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REVIEW Cardiovascular Disease as a Result of the Interactions Between Obesity, Climate Change, and Inflammation: The COCCI Syndemic Michael Clearfield, DO; Glenn Davis, MS; Jennifer Weis, DO; Gregory Gayer, PhD; Jay H. Shubrook, DO From the Touro University Obesity and climate change conspire to create an environment in which sub- College of Osteopathic clinical vascular inflammation leads to progressive atherosclerosis, which Medicine-CA in Vallejo. Drs Clearfield and Shubrook are contributes to the number 1 cause of global mortality: cardiovascular investigators in the National disease. The syndemic model requires 2 or more diseases or contributors to Institutes of Health fi Cardiovascular Inflammation disease (such as obesity and climate change) clustering within a speci c Trial. population in addition to the associated societal and social factors, ultimately Disclaimer: Jay H. Shubrook, creating an environment supportive of a greater adverse interaction. This an associate editor of The article explores the syndemic of obesity and climate change as a driver for Journal of the American cardiovascular disease. Osteopathic Association,was not involved in the editorial J Am Osteopath Assoc. 2018;118(11):719-729 review or decision to publish doi:10.7556/jaoa.2018.157 this article. Keywords: cardiovascular disease, climate change, inflammation, obesity Financial Disclosures: None reported. Support: None reported. Address correspondence to umerous breakthroughs in medicine and technology over the past half century Jay H. Shubrook, DO, Touro have addressed risk factors for and management of cardiovascular disease University College of (CVD); yet, despite these successes, CVD remains the number 1 cause of mor- Osteopathic Medicine-CA, N 1 1310 Club Dr, Mare Island, tality in both men and women. The evidence base for treating patients with major CVD Vallejo, CA 94592-1187. risk factors, such as hyperlipidemia, hypertension, and cigarette smoking, have resulted 2-5 Email: [email protected] in both robust improvements and national guidelines. Therapeutic and preventive inter- ventions have continued to improve cardiovascular (CV) outcomes, such that the most Submitted fi December 19, 2017; recent lipid-lowering trials have demonstrated continued bene ts from lowering low- accepted density lipoprotein cholesterol (LDL-C) to levels far below the targets elicited from January 17, 2018. current guidelines.6-10 However, even with the significant benefits associated with aggressive LDL-C lowering, there remains a considerable residual risk in both primary and secondary CV risk populations (Figure 1). Historical Perspective on CVD Cardiovascular disease steadily increased through the first half of the 20th century, peaking around 1968, when the annual growth flattened.11,12 Since that time, CVD mortality rates have decreased from 507/100,000 to 254/100,000—a 50% decrease; yet, given the growth of the population and especially people aged 65 years or older, CVD remains the number 1 cause of mortality.11 Had the trend from 1900 to 1968 continued, it is estimated that an additional 1 million CVD deaths likely would have occurred in 2014.12 The Journal of the American Osteopathic Association November 2018 | Vol 118 | No. 11 719 REVIEW 35 30 25 20 15 CV Event Rate, % 10 Placebo Treatment 5 0 IMPROVE IT FOURIER REVEAL JUPITER HOPE-3 Secondary Primary Achieved LDL: 53 mg/dL 30 mg/dL 38 mg/dL 55 mg/dL 88 mg/dL Figure 1. Residual cardiovascular (CV) risks in lipid-lowering trials persist despite low-density lipoprotein (LDL) lowering to levels below those generally recommended. Although beneficial, significant residual CV risk remains after therapy. Patients at primary risk have never had a CV event; patients at secondary risk have a CV event in their history. Abbreviations: FOURIER, Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk; HOPE-3, Heart Outcomes Prevention Evaluation–3; IMPROVE IT, Improved Reduction of Outcomes: Vytorin Efficacy International Trial; JUPITER, Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin; REVEAL, Randomized Evaluation of the Effects of Anacetrapib Through Lipid-Modification. CV Risk Factors factors: total blood cholesterol greater than or equal to Starting in the 1950s and then escalating into the 1960s 240 mg/dL, hypertension, BMI greater than or equal to was a concern over the steep rise in CV events and mor- 30, hemoglobin A1c greater than or equal to 6.5%, and tality in the United States. To that end, several public current smoker. These risk factors accounted for health initiatives contributed to the plateauing of CV approximately half of the deaths due to CV events in mortality, such as the Surgeon General’s 1964 report 2009-2010.16 Smoking and Health,13 the 1977 Report of the Joint After adjusting for the Behavioral Risk Factor National Committee on Detection, Evaluation, and Surveillance System CV risk factor cut-points, there Treatment of High Blood Pressure,14 and the 1988 remains considerable residual risk. Recent trials17-19 National Cholesterol Education Program Adult suggest that if more robust cut-points were implemen- Treatment Panel report,15 all of which recommended ted for these 5 CV risk factors, the residual risk would more aggressive approaches to CV risk factors. As a still persist, albeit further reduced. component of these guidelines, the traditional risk Other CV and metabolic risk factors include high factors of age, gender, total cholesterol and high- serum glucose, high triglyceride, and low HDL-C density lipoprotein cholesterol (HDL-C) levels, systolic levels. Individually, these risk factors have not demon- blood pressure, smoking history, and diabetes were strated similar significant CVD risk reductions as incorporated into the Framingham Risk Score and later found with LDL-C reduction, blood pressure lowering, in the Global Risk Assessment for Primary Prevention and cigarette smoking cessation and, therefore, have not to predict CV risk.2,15 Starting in 1984, the self- promulgated similar guidelines indicating therapeutic reported risk factor status from the Behavioral Risk targets for the management and/or prevention of Factor Surveillance System incorporated 5 CV risk CVD.20-22 720 The Journal of the American Osteopathic Association November 2018 | Vol 118 | No. 11 REVIEW Residual CV Risk and Table. Metabolic Syndrome Waist Circumference Criteria for Metabolic Syndrome27 In the Third Report of National Cholesterol Education Program Adult Treatment Panel III,23 the diagnostic cri- Waist fi teria for metabolic syndrome were de ned as the presence Criteria Circumference of at least 3 of the following 5 risk factors: abdominal ATP III, AHA, ACC obesity, elevated triglyceride level, decreased HDL-C Men ≥102 cm (40 in) level, elevated blood pressure, and elevated fasting Women ≥88 cm (35 in) glucose level. When the metabolic panel of glucose, tri- IDF (European, US, Canada, glycerides, and HDL-C are evaluated collectively for Middle Eastern, Sub-Saharan metabolic syndrome, the residual risk for CVD is African) 24 increased independent of body mass index (BMI). This Men ≥94 cm (37 in) increase in CVD risk with metabolic syndrome may Women ≥80 cm (31 in) fi explain, in part, the signi cant residual risk that remains, IDF (South Asian, Japanese, as shown in Figure 1, when traditional risk factors for Chinese, Ethnic South and Central Americans) CVD are improved.25,26 Additionally, when more than 3 ≥ of the metabolic syndrome risk factors are combined, Men 90 cm (35 in) there is a continuous trend of increasing CVD risk.25 Women ≥80 cm (31 in) Other risk factors, including insulin resistance, proin- Abbreviations: ACC, American College of Cardiology; AHA, flammatory state, and pro-thrombotic state, were also American Heart Association; ATP III, Adult Treatment Panel III; IDF, International Diabetes Federation. noted in the definition of metabolic syndrome but were not included in the diagnostic criteria because these risk factors could not be easily identified by routine clin- insulin sensitivity, absent of diabetes, dyslipidemia, or ical evaluation.23 However, these additional metabolic hypertension, and designated as metabolically healthy risk factors are most notably associated with obesity.23 obese (MHO).29-31 The definition of MHO varies somewhat, with the most common being overweight or obese without the presence of metabolic syndrome.31 Residual CV Risk and Obesity Using that definition, the prevalence of MHO generally The Canadian guidelines for the diagnosis and manage- ranges from 20% to 30% of the obese/overweight ment of dyslipidemia and the prevention of CVD, as population.24,29,31 well as those from the American College of Clinical Compared with metabolically healthy normal-weight Endocrinologists for management of dyslipidemia and people, metabolically healthy overweight and MHO prevention of CVD, have used the International people tend to progressively increase CV risk as their Diabetes Foundation (IDF) definition for metabolic weight increases when followed up for more than syndrome.27,28 In the IDF model, central obesity (waist 10 years.24,29 This finding suggests that an increase in circumference, 31 inches in women and 35-37 inches in residual CV risk may occur as weight increases in men, depending on ethnicity) is an essential criterion people who are MHO such that about half will transition and requires the addition of 2 of the other metabolic from metabolically healthy to unhealthy over the next risk