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To screen for dyslipidemia in foreign-born persons, total cholesterol alone is not optimal.
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High low-density lipoprotein cholesterol, low high-density lipoprotein cholesterol, and high triglycerides are most prevalent in foreign-born persons.
Background
With an increasing foreign-born population in the United States, cardiovascular risk reduction through effective lipid treatment strategy is precluded by limited lipid profile information.
Objective
This study compares the patterns of lipid abnormalities of foreign-born and US-born patients treated by a single medical group.
Methods
We conducted a medical record review of 53,361 US-born and 6430 foreign-born patients in 2010.
Results
Compared with US-born, a higher proportion of foreign-born patients are younger than 40 years (26% vs 14%), receive Medicaid (24% vs 8%), and are less likely to be obese (26% vs 43%). More foreign-born patients have diabetes (25% vs 22%), are poor (4.7% vs 3.6%), and not on lipid-lowering drugs (63% vs 56%). Place of birth is not associated with total cholesterol levels. Adjusted for social and demographic characteristics, however, foreign-born are more likely than US-born to have elevated low-density lipoprotein cholesterol (adjusted difference, 2.1; 95% CI, 0.6–3.7), depressed high-density lipoprotein cholesterol (adjusted difference, 6.1; 95% CI, 4.4–7.8), and elevated triglycerides (adjusted difference, 2.4; 95% CI, 0.8–4.1). Foreign-born patients, on lipid-lowering medications, are more likely to still have elevated levels of low-density lipoprotein cholesterol (adjusted difference, 3.5; 95% CI, 1.4–5.6).
Conclusion
Despite having a similar distribution of total cholesterol as their US-born counterparts, the other lipid fractions among foreign-born patients are more likely to be pathologic. Therefore, dyslipidemia screening tests need to include the lipid subfractions. The higher prevalence of dyslipidemias, both among foreign-born patients with and without lipid-lowering medications, challenges medical groups to intensify effective lipid treatment strategies.
The Foreign-Born Population in the United States: 2010. American Community Survey Reports. U.S. Census Bureau. May 2012. Available at: http://www.census.gov/prod/2012pubs/acs-19.pdf. Accessed June 11, 2013.
Although foreign-born residents are usually healthy when they arrive, their health advantages decline over time, partly because of the deteriorating socioeconomic status that tends to come with longer US residency.
The Foreign-Born Population in the United States: 2010. American Community Survey Reports. U.S. Census Bureau. May 2012. Available at: http://www.census.gov/prod/2012pubs/acs-19.pdf. Accessed June 11, 2013.
The length of US residency contributes to the development of unfavorable risk factors in foreign-born persons. For example, foreign-born tend to have higher body mass index (BMI; calculated as weight divided by height squared; kg/m2) and higher atherosclerotic risk (ie, 2% increase in intima media thickness) if they have lived in the United States for >10 years.
The role of hyperlipidemia in the pathogenesis of atherosclerosis underscores the need for intensive lipid management, especially in a high-risk population such as the foreign-born, to reduce cardiovascular mortality. However, complete lipid profile information among foreign-born persons is lacking despite higher cardiovascular risk. Compared with race, country of origin is infrequently studied in cardiovascular disease research. Perhaps because collection of these data is not federally mandated or minority status is often used as exclusion criteria.
Because the foreign-born are a fast-growing, vulnerable population that acquires unfavorable cardiovascular risk and socioeconomic profiles over time, it is crucial to identify their lipid abnormalities. We wanted to define the prevalence of lipid abnormalities in the foreign-born and compare them with lipid abnormalities of our US-born patients. Characterizing the burden of dyslipidemia in foreign-born persons creates an opportunity to target efforts to improve and intensify the implementation of culturally sensitive cardiovascular risk-reduction programs.
Methods
Patient selection
This is a single-site study with data collected retrospectively from January to December 2010. The HealthPartners Institutional Review Board approved the study. We analyzed the data obtained from electronic health record (EHR) of patients who were treated at one of the HealthPartners Medical Group clinics. We use the term patients instead of subjects because all persons whose data are included in the analysis were treated by a physician. We included patients who were at least 20 years old, had a complete lipid panel (low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], total cholesterol, and triglycerides) collected as an outpatient and, with the exception of Hmong- and Spanish-speaking persons, country of origin information (Fig. 1). We assumed that Hmong-speaking patients came from Southeast Asia and that Spanish-speaking patients came from Latin America.
Figure 1Flow chart of foreign- and US-born patient selection. US, United States.
Characterizing country of birth and grouping of countries
We divided the patients into 2 main groups: US-born and foreign-born. We defined foreign-born as people who were born outside the United States but residing in the United States regardless of their legal immigration status. With the exception of Spanish- and Hmong-speaking patients, we included only patients with country of origin documented in the EHR. Following the United Nations Millennium Developmental Goals geographic divisions, we grouped the 24 countries represented by our patients into the following categories: Africa (Cameroon, Eritrea, Ethiopia, Kenya, Liberia, Nigeria, Somalia, South Africa, and Egypt), Eastern Asia (China and Korea), Southern Asia (India, Nepal, and Pakistan), Southeastern Asia (Cambodia, Laos, Philippines, Thailand, and Vietnam), Latin America (Mexico and El Salvador), Europe (Russia, Bosnia, and Herzegovina), and Canada. The list of countries in this analysis is limited by the origins of the study population.
Lipid classification and classification of covariates
We classified the lipid components as abnormal if the total cholesterol was ≥200 mg/dL, LDL-C was ≥130 mg/dL, HDL-C was ≤39 mg/dL (men) or ≤49 mg/dL (women), or triglycerides were ≥150 mg/dL. We classified patients as diabetic if they were taking diabetic medications or had a diagnosis of diabetes mellitus (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes, 250.00–250.93). We classified patients as hypertensive if their systolic blood pressure was ≥130 mm Hg or the diastolic blood pressure was ≥85 mm Hg or they were taking medication for hypertension. Patients were classified as having cardiovascular disease (CVD) if they had one or more of the following ICD-9-CM codes: 410 to 414, 425, and 428 to 438. We used insurance claims, lists of prescribed medications, and medication reconciliation lists to determine the medications that the patients were taking. We collapsed age into 3 groups (≥20–39, 40–64, and ≥65 years). We classified the patients' race and ethnicity as white, black, Asian, Hispanic, mixed, or other race. We used the percentage of households below the poverty level in the patient's geographic code of residence to define their economic status. Poverty thresholds vary according to size of the family and ages of the members to determine poverty status.
Statistical analyses
We used frequency distributions, percentages, and means to describe the differences in sociodemographic characteristics, CVD risk factors, and lipid abnormalities between foreign-born and US-born patients. We tested the significance of the differences with χ2 and t tests. We used general linear models to adjust for differences in age, sex, race, smoking, type of health care insurance, BMI, poverty, use of lipid-lowering drugs, CVD, hypertension, and diabetes. We were able to use general linear models because prevalence rates are at the center of the distribution space. In addition, we obtained adjusted abnormalities stratified by the use of lipid-lowering drugs. We used similar modeling to describe the prevalence of lipid abnormalities within the various foreign-born subgroups. We considered associations with a P value < .05 to be statistically significant.
Results
Population characteristics
This study includes 6430 foreign-born and 53,361 US-born patients. Foreign-born patients tend to be younger, men, Asian or Black, nonsmokers, and have Medicaid insurance, whereas US-born patients tend to be older, women, white, smokers, and have private health insurance (Table 1). More US-born patients (43%) than foreign-born patients (26%) have a BMI ≥ 30. Diabetes mellitus is more prevalent among foreign-born patients, but US-born patients are more likely to have hypertension or a diagnosis of CVD. Foreign-born patients are more likely to have a household income below the poverty level. The demographic profiles of patients who were excluded from the analysis because country of origin data were missing resemble those of the US-born patients. Without adjustment for other factors, the mean total cholesterol values of the foreign-born and US-born patients are nearly identical (Table 1). The mean LDL-C value is modestly higher for foreign-born patients than for US-born patients. The mean HDL-C is lower for foreign-born patients as is the mean triglyceride level.
Table 1Clinical characteristics of foreign-born and US-born patients
Variable
Foreign-born (n = 6430), n (%)
US-born (n = 53,361)
P value
Age group, n (%)
<.001
20–39 y
1651 (26)
7382 (14)
40–64 y
3707 (58)
34,111 (64)
≥65 y
1072 (16)
11868 (22)
Sex, n (%)
<.001
Female
3404 (53)
29,621 (56)
Male
3026 (47)
23,740 (44)
Race, n (%)
<.001
White
898 (14)
47,853 (90)
Black
1824 (28)
3494 (7)
Asian
2536 (39)
276 (<1)
Hispanic
554 (9)
607 (1)
Mixed
18 (<1)
121 (<1)
Other
459 (7)
408 (<1)
Unknown
141 (2)
602 (1)
Marital status, n (%)
<.001
Single
1000 (16)
10,072 (19)
Married
3268 (51)
27,758 (52)
Divorced
447 (7)
5448 (10)
Unknown
1715 (26)
10,083 (19)
Insurance, n (%)
<.001
Medicare
588 (9)
11,416 (21)
Medicaid
1569 (24)
4007 (8)
Dual M-M
384 (6)
335 (<1)
Private
3864 (60)
37,378 (70)
Unknown
25 (<1)
225 (<1)
Body mass index, n (%)
<.001
0–18.4
123 (2)
1187 (2)
18.5–24.9
1862 (29)
10,367 (20)
25–29.9
2307 (36)
16,638 (31)
≥30
1644 (26)
23,047 (43)
Unknown
494 (7)
2122 (4)
With lipid medication, n (%)
2369 (37%)
23,435 (44%)
<.001
Mean Lipid values, mean ± SD
Total cholesterol, mg/dL
189.6 ± 37.9
189.2 ± 38.4
.41
LDL-C, mg/dL
113.1 ± 33.6
109.8 ± 33.6
<.001
HDL-C, mg/dL
49.5 ± 13.5
51.8 ± 15.3
<.001
Triglycerides, mg/dL
135.6 ± 74.5
138.8 ± 74.3
.001
Smoking status, n (%)
479 (7)
8485 (16%)
<.001
Hypertension, n (%)
3,092 (48)
32,918 (62%)
<.001
Diabetes mellitus, n (%)
1605 (25)
11,563 (22%)
<.001
Cardiovascular disease, n (%)
696 (11)
9143 (17%)
<.001
Households below poverty, %
4.7
3.6
<.001
Patients aged ≥25 years without a high school education, %
8.8
7.7
<.001
HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; US, United States.
Crude and adjusted prevalence rates of lipid abnormalities for foreign-born patients relative to US-born patients
When all patients are considered together, the crude and adjusted prevalence rate of elevated total cholesterol is nearly identical for foreign- and US-born patients. Among patients not taking lipid-lowering drugs the crude prevalence rate is higher for US-born patients. Conversely, the crude prevalence rate is higher for foreign-born among the patients who are taking lipid-lowering drugs. The adjusted prevalence difference of elevated total cholesterol is no different for foreign-born and US-born patients whether or not they are taking lipid-lowering drugs.
Overall, the adjusted prevalence difference of an elevated LDL-C is higher for foreign-born than for US-born patients (2.1; 95% CI, 0.6–3.7). Foreign-born patients who are not taking lipid-lowering drugs had a higher adjusted prevalence rate of elevated LDL-C than US-born patients (2.3; 95% CI, 0.1–4.4). The adjusted prevalence rate of an elevated LDL-C among foreign-born patients who are taking lipid-lowering drugs is higher than for US-born patients.
As with the crude prevalence rate, the adjusted prevalence rate of an abnormally low HDL-C level is greater for the foreign-born patients than for the US-born patients (6.1; 95% CI, 4.4–7.8). This is also true for foreign-born patients who are not on lipid-lowering drugs. Among patients taking lipid-lowering drugs, however, the adjusted prevalence difference is not statistically significant between foreign-born and US-born patients.
The crude prevalence rate of elevated triglyceride levels is higher for US-born patients than for foreign-born patients. However, the adjusted prevalence of having elevated triglycerides is higher for foreign-born than for US-born patients (2.4; 95% CI, 0.8–4.1). Among patients not taking lipid-lowering drugs, foreign-born patients were more likely to have elevated triglycerides. The association with place of birth is not significant for patients taking lipid-lowering drugs (Table 2).
Table 2Prevalence rate and adjusted analysis of lipid abnormalities in foreign- and US-born patients with and without lipid drugs
Crude and adjusted prevalence of lipid abnormalities in US-born and foreign-born subgroups
Compared with US-born patients, 38% of whom had elevated total cholesterol while patients from Southeastern Asia (41%), Eastern Asia (40%), Europe/Canada (40%), and Latin America (39%) had a higher crude prevalence of elevated total cholesterol. Patients from Southern Asia have the lowest adjusted prevalence of elevated total cholesterol among foreign-born subgroups, and the difference is statistically significant compared with patients from Southeastern Asia and Europe/Canada and with US-born patients (Table 3). Patients from Africa have similar adjusted prevalence of elevated total cholesterol with patients from Latin America and the US-born. Likewise, the adjusted prevalence of elevated total cholesterol of patients from Latin America is not different from the other foreign-born subgroups.
Table 3Prevalence rate and adjusted analysis of lipid abnormalities in foreign- and US-born patients
Statistically significant (P < .05) subgroup-adjusted comparisons were as follows: elevated total cholesterol (Africa and Southeastern Asia, Africa and Europe/Canada, Eastern Asia and Southeastern Asia, Southern Asia and Southeastern Asia, Southern Asia and Europe/Canada, Southern Asia and United States, Southeastern Asia and United States); elevated LDL-C (Africa and Southern Asia, Europe/Canada, Eastern Asia and Southeastern Asia, Eastern Asia and Europe/Canada, Southern Asia and Southeastern Asia, Southern Asia and Europe/Canada, Southern Asia and United States, Europe/Canada and United States); low HDL-C (Africa and Southern Asia, Europe/Canada, Africa and United States, Eastern Asia and Southern Asia, Southern Asia and Southeastern Asia, Southern Asia and Latin America, Southern Asia and Europe/Canada, Southern Asia and United States, Southeastern Asia and Europe/Canada, Southeastern Asia and United States); elevated triglycerides (Africa and Southern Asia, Africa and Southeastern Asia, Eastern Asia and Europe/Canada, Eastern Asia and United States, Southern Asia and Europe/Canada, Southern Asia and United States, Southeastern Asia and Europe/Canada, Southeastern Asia and United States).
Latin America included Mexico and El Salvador and Spanish language.
(n = 305)
Europe/Canada
Europe/Canada included Russia, Bosnia, Herzegovina, and Canada.
(n = 243)
US reference
Elevated total cholesterol
Crude prevalence
32
40
29
41
39
40
38
Adjusted prevalence
35
37
31
42
39
42
38
Elevated LDL cholesterol
Crude prevalence
29
27
22
30
29
33
27
Adjusted prevalence
27
24
22
30
28
35
27
Low HDL cholesterol
Crude prevalence
42
31
49
39
47
33
36
Adjusted prevalence
45
40
54
41
40
33
35
Elevated triglycerides
Crude prevalence
20
35
39
42
42
29
34
Adjusted prevalence
35
39
42
41
36
29
33
HDL, high-density lipoprotein; LDL, low-density lipoprotein; US, United States.
∗ Lipid abnormalities were as follows: elevated total cholesterol (≥200 mg/dL); elevated LDL cholesterol (≥130 mg/dL); low HDL cholesterol (≤39 mg/dL for men, ≤49 mg/dL for women); and elevated triglycerides (≥150 mg/dL).
† Statistically significant (P < .05) subgroup-adjusted comparisons were as follows: elevated total cholesterol (Africa and Southeastern Asia, Africa and Europe/Canada, Eastern Asia and Southeastern Asia, Southern Asia and Southeastern Asia, Southern Asia and Europe/Canada, Southern Asia and United States, Southeastern Asia and United States); elevated LDL-C (Africa and Southern Asia, Europe/Canada, Eastern Asia and Southeastern Asia, Eastern Asia and Europe/Canada, Southern Asia and Southeastern Asia, Southern Asia and Europe/Canada, Southern Asia and United States, Europe/Canada and United States); low HDL-C (Africa and Southern Asia, Europe/Canada, Africa and United States, Eastern Asia and Southern Asia, Southern Asia and Southeastern Asia, Southern Asia and Latin America, Southern Asia and Europe/Canada, Southern Asia and United States, Southeastern Asia and Europe/Canada, Southeastern Asia and United States); elevated triglycerides (Africa and Southern Asia, Africa and Southeastern Asia, Eastern Asia and Europe/Canada, Eastern Asia and United States, Southern Asia and Europe/Canada, Southern Asia and United States, Southeastern Asia and Europe/Canada, Southeastern Asia and United States).
‡ Africa included Cameroon, Eritrea, Ethiopia, Kenya, Liberia, Nigeria, Somalia, South Africa, and Egypt.
§ Eastern Asia included China and Korea.
¶ Southern Asia included India, Pakistan, and Nepal.
|| Southeastern Asia included Cambodia, Laos, Philippines, Thailand, and Vietnam and Hmong language.
# Latin America included Mexico and El Salvador and Spanish language.
∗∗ Europe/Canada included Russia, Bosnia, Herzegovina, and Canada.
Compared with US-born patients, the crude prevalence of elevated LDL-C is higher among patients from Europe/Canada (33%), Southeastern Asia (30%), Latin America (29%), and Africa (29%). In addition to having the lowest adjusted prevalence of elevated total cholesterol, patients from Southern Asia also have the lowest adjusted prevalence of elevated LDL-C. The adjusted prevalence of elevated LDL-C is highest among patients from Europe/Canada, and the difference is statistically significant compared with patients from Africa, Eastern Asia, and Southern Asia and with the US-born. However, the adjusted prevalence difference of elevated LDL-C between patients from Latin America and patients from Europe/Canada is not significant. For patients from Africa, the adjusted prevalence of elevated LDL-C is only significant compared with patients from Southern Asia and Europe/Canada.
Compared with the prevalence of low HDL-C among US-born patients (36%), the crude prevalence of low HDL-C is higher in patients from Southern Asia (49%), Latin America (47%), Africa (42%), and Southeastern Asia (39%). Patients from Southern Asia have the highest adjusted prevalence of low HDL-C (54%); the adjusted difference is statistically significant compared with all other foreign-born subgroups and with the US-born. However, patients from Latin America have a prevalence rate of low HDL-C similar to all the foreign-born subgroups except for patients from Southern Asia. The prevalence of low HDL-C among patients from Europe and Canada is not statistically significant compared with US-born patients.
The crude prevalence of elevated triglycerides is higher among patients from all Asian foreign-born subgroups and Latin America compared with US-born patients. Patients from Southern Asia have the highest adjusted prevalence of elevated triglycerides, but the adjusted prevalence difference is significant only compared among patients from Africa and Europe/Canada and with US-born patients. The adjusted prevalence difference of elevated triglycerides among patients from Africa is not statistically significant compared with patients from Latin America and Europe/Canada and with US-born patients. However, the prevalence of elevated triglycerides among patients from Latin America is not statistically different from all foreign-born subgroups, including US-born patients.
Discussion
Although an elevated total cholesterol level is not more prevalent among the foreign-born than the US-born in our patient sample, elevated LDL-C levels, low HDL-C levels, and elevated triglyceride levels tend to be. An exception occurs only among patients from Southeastern Asia and Latin America who have a slightly different lipid pattern. These patients also tend to have levels of total cholesterol, LDL-C, and triglyceride levels that are higher than the levels of their US-born counterparts, including lower HDL-C levels. These findings suggest that screening for dyslipidemia among foreign-born patients solely with an assessment of the total cholesterol level will miss a considerable proportion of patients who have a dyslipidemia. Because elevated LDL-C levels persist even with drug treatment suggests that more effective, culturally sensitive treatment programs are needed. For example, simple meal planning and a physical activity program while considering personal preferences, cultural practices, and their socioeconomic status may prove to be successful. Although foreign-born patients may be treated less aggressively than their US-born counterparts, adherence among the foreign-born is made more challenging by disparities and low educational attainment.
Although it may seem easier for migrants from Canada and Europe to adapt to Western culture and live a healthier lifestyle than migrants from developing countries, we still found that an elevated LDL-C is more prevalent in this group than in the US-born population despite controlling for CVD and socioeconomic variables. Many foreign-born patients are poor and tend to rely on public insurance for health coverage. Studies have also reported that less-educated immigrants often lose insurance coverage over time, which lessens the opportunity to access preventive services.
This observation is evident in our study because many foreign-born patients are given a diagnosis of hyperlipidemia less often than US-born patients. Likewise, foreign-born patients are also less treated with lipid-lowering drugs. Regardless of race, an elevated LDL-C remains prevalent in the foreign-born population whether not they take lipid-lowering drugs.
The relationship between low HDL-C and risk of coronary artery disease and the cardiometabolic syndrome (CMS) is relevant in understanding excess coronary artery disease risk in the foreign-born, especially if they migrated from countries with a high prevalence of CMS. Such is the case of foreign-born patients from Southern Asia, Southeastern Asia, and Latin America who had a higher prevalence of CMS in our study than other foreign-born subgroups (30%, 33%, and 37%, respectively; table not included). Efforts to improve HDL-C and triglyceride levels among foreign-born patients through weight control and exercise can be impeded by cultural and religious beliefs; being thin in some cultures is a sign of illness and poverty, whereas being overweight or obese is viewed as an indicator of good health.
Compared with the US-born, the high prevalence of hypertriglyceridemia in foreign-born patients is multifactorial in cause. It can be attributed to a carbohydrate-rich diet, food insecurity because of poverty, or susceptibility to carbohydrate-induced hypertriglyceridemia such as CMS.
Excess intake of carbohydrates predisposes to obesity, especially if the patient has lived in the United States >10 years. When we look at the lipid abnormalities of obese foreign-born patients, they consist of high triglycerides, an elevated LDL-C, and low HDL-C, the features of mixed dyslipidemia and CMS.
On the basis of published literature, the effect of isolated hypertriglyceridemia on CVD was not as clear as it was in low HDL-C.
However, the Copenhagen Male Study found that the joint effect of low HDL-C and hypertriglyceridemia predicts ischemic heart disease, similar to isolated elevation of LDL-C.
Relation of high TG-low HDL cholesterol and LDL cholesterol to the incidence of ischemic heart disease. An 8-year follow-up in the Copenhagen Male Study.
The significance of metabolic dyslipidemia (low HDL-C and high triglycerides) and its association with insulin resistance predicts CVD, which adds another layer of risk stratification when these phenotypes coexist with an elevated LDL-C.
Our observation of a high prevalence of high total cholesterol among foreign-born subgroups from developed countries and Latin America is consistent with the World Health Organization (WHO) global prevalence statistics on elevated cholesterol.
However, the prevalence of high total cholesterol among subgroups of foreign-born patients (Eastern Asia, 40%; Southeastern Asia, 41%) is in contrast to findings in the WHO report. This observation might be attributed to the influence of Westernization, because the prevalence of high total cholesterol is usually associated with income level in the country of residence.
In a nation-wide Mexican survey, the most prevalent lipid abnormality was low HDL-C, followed by hypertriglyceridemia which is consistent with the lipid abnormalities of our patients from Latin America.
However, when we analyzed the adjusted prevalence of the components of lipid panel of patients from Latin America, they were not different compared with patients from Africa, Eastern Asia, Southeastern Asia, and Europe/Canada and the US-born patients except for patients from Southern Asia (high adjusted prevalence of low HDL-C). Because the prevalence of lipid abnormalities among patients from Latin America is not different from most of the foreign-born subgroups suggests that other variables such as diet, physical activity, or length of residency may have to be studied in future research. We were unable to include these variables in our analysis. Likewise, patients from Southern Asia tend to have lipid abnormalities that are cardiometabolic as well. They are characterized by high prevalence of low HDL-C and high triglyceride levels but extremely low prevalence of high LDL-C. In the INTERHEART study, a high prevalence of low LDL-C was observed among Chinese, Japanese, and Southern Asians.
By contrast, the adjusted prevalence of each component of the lipid panel among patients from Asia is not entirely homogeneous. Patients from Southeastern Asia have lipid abnormalities characterized by high prevalence of both high total cholesterol and high LDL-C compared with patients from Eastern and Southern Asia. The crude prevalence of low HDL-C and high triglycerides was higher in patients from Southern Asia than in patients from Eastern and Southeastern Asia. These findings suggest that variability of lipid abnormalities exist when country of birth is used as an exposure variable. Difference in risk profile and CVD mortality among Asians had been found in prior studies. For instance, persons from South Asia, which include India and Pakistan, tend to present with high cause-specific death rates from ischemic heart disease because of high incidence of premature CVD compared with people from China.
The prevalence of lipid abnormalities among patients from Africa differs from foreign-born subgroups from Asia and Europe/Canada and from the US-born patients. However, the prevalence is not different compared with patients from Latin America. Our findings of prevalent high total cholesterol and high LDL-C among patients from Europe/Canada is consistent with Swedish patients in the PRIMULA study.
There is disagreement about which components ought to be included in a screening lipid profile. The National Cholesterol Education Program recommends measuring LDL-C, HDL-C, total cholesterol, and triglycerides, whereas the US Preventive Services Task Force recommends measuring only total cholesterol and HDL-C.
National Institutes of Health. Third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). Executive summary. NIH Publication No. 01–3670. Available at: http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3sum. Accessed June 11, 2013.
When the Center for Disease Control and Prevention examines the immigrants and refugees for cardiac risk, only total cholesterol and HDL-C are tested. In cross-country comparisons and surveys of global burden of CVD, the WHO only reports total cholesterol.
On the basis of the results of our study, testing of total cholesterol alone will miss significant proportions of foreign-born patients with dyslipidemia. Measuring all components of the fasting lipid profile is ideal when screening or during follow-up in the foreign-born population. However, this strategy can be prohibitively expensive and may preclude many foreign-born patients from getting optimal comprehensive lipid management.
In our study, 4 times as many foreign-born patients as US-born patients rely on Medicaid, an insurance program that may require cost-sharing.
The undocumented foreign-born population may have affected the composition of our study patients compared with the national level, if the foreign-born population is identified only by country of birth. In the state of Minnesota, the composition of foreign-born population by country of birth mirrors the composition of our study patients. This is predominated by Asians (35.8%), followed by Latin Americans (28.1%) or Africans (20.6%).
By contrast, 52.6% of immigrants in the United States are from Latin America, followed by Asia (28.6), Europe (12.1%), and Africa (4.1%). Because there is a paucity of cardiovascular research that uses country of birth as an exposure variable, we recommend caution when comparing and interpreting our results.
Study strengths and limitations
The sample size of our foreign-born population, including subgroups, allowed comparative description of lipid profiles with those of our US-born patients. The clinical and demographic information obtained from the EHR allowed comparison of different foreign-born subgroups, which is also important in understanding CVD risk similarities and differences. The adjusted analysis, using country of birth as an exposure variable, has also provided information that is relevant not only in formulating treatment strategies for managing dyslipidemia in foreign-born patients but also in laying the groundwork for future research into the effect of country of birth on CVD risk. To avoid potential biases, we selected only patients with a complete lipid profile that contained all 4 components and was processed in a laboratory that uses a similar method and range of normal values to minimize discordance. Most important, this is the first study performed in a medical group to use country of birth as an exposure variable to describe the lipid profile patterns of foreign-born residents in the United States. Because country of birth is self-reported information, our observation should be taken with a caveat. Because number of years since arrival is not available, and lipid testing is not a federally required part of the immigration process, the lipid abnormalities we observed may have been preexisting or may have developed in association with residing in the United Sates. Patients who were excluded from the analysis were mostly English-speaking, white, and obese and have similar comorbidities as the US-born patients. This suggests that, in fact, most of them were born in the United States.
Conclusion
Our findings in the foreign-born population underscore the importance of intensifying culturally sensitive treatment guidelines. The presence of an elevated LDL-C with low HDL-C or high triglycerides in foreign-born patients calls for early intervention to reduce cardiovascular disease risk and prevent premature deaths from CVD. Prescribing lipid-lowering drugs, dietary changes, and increased physical activity remain the cornerstones of CVD prevention. Testing for total cholesterol or HDL-C or both during screening or follow-up is not optimal and will not capture a significant proportion of dyslipidemia among foreign-born patients. To be successful, intervention programs should account for differences in religious practices, cultural beliefs, and barriers to adherence. However, these treatment strategies will remain challenging if barriers to improve access and to reduce disparities are not addressed as well. In that case, lower utilization of health care services will continue as we observed, with fewer foreign-born patients getting screening, diagnosis, and treatment. Finally, country of birth is an important exposure variable, and we recommend considering it in cardiac risk stratification, because the size of the foreign-born population in the United States, which has elevated lifelong CVD risk, is increasing.
Financial disclosure
This research was supported by The HealthPartners Research Foundation and The Heart Disease and Stroke Prevention Unit at the Minnesota Department of Health from a Capacity Building-Cooperative Agreement grant from the Centers for Disease Control and Prevention, and from the National Institutes of Health training grant T32 HL69764. The funder had no role in the design of the study and the analysis and interpretation of data. The authors report no financial disclosure or conflict of interest.
References
The Foreign-Born Population in the United States: 2010. American Community Survey Reports. U.S. Census Bureau. May 2012. Available at: http://www.census.gov/prod/2012pubs/acs-19.pdf. Accessed June 11, 2013.
Relation of high TG-low HDL cholesterol and LDL cholesterol to the incidence of ischemic heart disease. An 8-year follow-up in the Copenhagen Male Study.
National Institutes of Health. Third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). Executive summary. NIH Publication No. 01–3670. Available at: http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3sum. Accessed June 11, 2013.
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