assessment of an individual's risk for future cardiovascular events. Aims: We aimed to determine the Framingham risk assessment of MS patients at the Lagos University Teaching Hospital, Nigeria. Materials and Methods: This was a cross-sectional study of newly diagnosed patients with MS using the International Diabetes Federation criteria. Anthropometry and clinical data were obtained, and fasting blood glucose and lipid concentrations were also determined. Framingham risk assessment was calculated and categorized as <10%: low risk, 10–20%: intermediate risk, and >20%: high risk for future CVD. Results: There were 120 patients (females 82, males 38) with mean ages of 52 ± 13.5 years and 54 ± 14.2 years, respectively (P = 0.46). Framingham risk assessment showed 56 (47%) patients comprising of 42 females and 14 males had low risk; 31 (26%) patients comprising of 24 females and 7 males had intermediate risk while 32 (27%) patients comprising of 16 females and 16 males had high risk for CVD. The risk assessment significantly correlated with age, systolic blood pressure, and total and high-density lipoprotein-cholesterol (P < 0.05). Conclusion: Majority of the males had high 10-year risk for CVD while most of the females had low risk. Men may need to intensify strategies to reduce modifiable risk factors for CVD.

Keywords: Cardiovascular disease, Framingham risk assessment, metabolic syndrome


How to cite this article:
Osegbe ID, Dada A, Soriyan O. Framingham risk assessment of metabolic syndrome patients at a tertiary hospital in Nigeria. Afr J Med Health Sci 2017;16:89-93

How to cite this URL:
Osegbe ID, Dada A, Soriyan O. Framingham risk assessment of metabolic syndrome patients at a tertiary hospital in Nigeria. Afr J Med Health Sci [serial online] 2017 [cited 2018 Apr 25];16:89-93. Available from: http://www.ajmhs.org/text.asp?2017/16/2/89/223582




  Introduction Top


Noncommunicable diseases such as cardiovascular disease (CVD) are an important cause of morbidity and mortality.[1] According to the global burden of disease study, current predictions estimate that by the year 2020, CVD, notably coronary heart disease (CHD), will become the leading global cause of total disease burden.[2]

Manifestations of CVD include CHD (myocardial infarction, angina pectoris, heart failure, and coronary death); cerebrovascular disease (stroke and transient ischemic attack); peripheral arterial disease (intermittent claudication and significant limb ischemia); and aortic disease (aortic atherosclerosis, thoracic aortic aneurysm, and abdominal aortic aneurysm).[3]

Risk factors have been identified for CVD and classified into nonmodifiable and modifiable risk factors depending on if they can be altered by lifestyle changes and/or pharmacotherapy.[4] Some of these factors can be seen in the metabolic syndrome (MS) such as abdominal obesity, elevated blood pressure, and fasting blood glucose as well as dyslipidemia.[5] Studies have shown that the combination of these metabolic abnormalities, as seen in MS, confers more risk for CVD than the presence of a single factor.[6],[7]

These risk factors can be computed to assess an individual's risk of developing CVD later in life,[8] of which the Framingham risk assessment score is an available tool.[9] The American College of Cardiology and American Heart Association have recommended assessing traditional risk factors for atherosclerotic CVD every 4–6 years in adults 20–79 years of age who are free from CVD and performing the CVD risk assessment every 4–6 years in adults 40–79 years of age without CVD.[10]

MS has a high prevalence in this environment. Ogbera reported a prevalence of 86% among participants attending some tertiary hospitals in Lagos.[11] Although MS has been found to be a significant predictor of CHD, it is not as good a predictor as the Framingham risk score.[12] Therefore, it will be beneficial to assess the risk of future CVD using this score in all patients at presentation. This will guide appropriate and adequate intensity of treatment strategies of risk factors to improve their risk score and thereby avert potential CVD. Therefore, the objective of this study was to determine the Framingham risk assessment of MS patients at the Lagos University Teaching Hospital (LUTH), South West Nigeria.


  Materials and Methods Top


Study design

This was a cross-sectional study of CVD risk assessment using Framingham risk scoring of adult patients with MS attending the metabolic medicine clinic of the LUTH, Idi-Araba, which is an 800-bed tertiary health institution in Lagos, South West Nigeria. The study protocol was reviewed and approved by the hospital's research and ethics committee.

Study population

Included participants were male and female adult patients aged 25–74 years who were newly diagnosed in the outpatient clinic with MS using the new International Diabetes Federation (IDF) definition as follows:[5] central obesity defined as waist circumference in females ≥80 cm and males ≥94 cm, plus two of the following four factors: (a) raised triglyceride ≥150 mg/dl (1.7 mmol/L) or specific treatment for the lipid abnormality; (b) reduced high-density lipoprotein-cholesterol (HDL-C) <40 mg/dl (1.03 mmol/L) in males and <50 mg/dl (1.29 mmol/L) in females; (c) raised systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥85 mmHg or treatment of previously diagnosed hypertension; (d) raised fasting plasma glucose ≥100 mg/dl (5.6 mmol/L) or previously diagnosed type 2 diabetes mellitus (DM). However, if body mass index (BMI) >30 kg/m 2, then central obesity was assumed and waist circumference did not need to be measured. Patients who had previous history of CVD were excluded from the study. All participants were recruited for the study after they were fully informed and consent obtained. Confidentiality was ensured.

Data collection

During the study period of 9 months, participants completed self-administered questionnaires to provide the following information: sex, age, history of DM, hypertension or use of antihypertensive medication, and cigarette smoking. Afterward, their blood pressure was taken in the sitting position after 5 min of rest using a digital sphygmomanometer on the left arm.

Specimen collection

Participants were requested to return in the morning after an overnight 10–12 h fast for antecubital venous blood collection. Five milliseconds of blood was drawn into a plain vacutainer for total cholesterol (TC) and HDL-C determination.

Specimen processing and analysis

The specimens were taken to the laboratory for processing. They were allowed to clot and retract for 30 min and then centrifuged at 4000 rpm for 10 min at room temperature, after which they were analyzed daily. Hemolyzed, icteric, and lipemic specimens were excluded from the study. Standard enzymatic methods were used to determine TC and HDL-C (Biolabo, France) and measured at wavelength 500 nm using a spectrophotometer (SM23A, England).

The results obtained were used to calculate the CVD risk score using the Framingham 10-year general CVD risk prediction equation and categorized as <10%: no risk, 10%–20%: moderate risk, and >20%: high risk for CVD.[9]

Statistical analysis

All data were entered into IBM SPSS Statistics version 20 (IBM Corp., Armonk, NY, USA) statistical package for analysis. Kolmogorov–Smirnov test was used to test for normality, and results for systolic blood pressure and percentage risk were log-transformed. Descriptive statistics were computed with standard methods and presented as mean (standard deviation [SD]) and counts (percentages). Pearson correlation between the Framingham score and the risk factors for CVD was performed, and the level of statistical significance was established at P < 0.05.


  Results Top


One hundred and twenty participants consisting of 82 (68.3%) females and 38 (31.7%) males were included in this study with mean ages of 52 ± 13.5 years and 54 ± 14.2 years, respectively (P = 0.46), of which all were obese BMI ≥30 kg/m 2.

Seventy-six (63.3%) participants – 53 females and 23 males – were receiving antihypertensive medication while 47 (39.1%) – 29 females and 18 males – were previously diagnosed with DM before presentation at the metabolic clinic. None (0%) of the participants claimed to smoke cigarettes. The mean ± SD values of glucose, TC, HDL-C, and systolic blood pressure are shown in [Table 1].
Table 1: Framingham cardiovascular disease risk factors and assessment

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Ten-year risk assessment for CVD using Framingham risk score showed median (interquartile range) of females n = 82, 9% (4%–16%) and men n = 37, 15% (7%–33.5%). One patient's risk score could not be calculated because it exceeded the equation's age limit of 30–74 years.[9]

Categorization of CVD risk showed that 56 (47%) patients were at low risk for CVD, 31 (26%) were at intermediate risk, and 32 (27%) were at high risk; of which, majority of females had low risk (42/82) and majority of males had high risk for CVD (16/37) [Table 2].
Table 2: Categories of cardiovascular disease risk assessment

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Pearson correlation between percentage risk assessment and risk factors for CVD was statistically significant with age, systolic blood pressure, TC, and HDL-C [Table 3]. An inverse relationship was observed with HDL-C.
Table 3: Framingham cardiovascular disease risk assessment (%) versus its risk factors

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  Discussion Top


The new IDF definition for MS was used for our participants because it is recommended for use in routine clinical practice as the measurement of insulin resistance is not required.[5] Furthermore, Can and Bersot showed that IDF definition has very good relationship with National Cholesterol Education Program Expert Panel On Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) and American Association of Clinical Endocrinologists criteria (kappa: 0.77–0.84).[13]

Framingham risk scoring includes the following variables: sex, age, systolic blood pressure, TC, HDL-C, DM, hypertension and/or its treatment, and cigarette smoking. Some of which are involved in MS. In this study, we observed that there was no statistical difference between all the mean values of these risk factors in the females versus the males despite the difference in number of participants (P > 0.05). Female preponderance was also reported by other Nigerian studies as 68% and 70.6%, respectively.[14],[15]

However, the 10-year CVD risk assessment among the females was significantly different from the males (P = 0.01). This was supported by findings derived from the Framingham Heart Study participants of lifetime risk for atherosclerotic CVD among participants free of CVD at 50 years, similar to our participant's mean age. They observed statistical difference in the risk predictions between males and females.[16]

We observed that majority of participants had low risk for future CVD, which is comparable to findings by Ogunmola et al.[14] However, we had a greater prevalence of high-risk assessment (27%) than they did (9.8%),[14] possibly because our participants had more risk factors for CVD.

Sex has an important role to play in CVD. Most of our males were categorized with high risk for CVD while most of the females were low risk. This has been similarly reported by other studies.[14],[17] Likewise, Dada et al. who studied only females reported that 44 (96%) of them with MS had a risk score of <10%, signifying low risk for CVD.[18] This observation may be explained by the cardiovascular protection rendered by estrogen in females.

According to the MS inclusion criteria, all our participants were obese, and we observed a high prevalence (63.3%) of hypertension among them. This was supported by a European study which reported that overweight and obesity are responsible for about 55% of hypertensive disease among adults in Europe.[19] Furthermore, a Nigerian study of hypertensive patients reported the prevalence of MS as 34.3% (ATP III), 35% (WHO), and 42.9% (IDF).[20]

Previously diagnosed type 2 DM patients were observed in 39.1% of our MS participants. Insulin resistance has been proposed as the key mechanism thought to underlie MS because hyperinsulinemia stimulates adipogenesis.[21] Edo and Edo reported that 26.2% of their type 2 DM participants were obese using BMI while abdominal obesity was observed in 41.5% of female and 23.1% of their male participants.[22]

There was a positive relationship between the CVD risk assessment and each of the risk factors, except with HDL-C which showed a negative relationship. This supports the knowledge that low serum HDL-C concentration is strongly and inversely associated with risk for CHD.[23] A 1% decrease in HDL-C has been associated with a 2%–3% increase in CHD risk.[23]

Cigarette smoking is an important contributor to the Framingham risk score, and the original cohort reported that 34.2% of females and 35.2% of males smoked cigarettes.[9] However, we recorded 0% for both sexes, probably because of the sociocultural background of the participants, as smoking is not common in the locality, further buttressed by the humid weather conditions that may make the habit uncomfortable.

The 10-year % CVD risk score correlated significantly with age, systolic blood pressure, TC, and HDL-C in our participants (P < 0.05). Achidi and Tangoh also observed a significant relationship between mean 10-year CHD absolute risk with age, gender, and alcohol consumption.[24]

Limitations

We did not randomly select our patients nor attempt to ensure a balanced female-to-male ratio but included all patients who fulfilled our inclusion criteria. This was to ensure all newly diagnosed MS patients benefitted from CVD risk assessment. Furthermore, the limited sample size was due to constraints in available resources. To better evaluate the contribution of modifiable and nonmodifiable risk factors to CVD risk assessment, we could have included a control group of individuals who lacked the risk factors for CVD, but that was beyond the scope of our objective.


  Conclusion Top


Risk assessment for future CVD events was determined among our MS patients using the 10-year general risk Framingham score. We observed that majority of females had low risk for future CVD while majority of the males had high risk. Since the male sex is an unmodifiable risk factor, men may need to mitigate the modifiable risk factors present to improve their risk scores.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Causes of Death 2008: Data Sources and Methods. Geneva: World Health Organization; 2011. p. 1-28. Available from: http://www.who.int/healthinfo/global_burden_disease/cod_2008_sources_methods.pdf. [Last accessed on 2017 Jul 25].  Back to cited text no. 1
    
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Hu G, Qiao Q, Tuomilehto J, Balkau B, Borch-Johnsen K, Pyorala K, et al. Prevalence of the metabolic syndrome and its relation to all-cause and cardiovascular mortality in nondiabetic European men and women. Arch Intern Med 2004;164:1066-76.  Back to cited text no. 7
    
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Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB, et al. Prediction of coronary heart disease using risk factor categories. Circulation 1998;97:1837-47.  Back to cited text no. 8
    
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D'Agostino RB Sr., Vasan RS, Pencina MJ, Wolf PA, Cobain M, Massaro JM, et al. General cardiovascular risk profile for use in primary care: The Framingham Heart Study. Circulation 2008;117:743-53.  Back to cited text no. 9
    
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Goff DC Jr., Lloyd-Jones DM, Bennett G, Coady S, D'Agostino RB, Gibbons R, et al. 2013 ACC/AHA guideline on the assessment of cardiovascular risk: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2014;129:S49-73.  Back to cited text no. 10
    
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Ogbera AO. Prevalence and gender distribution of the metabolic syndrome. Diabetol Metab Syndr 2010;2:1.  Back to cited text no. 11
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Can AS, Bersot TP. Analysis of agreement among definitions of metabolic syndrome in nondiabetic Turkish adults: A methodological study. BMC Public Health 2007;7:353.  Back to cited text no. 13
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Ogunmola JO, Olaifa OA, Akintomide AO. Assessment of cardiovascular risk in a Nigerian rural community as a means of primary prevention evaluation strategy using Framingham risk calculator. IOSR J Dent Med Sci 2013;7:45-9.  Back to cited text no. 14
    
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Oluyombo R, Olamoyegun MA, Olaifa O, Iwuala SO, Babatunde OA. Cardiovascular risk factors in semi-urban communities in Southwest Nigeria: Patterns and prevalence. J Epidemiol Glob Health 2015;5:167-74.  Back to cited text no. 15
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Dada AS, Ajayi DD, Areo PO, Raimi TH, Emmanuel EE, Odu OO, et al. Metabolic syndrome and Framingham risk score: Observation from screening of low-income semi-urban African women. Medicines (Basel) 2016;3. pii: E15.  Back to cited text no. 18
    
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Brandt L, Erixon F. The prevalence and growth of obesity and obesity related illnesses in Europe. European Centre for International Political Economy, 2013. ecipe.org/app/uploads/2014/12/Think_piece_obesity_final.pdf. [Last accessed on September 2017 Sep 01].  Back to cited text no. 19
    
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