The American Journal of Medicine (2007) Vol 120 (3A), S3–S11
Multiple Risk Factors for Cardiovascular Disease and Diabetes Mellitus Sidney C. Smith, Jr., MD UNC Center for Cardiovascular Science and Medicine, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA ABSTRACT In the past 25 years, obesity and diabetes mellitus have overtaken cigarette smoking, dyslipidemia, and hypertension as risk factors for coronary heart disease. Data from a Centers for Disease Control and Prevention (CDC) survey of 50 states revealed that, in 2000, the prevalence of obesity among US adults was approximately 20%, a 61% increase from the 1991 prevalence rate. Currently, most adults (ⱖ56%) are overweight, approximately 1 in 5 is obese, and 7.3% have diabetes. Overweight and obesity increase the risk for hospitalization and death from cardiovascular disease (CVD) and type 2 diabetes at all levels of risk and independently of other risk factors. In particular, abdominal obesity (assessed indirectly by measuring waist circumference) may be associated with clustering of cardiovascular and metabolic risk factors (i.e., hypertriglyceridemia, low high-density lipoprotein [HDL] cholesterol levels, high blood pressure, and elevated levels of fasting glucose) known as the metabolic syndrome. Patients with even minimal abnormalities in any 3 of the 5 risk factors for the metabolic syndrome are at heightened risk for CVD or diabetes. It is estimated that 47 million US adults, 25% of the population, have ⱖ3 metabolic syndrome components. Abdominal obesity is the most common, followed by low HDL cholesterol levels, high blood pressure, and high levels of triglycerides. The risk for disease increases over time as the number of metabolic syndrome characteristics accumulates; therefore, early intervention is warranted. Given the prevalence and potentially deadly consequences of the metabolic syndrome, it is imperative for physicians to recognize the presence of these risk factors in their patients and to familiarize themselves with the recommended treatment strategies. © 2007 Elsevier Inc. All rights reserved. KEYWORDS: Cardiovascular risk; Metabolic syndrome; Obesity; Type 2 diabetes mellitus
In the past 25 years, the prevalence of the so-called traditional risk factors for cardiovascular disease (CVD) (i.e., cigarette smoking, dyslipidemia, hypertension) has gradually declined in the United States. The area in which the greatest progress has been made is smoking cessation. In 1960, nearly 50% of the US population smoked, a prevalence rate that decreased to about 23% by 2000 (Figure 1).1 The reduction in the prevalence of these risk factors is at least in part attributable to the broader application of medical therapies to treat dyslipidemia and hypertension, and to aggressive advocacy and public policy programs to limit Requests for reprints should be addressed to Sidney C. Smith, Jr., MD, UNC Center for Cardiovascular Science and Medicine, University of North Carolina-Chapel Hill, 130 Mason Farm Road, Suite 4128, CB # 7075, Bioinformatics Building, Chapel Hill, North Carolina 27599. E-mail address: [email protected]
0002-9343/$ -see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.amjmed.2007.01.002
smoking in public places, ban cigarette advertising, and restrict the sale of tobacco to minors. Unfortunately, as smoking declined, the prevalence of obesity and diabetes mellitus dramatically increased. Data from the American Obesity Association (AOA) indicate that an estimated 127 million adults in the United States are overweight and 60 million are obese.2 The reasons for the increase in obesity appear to be multifactorial and are associated with a more sedentary lifestyle, a higher dietary intake of simple carbohydrates, and the emergence of insulin resistance. Currently, surging rates of obesity and diabetes threaten to offset the hard-won survival benefits associated with the reduction in traditional risk factors. It also has been speculated that poor diet and physical inactivity may soon overtake tobacco as the leading cause of death in the United States3 and that the consequences of obesity may
S4 lead to a decline in life expectancy in the United States in the 21st century.4 These trends are not limited to the United States but appear to be occurring worldwide in association with changes in lifestyle that involve “supersized” dietary intake and decreased physical activity.5,6 The current pandemics of obesity and diabetes in the United States and worldwide will undoubtedly increase the risk for CVD. Healthcare professionals are ideally positioned to assume a proactive role in counseling patients on weight and lifestyle issues and in advocating for public policies designed to promote healthy lifestyle choices (e.g., school and workplace cafeterias that offer healthy meal choices, transportation alternatives that facilitate walking and bicycling, and programs that encourage physical activity in schools and workplaces). The same strategies used by healthcare providers and public health officials that have proved successful in reducing the prevalence of traditional risk factors, such as smoking, should be applied to the reduction of nontraditional risk factors for type 2 diabetes and CVD.
EPIDEMIOLOGIC TRENDS IN OBESITY, METABOLIC AND CARDIOVASCULAR RISK Population-based data from the United States and the United Kingdom document a trend toward an explosive increase in obesity and type 2 diabetes that parallels the decline in traditional coronary heart disease (CHD) risk factors and threatens to erode CHD survival gains.
United States In the United States, the prevalence rates of obesity and diabetes reached near-epidemic proportions between 1991 and 2000, as documented by the Behavioral Risk Factor Surveillance System (BRFSS).7–10 The BRFSS was organized by the Centers for Disease Control and Prevention (CDC) to provide state-specific estimates of behaviors that relate to the leading causes of death.7 Data were collected through a cross-sectional standardized telephone survey of noninstitutionalized adults aged ⱖ18 years.7–10 The data on weight and diagnosed diabetes were self-reported and, therefore, probably underestimate the true prevalence of obesity and diabetes, particularly because individuals tend to underestimate their weight and overestimate their height, and many persons with diabetes remain undiagnosed.9,10 The 2000 BRFSS was based on responses from 184,450 participants in 50 states and was compared with data from previous surveys.10 Data from the BRFSS revealed that, in 2000, the prevalence of obesity had reached 19.8% among US adults, which reflects a 61% increase from the 1991 prevalence rate.9,10 In just 1 year (1998 to 1999), the prevalence of obesity increased from 17.9% to 18.9%, an increase of 5.6%, and 57% from 1991.8 For every kilogram increase in self-reported weight, diabetes increased by approximately 9%.7 It seems that not only are Americans growing fatter every year, but they are also increas-
The American Journal of Medicine, Vol 120 (3A), March 2007 ing their risk for diabetes and CVD. The prevalence of diabetes increased to 6.9% in 1999, a 6% increase in 1 year.11 Obesity begets diabetes, as illustrated by the close parallel between rising rates of obesity and type 2 diabetes during the 1990s (Figure 2).7–11 These staggering rates of obesity and diabetes are not confined to isolated geographic pockets. Every US region is in the grip of a twin epidemic of obesity and diabetes. In 1991, only 4 of the participating states had obesity rates of ⱖ15%, whereas by 2000, all participating states except Colorado had rates of obesity ⬎15%.9,10 The prevalence of obesity continues to climb each year, with rates of ⱖ20% becoming common. In 1991, no states had obesity rates of ⱖ20%; however, by 2000, 22 states had obesity rates that reached this level.9,10 The increased prevalence of type 2 diabetes paralleled that of obesity. The prevalence of self-reported diagnosed diabetes increased from 4.9% in 1990 to 7.3% in 2000.7,10 In 1990, 4 states had diabetes rates of ⱖ6%, whereas by 2000, 43 of 50 states had such rates.10 In 2000, Mississippi had the highest rates of obesity (24.3% of the population) and of diabetes (8.8%).10 The nation was sedentary throughout the decade, with rates of physical inactivity that remained unchanged. In 1991, 1998, and 2000, 28.4%, 28.2%, and 28.2% of participants, respectively, did not engage in physical activity on a regular basis.9,10 These findings indicate that, within a 9-year period during the 1990s, there was a steady increase in obesity and diabetes throughout the United States.10 Currently most adults (⬎56%) are overweight, approximately 1 in 5 is obese, and 7.3% have type 2 diabetes. If these trends continue at the present rate, it will place an enormous strain on existing healthcare resources at the state and national levels. Although both obesity and diabetes are preventable, only 42.8% of obese participants who were trying to lose weight had been advised to do so by a healthcare professional; only 15.6% of overweight participants had received such advice.10
United Kingdom Using the previously validated and updated IMPACT mortality model to combine and analyze data on utilization and effectiveness of cardiology treatments and risk factor trends,12–15 a group of British researchers sought to explain the reasons for the decline in CHD mortality observed in England and Wales between 1981 and 2000.12 The model incorporated data for men and women 25 to 84 years old that included (1) CHD patient numbers, (2) utilization of specific medical and surgical treatments, (3) population trends in major cardiovascular risk factors, (4) effectiveness of specific cardiology treatments, and (5) effectiveness of specific risk factor reductions.12 The results showed that, during this period, CHD mortality rates decreased by 62% in men and by 45% in women, resulting in 68,230 fewer deaths in 2000.12 Approximately 40% of the decrease in CHD risk was due to the combined
Multiple Risk Factors for CVD and Diabetes
Figure 1 Prevalence of cardiovascular disease risk factors in US adults (1961–2000). Hypertension is defined as blood pressure ⱖ140/90 mm Hg or current use of antihypertensive medication; high total cholesterol is defined as ⱖ240 mg/dL (ⱖ6.21 mmol/L); and overweight is defined as body mass index ⱖ25 (kg/m2). (Reprinted with permission from NHLBI/NIH Fact Book for Fiscal Year 2002, p. 50).1
Figure 2 The parallel between worsening trends of diabetes mellitus and obesity in the United States. (Adapted from JAMA8 –10 and Diabetes Care.7,11)
effects of modern cardiologic treatments and almost 60% to reductions in major risk factors, primarily smoking.12 Medical and surgical interventions accounted for 42% of the decrease. The role of specific interventions in decreasing risk was as follows: secondary prevention (11%), various heart failure treatments (13%), initial treatments of acute myocardial infarction (MI) (8%), and hypertension (3%).12 However, the largest contribution to risk factor reduction was attributable to smoking cessation, which decreased risk by 48%, followed by decreases in blood pressure (9.5%) and total serum cholesterol (9.6%).12 Clearly, physician efforts to implement primary and secondary prevention strategies had succeeded in reducing traditional risk factors for CHD mortality.
However, the good news about control of traditional risk factors was blunted by a disturbing trend toward the emergence of obesity, physical inactivity, and diabetes as increasingly prevalent CHD risk factors.12 The combination of these risk factors caused an additional 7,650 CHD deaths.12 The prevalence of obesity increased by 186%, resulting in an estimated additional 2,095 CHD deaths.12 Simultaneously, diabetes prevalence increased by 66%, causing an additional 2,888 CHD deaths, and indirect evidence suggested a 30% decrease in physical activity was responsible for 2,662 additional deaths.12 Overall, the triple threat of obesity, diabetes, and physical inactivity contributed to about 8,000 additional deaths in 2000, and the increase in these risk factors “canceled out 2 decades of improvement in cholesterol.”12
The American Journal of Medicine, Vol 120 (3A), March 2007
Midlife body mass index and risk for coronary heart disease and diabetes mellitus in older age. (Adapted from JAMA.16)
Clinical Implications of Obesity In the individual case, as opposed to on the population level, the long-term outlook for overweight and obese patients is discouraging and, therefore, mandates early intervention on the part of healthcare providers to prevent such common complications as CHD, CVD, and diabetes. Recently published data from the Chicago Heart Association Detection Project in Industry study established that obesity in middle age increases the risk for hospitalization and mortality from CHD, CVD, and diabetes in older age (ⱖ65 years).16 This prospective study examined the relation of body mass index (BMI) earlier in life to morbidity and mortality in older age among individuals with and without other risk factors.16 The study population of 17,643 men and women aged 31 to 64 years was recruited from 1967 to 1973 and was followed for a mean of 32 years.16 Participants were stratified into 5 baseline CVD risk categories (low, moderate, intermediate, elevated, and high) and 3 weight groups (normal, BMI 18.5 to 24.9 [kg/m2]); overweight, BMI 25.0 to 29.9; and obese, BMI ⱖ30.0).16,17 The results showed that overweight and obesity greatly compromised health status at all levels of risk. Multivariate analyses adjusted for systolic blood pressure and total cholesterol level showed the odds ratio (95% confidence interval) for CHD death for obese participants compared with those of normal weight in the same risk category was 1.43 (0.33– 6.25) for low risk and 2.07 (1.29 –3.31) for moderate risk.16 For CHD hospitalization, the corresponding results
were 4.25 (1.57–11.5) for low risk and 2.04 (1.29 –3.24) for moderate risk. The results were similar for other risk groups and for CVD but stronger for diabetes (e.g., low risk 11.0 [2.21–54.5] for mortality and 7.84 [3.95–15.6] for hospitalization). Once again, a strong correlation was demonstrated between obesity and diabetes. At every level of risk ranging from low to high, the presence of obesity increased the likelihood of mortality.16 The relative impact of obesity was stronger for individuals in the lower risk category compared with higher risk categories.16 Compared with CHD and CVD, the impact of overweight and obesity on diabetes was stronger and statistically significant for almost all risk categories (Figure 3).16 Obesity emerged as an independent risk factor in that elevated risk was present for individuals both with and without other major cardiovascular risk factors (i.e., smoking, high blood pressure, and/or high serum total cholesterol in young adulthood and middle age).16 Simply being obese increased an individual’s risk of dying from heart disease and/or diabetes. These results further underscore the fact that obesity is a major public health problem associated with a reduction in life expectancy similar in magnitude to that associated with smoking.16,18 Physicians should not accept weight gain in adulthood as a benign normal part of aging, even in the absence of other risk factors. Instead, overweight and obesity should prompt immediate clinical concern and aggressive evaluation for cardiovascular and metabolic risk.
Multiple Risk Factors for CVD and Diabetes
Table 1 National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) identification of the metabolic syndrome* Risk Factor Abdominal obesity (waist circumference) Men Women Triglycerides HDL cholesterol Men Women Blood pressure Fasting glucose
⬎102 cm (⬎40 in) ⬎88 cm (⬎35 in) ⱖ150 mg/dL (ⱖ1.69 mmol/L) ⬍40 mg/dL (⬍1.03 mmol/L) ⬍50 mg/dL (⬍1.29 mmol/L) ⱖ130/ⱖ85 mm Hg ⱖ100 mg/dL (ⱖ5.55 mmol/L)
HDL ⫽ high-density lipoprotein. *Diagnosis of the metabolic syndrome requires ⱖ3 of the 5 characteristics. Abdominal obesity is more highly correlated with metabolic risk factors than is increased body mass index. Adapted with permission from Circulation.19
THE METABOLIC SYNDROME: A CLINICAL CRITERION FOR CARDIOMETABOLIC RISK Obesity, and particularly visceral obesity (a type of obesity evidenced clinically by increased waist circumference),19,20 has been shown to correlate with heightened risk for the clustering of the following non–low-density lipoprotein (LDL) cholesterol risk factors19,21: (1) hypertension, (2) insulin resistance with or without impaired fasting glucose, (3) hypertriglyceridemia, (4) proinflammatory state, and (5) prothrombotic state. The combination of hypertriglyceridemia, small LDL cholesterol particles, and low high-density lipoprotein (HDL) cholesterol is referred to as the lipid triad.21 Its presence, along with nonlipid risk factors (e.g., hypertension, insulin resistance, and a proinflammatory and prothrombotic state) comprise the metabolic syndrome21 and increase the risk for CVD and diabetes.19 In 1988, Reaven22 first described the clustering of cardiometabolic risk factors currently known as the metabolic syndrome, termed it Syndrome X, and postulated insulin resistance as its underlying cause. Since that time, debate has continued about whether the metabolic syndrome is a true syndrome, and the extent to which insulin resistance is its driving force.23 Reflecting this controversy, various names have been used to describe it, including prediabetes, syndrome X, the deadly quartet, insulin resistance syndrome, dysmetabolic syndrome, and metabolic syndrome. However, debate notwithstanding, few would argue that the combined occurrence of these factors—also termed cardiometabolic risk factors—is a significant clinical problem and one associated with approximately a 2-fold increase in cardiovascular events and a 4-fold increase in the development of diabetes. In 2001, the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) recognized the growing importance of the risk factor clustering frequently
S7 associated with obesity, and codified the concept of the metabolic syndrome into clinical guidelines for the identification of patients at increased risk for CVD and diabetes.24 The diagnostic criteria for the metabolic syndrome are the presence of ⱖ3 of 5 specific risk factors (Table 1).19 The majority of patients with the metabolic syndrome have abdominal obesity and, significantly, compared with increased BMI, abdominal obesity is more closely correlated with metabolic risk.19,20 Therefore, the first, and simplest, step in establishing a diagnosis is to measure the patient’s waist. Moreover, in the current criteria, the threshold for prediabetes (impaired fasting glucose) has been lowered to ⱖ100 mg/dL from ⱖ110 mg/dL [1 mg/dL ⫽ 0.05551 mmol/L] to reflect the stricter cutoff point recently established by the American Diabetes Association (ADA). Results from the San Antonio Heart Study suggest that the lower the fasting glucose cutoff, the better the power of the NCEP ATP III metabolic syndrome to predict diabetes risk.25 Although considered part of the syndrome, measurements of proinflammatory and prothrombotic states have not been included as part of the official clinical definition.26 Patients with any 3 of the 5 risk factors for metabolic syndrome are considered to be at increased risk for the development of CVD or diabetes. Yet, in the clinical situation, many patients who meet the diagnostic criteria for the metabolic syndrome are overlooked. For example, a female patient with a blood pressure of 145/87 mm Hg, an HDL cholesterol level of 47 mg/dL, and a triglyceride level of 170 mg/dL would qualify for a diagnosis of the metabolic syndrome. It is important to recognize that even minimal elevations in ⱖ3 of these risk factors significantly increase cardiovascular and metabolic risk and warrant therapeutic intervention.
Prevalence of the Metabolic Syndrome The metabolic syndrome is an emergent clinical problem of monumental proportions, particularly in light of the rising epidemic of obesity. It is estimated that 47 million US adults, 25% of the population, have ⱖ3 of the metabolic syndrome traits.27 Data analysis of 8,814 male and female participants in the Third National Health and Nutrition Examination Survey (NHANES III) showed that the prevalence of the metabolic syndrome ranged from 6.7% among those age 20 to 29 years to ⱖ42% in those ⬎60 years.27 Using NCEP ATP III criteria, the prevalence of the various components of the metabolic syndrome among this representative sample of noninstitutionalized adults is delineated in Table 2.27 Estimates of high fasting glucose would have been higher than 13% if the modified cutoff ⱖ100 mg/dL had been used.19,27 Abdominal obesity was the most prevalent characteristic, occurring in 38.6% of those with metabolic syndrome.27 Low HDL cholesterol, high blood pressure (or medication use), and hypertriglyceridemia were also highly prevalent in 37.1%, 34.0%, and 30.0% of participants, respectively.27 Alarmingly, 71.2% of participants had ⱖ1 and 43.9% had ⱖ2 metabolic syndrome traits. This raises the question of
S8 whether early intervention, when patients present with 1 or 2 risk factors, might prevent the development of the fullblown syndrome. For example, simply advising a patient with 1 trait, abdominal adiposity, to lose weight might prevent the development of insulin resistance, as well as other risk factors.
PREDICTIVE VALUE OF THE METABOLIC SYNDROME Studies have shown that the metabolic syndrome is a clinically reliable entity for predicting the risk for cardiac events and diabetes. In a multivariate analysis of 10,357 NHANES III participants, cardiovascular risk clustering was shown to increase the risk for MI to a substantially greater extent than any individual risk factor alone (Table 3).28 Among the individual components of the metabolic syndrome, insulin resistance (defined by the older cutoff of fasting glucose ⱖ110 mg/dL), hypertriglyceridemia, and hypertension were independently and significantly related to MI and stroke.28 These findings suggest that the metabolic syndrome is a useful clinical entity for helping clinicians identify those patients at increased risk for MI and stroke28 and implement appropriate preventive strategies. The West of Scotland Coronary Prevention Study (WOSCOPS) used a modified NCEP ATP III definition in which BMI was substituted for waist circumference.29 The results showed that men with 4 or 5 components of the metabolic syndrome had a 3.7-fold increase in CHD risk and a dramatic 24.5-fold increase in diabetes compared with men with none (both P ⬍0.0001).29 Thus, the metabolic syndrome is correlated even more strongly with diabetes risk than with CHD risk, particularly when 4 or 5 components are present.29 The sum of risk factors is greater than its individual parts, as the risk for each disease increases as the number of metabolic syndrome traits accumulates. Timely intervention is crucial because once impaired glucose tolerance manifests, the conversion rate to diabetes is so high that it may be too late for preventive management.29 Also, lowering the glucose cutoff improved the prediction of both CHD and diabetes risk, and identified a greater number of men with the metabolic syndrome.29 The value of waist circumference over BMI in predicting type 2 diabetes may require adjustment by ethnic group.29 –31 The risks associated with the metabolic syndrome appear to worsen over time. A prospective Finnish cohort study of 1,209 men aged 42 to 60 years at baseline and followed for approximately 11.4 years showed that the presence of ⱖ3 risk factors over 10 years significantly increased CVD mortality (Figure 4).32 These findings demonstrate that the metabolic syndrome is associated with increased mortality, even in its early phases before the development of CVD or diabetes.32 The strong correlation of metabolic syndrome with CVD and diabetes over time, coupled with the increase in mortality, supports the rationale for early identification, treatment, and prevention of metabolic syndrome components, such as obesity.
The American Journal of Medicine, Vol 120 (3A), March 2007 Table 2 Prevalence of each component of the metabolic syndrome in US adults aged ⱖ20 years (1988 –1994) according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria Component
Abdominal obesity Hypertriglyceridemia Low HDL cholesterol High blood pressure or medication use High fasting glucose* or medication use ⱖ1 ⱖ2 ⱖ3
39% 30% 37% 34% 13% 71% 44% 24%†
HDL ⫽ high-density lipoprotein. *Fasting plasma glucose ⱖ110 mg/dL (ⱖ6.1 mmol/L). †Of 47 million US residents. Reprinted from JAMA.27
Table 3 Association of self-reported myocardial infarction with the metabolic syndrome and individual syndrome components
Metabolic syndrome Syndrome components Abdominal obesity High triglycerides Low HDL-C Hypertension Insulin resistance*
1.15 1.51 1.41 1.42 1.25
0.86–1.54 1.04–2.20 1.03–1.95 0.94–2.15 0.92–1.71
0.3475 0.0311 0.0353 0.0947 0.1461
CI ⫽ confidence interval; HDL-C ⫽ high-density lipoprotein cholesterol. *Fasting plasma glucose ⱖ110 mg/dL (ⱖ6.1 mmol/L). Reprinted from Circulation.28
EXPANDING THE CLINICAL DEFINITION OF METABOLIC SYNDROME The addition of proinflammatory and prothrombotic biomarkers to the current metabolic syndrome criteria might help to further define the population at high risk for CVD and diabetes. High sensitivity C-reactive protein (hs-CRP), an easily measurable biomarker of inflammation, adds to the prognostic value of the metabolic syndrome at all levels of severity.33 An 8-year follow-up study of 14,719 initially healthy women revealed that, in those with ⱖ3 metabolic syndrome components, elevated hs-CRP (⬎3 mg/L) was associated with even greater risk (P ⬍0.001) (Figure 5).33 Among the 24% of women with the metabolic syndrome at baseline, age-adjusted incidence rates of future CVD events per 1,000 person-years of exposure were 3.4 for those with normal hs-CRP levels (⬍3.0 mg/L) compared with 5.9 for those with elevated hs-CRP levels (⬎3 mg/L).33 In WOSCOPS, hs-CRP levels were also higher (P ⬍0.0001) in men with the metabolic syndrome compared with men with-
Multiple Risk Factors for CVD and Diabetes
Figure 4 Risk for cardiovascular disease mortality and the metabolic syndrome among individuals in a Finnish cohort study. CI ⫽ confidence interval; RR ⫽ relative risk. (Reprinted with permission from JAMA.32)
Figure 5 C-reactive protein (CRP), the metabolic syndrome, and the risk for future cardiovascular events in a cohort of 14,719 women. (Reprinted with permission from Circulation.33)
out it.29 Thus, hs-CRP measurement appears to add important prognostic information. A prothrombotic state, characterized by increased plasminogen activator inhibitor–1 (PAI-1) and fibrinogen, is also associated with the metabolic syndrome.19 Excess adipose tissue generates PAI-1, as well as other factors (e.g., cytokines, nonesterified fatty acids, adiponectin) that promote metabolic risk.19 Fibrinogen, an acute-phase reactant like hs-CRP, increases in response to cytokine production. Metabolically, prothrombotic and
proinflammatory states may be interrelated.19 In lieu of specific drugs that target PAI-1 and fibrinogen, antiplatelet therapy with low-dose aspirin is generally recommended.19
Cardiovascular and Metabolic Risk Assessment and Management A recently issued statement from the ADA and the American Heart Association (AHA) called for a joint effort from
S10 members of both organizations to identify and treat cardiovascular and metabolic risk factors (prediabetes, hypertension, dyslipidemia, and obesity).34 Several algorithms for estimating CVD risk have been proposed. However, most have not been validated outside the specific study populations on which they were based. A notable exception (and one recommended in the ADA/AHA statement) is a risk assessment tool (accessible at no cost on the Internet at http://www.diabetes.org/diabetesphd) that has been validated across multiple and diverse clinical trials and includes every known risk factor.34 Although providers should routinely assess patients for CVD and diabetes risk, few do so using risk assessment algorithms. Yet, even identifying easily quantifiable risk factors such as blood glucose level, blood pressure, LDL cholesterol level, tobacco use, and obesity may be enough to facilitate appropriate preventive management of diabetes and CVD risk. Finally, risk factor management through therapeutic lifestyle intervention (i.e., weight reduction and moderate physical activity) may be implemented and monitored in clinical practice.34 Obesity, in particular, is an obvious biomarker of underlying risk that should be addressed as a serious rather than merely cosmetic problem.34 Risk factor assessment and management is effective. If cardiovascular and metabolic risk factors are recognized in its early stages, lifestyle modification alone may be sufficient to prevent disease progression. In the later stages, pharmacotherapy (often involving polypharmacy) is indicated. Clearly, a concerted multispecialty effort is required to prevent the increasing prevalence of diabetes and obesity from eroding the hard-won survival gains of past decades.
SUMMARY Population-based data show a trend toward an epidemic increase in obesity and diabetes, which parallels the decline in cigarette smoking and other traditional risk factors (i.e., dyslipidemia, hypertension for CHD).7,9,10,12 In 2000, the prevalence of obesity among US adults reached 20%, with 22 of the 50 states surveyed reporting obesity rates at this level and 43 reporting diabetes rates of ⬎6%.10 Obesity increases the risk for hospitalization and death from CVD at all levels of CVD risk and independent of other risk factors.16 In particular, abdominal obesity acts as the driving force for insulin resistance and risk factor clustering, known as the metabolic syndrome. An estimated 47 million US adults have the metabolic syndrome.27 If the current trends continue, the costs of treating end-stage cardiovascular and metabolic disease will place an enormous strain on the healthcare system. Efforts are under way to define the optimal combination of behavioral and medical therapies for these patients; early intervention appears warranted. Research is also being conducted to better understand the mechanism by which visceral adiposity may contribute to the occurrence of clustered risk factors and the subsequent development of CVD or diabetes. Given the expanding dimensions of the epi-
The American Journal of Medicine, Vol 120 (3A), March 2007 demic of obesity and the widespread occurrence of cardiovascular and metabolic risk, it is imperative that the practicing physician be alert to the presence of these risk factors among patients and become familiar with the recommended treatment strategies.
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