Clinical Feature: Central Obesity and Southeast Asians

Chances are that each of us has and takes care of patients from Southeast Asia. This ethnic group is growing significantly in the United States. According to 2010 census data, while the U.S. population grew almost 9.7% between 2000 and 2010, the Asian population alone increased by more than four times that rate—by 43% in that 10-year period.¹

By definition, "Asian" refers to a person having origins in any of the original peoples of the Far East, Southeast Asia or the Indian subcontinent, including Cambodia, China, India, Japan, Korea, Malaysia, Pakistan, the Philippine islands, Thailand and Vietnam.²

Mr. P., 44, presented to his primary care physician’s office in September 2010 for a physical exam. His parents emigrated from India to the United States. His family history reveals a history of early cardiovascular disease in the family. He admits to smoking for several years when he was in his 20s but not currently. The only medication or over-the-counter supplement that he takes on a regular basis is krill oil—a friend told him it was good for his heart and overall health. He also admits to an occasional glass of wine. His job involves sitting at a desk the majority of the time, and he admits to very little activity or exercise. His vital signs reveal a height of 68 inches and a weight of 162 lbs. His BMI is 24. His waist circumference is 36 inches. His BP is 120/76. The rest of his vital signs are within normal ranges for age and sex.

 
Figure 1

An exam is performed and unremarkable, other than some slight abdominal or midsection fat (Figure 1). Labs reveal: Fasting total cholesterol, 199; triglycerides, 435; HDL-C, 33; non-HDL-C, 166; TSH, 1.8; and glucose, 109. LDL-C was not done secondary to elevated triglyceride levels. A quick calculation of his risk factors showed the presence of both family history and low HDL-C. At this visit he was given extensive counseling regarding diet, exercise and weight loss. He also was advised to follow up in three to six months for repeat assessment and laboratory testing.

Mr. P returns for follow-up in 2012—2 years later—and says he has been working on diet and exercise. He is more physically active now than his previous visit, trying to get out and walk at least twice weekly. In the interim since his last visit, he went to India to visit family. While there, he had lab work performed. He brings in a copy of his lab report for his provider to review. Total cholesterol, 159; HDL-cholesterol, 39; triglycerides, 198; LDL-cholesterol, 89. He is very pleased by these results. He says his "bad cholesterol" is less than 100, which is "at goal." His physician, having attended National Lipid Association meetings, knows he likely is harboring residual risk that is not apparent through standard lipid profiles and, therefore, orders additional laboratory testing, including an advanced lipid profile: total cholesterol, 189; LDL-cholesterol, 86; HDL-cholesterol, 35; non-HDL-cholesterol, 154; LDL-particle number, 1879; apoB, 108; glucose, 139; and Hg A1c,7.2. He is now overtly diabetic, based on his Hg A1c and glucose levels. In addition, he now has multiple risk factors—age, an early family history of cardiovascular disease, diabetes mellitus (considered a coronary heart disease risk equivalent) and low HDL-cholesterol. Both his apoB and LDL-p values indicate a discordantly high level of risk as compared to his LDL cholesterol.

This case is illustrative of commonly seen metabolic patterns in patients of Southeast Asian ancestry—significant percentages have high triglycerides and low HDL-cholesterol.³ In addition, the standard waist circumference charts that we use as one of the criteria to help define metabolic syndrome in the U.S. populations is different in people of Southeast Asian ancestry—this according to the International Diabetes Federation.^4-7 Their position advocates that different cut points should be used to define central obesity in this population (Table 1). What most clinicians in the United States use are the National Cholesterol Education Project (NCEP)/Adult Treatment Panel III criteria of 102 cm (40 inches) in men and 88 cm (35 inches) in women. It has been proposed that, in Southeast Asian patients, cut points of 90 cm (35 inches) for men and 80 cm (31.5 inches) for women be used to define central obesity—see Figure 1. Even more stringent guidelines have been proposed in Japanese men.

In Indians, specifically, mortality rates secondary to CVD have increased while decreasing in western countries.⁸ In addition, this population also has a higher prevalence of premature coronary artery disease.^9-11 A number of studies indicate that traditional risk factors do not explain fully the associated increased risk in Asian Indians.^12-13 Rates of hypertension are lower in Indians when compared to whites. In addition, total cholesterol and LDL-cholesterol are lower among Indians than whites. Data suggest that only 9% of Indians had HDL-cholesterol >50 mg/dL compared to more than 70% of black and white patients. In addition, triglyceride levels tend to be much higher in Indians than in either blacks or whites. It is thought that this so called "atherogenic dyslipidemia" is responsible for the increased risk of cardiovascular disease present in Indians not truly captured by traditional risk factors of elevated total cholesterol and LDL-cholesterol that pertain to either white or black populations.¹⁴ A recent study demonstrated that, among blacks and whites, a TG: HLD-C ratio >3 was associated with a substantially higher proportion of people with a BMI >25. In Indians, BMI was only modestly associated with a TG: HDL-C ratio >3. In the literature, TG: HDL-C ratios of >3 have been demonstrated to signify a higher likelihood of insulin resistance or presence of the metabolic syndrome.¹⁵ So, even slightly increased amounts of central obesity can be associated with insulin resistance and its subsequent problems in the Southeast Asian population.

Table 1

The reason(s) for racial differences in lipids and lipoproteins in Asian Indians is not clearly elucidated. It has been postulated that a diet high in carbohydrates and low in polyunsaturated fatty acid may contribute to high triglyceride levels, along with the tendency for Southeast Asians to be less physically active than other populations.¹⁶ Genetics likely also play a factor—the hepatic lipase gene has been hypothesized as a possible factor.^17-18

When Mr. P first presented to the practitioner, he had two traditional NCEP/ ATP III criteria: 1) an early family history of cardiovascular disease and, 2) low HDL-cholesterol. Since he had two risk factors, Framingham risk scoring was done. Calculating this score gave Mr. P a score of 5, which translated to a 10-year calculated risk of 2%. Based on that score, it would not be recommended that he have any pharmacologic treatment; instead, he would have only lifestyle counseling because he fell into a “low risk” group for future cardiovascular events, at least over the next 10 years. We believe, based on his initial elevated non-HDL-cholesterol and then clearly demonstrated later by his advanced lipoprotein testing, that he had a tremendous amount of future cardiovascular risk ahead of him and deserved aggressive treatment.

In summary, there are a number of issues to keep in mind when evaluating patients from India, specifically, or Southeast Asia in general. When you see these patients in your office, keep in mind that lower cutoffs of waist circumference need to be used to define the metabolic syndrome. These cutoffs are >/= 90 cm (35.4 inches) for men and >/= 80 cm (31.5 inches) for women in this population. If present, at least consider the possibility of insulin resistance and its commonly associated dyslipidemia patterns.

Another point to consider is that, in patients from Southeast Asia, total cholesterol and LDL cholesterol may not be the best "first glance" indicators of risk in these patients. As Mr. P demonstrated, his risk was substantial but not really captured by his total cholesterol. His initial LDL cholesterol could not be calculated, but subsequent values were "normal" and falsely reassuring. When a patient has elevated triglycerides and a low HDL-C, this indicates a high likelihood of insulin resistance. The higher the TG:HDL-c ratio, the greater the likelihood that insulin resistance is present. In these cases, consider using a non-HDL-C, apoB or LDLparticle number. In many studies, these appear to be superior predictors of risk when compared to LDL.^19-24 Prescribing a statin would be the recommended initial treatment when pharmacologic therapy is chosen. This is based on many studies showing reductions in cardiovascular risk with use of these agents.²⁵ In both of our practices, we strive for the triple goal of LDL-C, non-HDL-C and LDL-P at their respective targets when discordance is suspected or the patient is considered high risk. That way, any discordance is captured and that patient gets more appropriate treatment.

It is important to emphasize the benefits of regular exercise, which has been shown to improve triglyceride and HDL cholesterol levels, along with a host of benefits on other parameters of wellbeing and health. The American Heart Association recommendation is for patients to strive for 150 minutes (two and half hours) a week of moderate activity—divided in any way that is attainable by patients.

In addition, don’t forget to review the patient’s diet and see where beneficial changes can be made in regards to less carbohydrates and adding lean sources of proteins and good fats. The use of a dietitian can be a useful resource when taking into consideration cultural and ethnic considerations in this arena.

Finally, remember to review all cardiovascular risk factors and modify them if possible. Encourage smoking cessation, treat hypertension to goal and remind patients that even small changes in dietary or lifestyle habits can have beneficial effects on their cholesterol.

Disclosure statement: Dr. Selagamsetty has no disclosures to report. Dr. Uusinarkaus has served on the speakers’ bureaus for Merck & Co., GlaxoSmithKline, Forest Laboratories, AstraZeneca, Kowa Pharmaceutals America, Amarin Corp., and Vivus Pharmaceuticals. Dr. Uusinarkaus has served on the advisory board for Aegerion Pharmaceuticals.