Trends in ATP-III-Defined High Blood Cholesterol Prevalence, Awareness, Treatment and Control Among U.S. Adults

Trends in ATP-III-Defined High Blood Cholesterol Prevalence, Awareness, Treatment and Control Among U.S. Adults AMANDA D. HYRE, MPH, PAUL MUNTNER, PHD, ANDY MENKE, MPH, PAOLO RAGGI, MD, AND JIANG HE, MD, PHD

PURPOSE: We sought to determine trends in the prevalence, awareness, treatment and control of high low-density lipoprotein (LDL) cholesterol among U.S. adults. METHODS: Data from 6497 participants of the Third National Health and Nutrition Examination Survey (NHANES) conducted in 19881994 and 5626 participants of NHANES 19992004 were compared. High LDL cholesterol was defined using risk-specific cut-points from the National Cholesterol Education Program’s Adult Treatment Panel III guidelines. RESULTS: The age-standardized percentage of U.S. adults with high LDL cholesterol was 26.6% in 19881994 and 25.3% in 19992004 (P Z 0.28). Between 19881994 and 19992004, awareness increased from 39.2% to 63.0%, and use of pharmacologic lipid-lowering treatment increased from 11.7% to 40.8% (each p ! 0.001). LDL cholesterol control increased from 4.0% to 25.1% among those with high LDL cholesterol (p ! 0.001). In 19992004, rates of LDL cholesterol control were lower among adults ages 2049 years compared with those age 65 years or older (13.9% vs. 30.3%; p ! 0.001); non-Hispanic blacks and Mexican-Americans compared with non-Hispanic whites (17.2% and 16.5% vs. 26.9%, respectively; p Z 0.05 and p Z 0.008); and males compared with females (22.6% vs. 28.0%; p Z 0.01). CONCLUSIONS: Continued efforts are needed to lower the burden of high LDL cholesterol and increase LDL cholesterol control, especially among populations with low control rates. Ann Epidemiol 2007;17:548–555. Ó 2007 Elsevier Inc. All rights reserved. KEY WORDS:

Lipoproteins, LDL Cholesterol, Guidelines, NHANES.

INTRODUCTION A major modifiable risk factor in the development of atherosclerosis and subsequent coronary heart disease (CHD) is increased levels of low-density lipoprotein (LDL) cholesterol (1). Statin therapy has been shown to lower LDL cholesterol by 30% to 40% and reduce CHD incidence by 23% to 31% (2, 3). The National Cholesterol Education Program’s third Adult Treatment Panel (ATP-III), along with an update including results from five major lipid-lowering clinical trials, provide guidelines for the diagnosis and treatment of high blood cholesterol (3, 4). Previous analyses have identified trends in higher awareness, treatment, and control of total cholesterol. However, the ATP-III guidelines recommend LDL cholesterol as the primary target of clinical lipid management. Therefore, it may be more relevant to characterize trends in high LDL cholesterol for U.S. adults.

From the Department of Epidemiology (A.D.H., P.M., A.M., J.H.), Tulane University School of Public Health and Tropical Medicine and Department of Medicine (P.M., J.H.), Tulane University School of Medicine, New Orleans, LA; and Department of Medicine and Radiology (P.R.), Emory University School of Medicine, Atlanta, GA. Address correspondence: Amanda Hyre, Department of Epidemiology, Tulane University SPHTM, 1440 Canal Street, SL-18, New Orleans, LA 70112. Tel.: 504-988-3855; fax 504-988-7448. E-mail: [email protected]. Received November 4, 2006; accepted January 4, 2007. Ó 2007 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010

The primary aim of the present analysis was to determine trends in the percentage of U.S. adults ages 20 years and older with high LDL cholesterol in 19881994 and 19992004 using serial National Health and Nutrition Examination Surveys (NHANES) and cut-points derived from the ATP-III guidelines. Additionally, trends in high LDL cholesterol awareness, treatment and control were calculated over this same time period.

METHODS Study Population Data from the current study were derived from NHANES III for 1988 through 1994 and NHANES 19992004. These surveys, conducted by the National Center for Health Statistics of the Centers for Disease Control and Prevention, are nationally representative samples of the noninstitutionalized civilian U.S. population identified through a stratified, multistage probability sampling design. In each survey, participants were asked to complete in-home interviews followed by a visit to a mobile examination center for the administration of additional questionnaires, a medical examination, and collection of a blood sample. In NHANES III and NHANES 19992004, 7167 and 6021 participants, respectively, 20 years and older completed the in-home interview and had a blood sample 1047-2797/07/$–see front matter doi:10.1016/j.annepidem.2007.01.032

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Selected Abbreviations and Acronyms CHD Z coronary heart disease LDL Z low-density lipoprotein ATP-III Z Adult Treatment Panel III NHANES Z National Health and Nutrition Examination Survey HDL Z high-density lipoprotein MI Z myocardial infarction

collected after a 9-h or longer fast during a morning medical examination. After exclusion of individuals with a triglyceride level O400 mg/dL, and those missing lipoprotein and covariable information, data from 6497 adults from NHANES III and 5626 adults from NHANES 19992004 were available for analysis. ATP-III Guidelines ATP-III Treatment Recommendations. The ATP-III guidelines classify patients into CHD risk categories based on the presence of CHD, risk equivalents, and risk factors. ATP-III guidelines define high LDL cholesterol warranting therapeutic lifestyle changes and consideration of pharmacologic lipid-lowering therapy as LDL cholesterol >100 mg/dL for patients with CHD and/or CHD risk equivalent(s). For the remaining patients without CHD or a risk equivalent, high LDL cholesterol is defined as LDL cholesterol >130 mg/dL for patients with two or more CHD risk factors and a 10-year CHD risk of 1020%, LDL cholesterol >160 mg/dL for patients with two or more CHD risk factors and a 10-year CHD risk !10%, and LDL cholesterol >190 mg/dL for patients with 0-1 CHD risk factors. Major CHD Risk Factors. Major CHD risk factors in the ATP-III guidelines include cigarette smoking, hypertension, low high-density lipoprotein (HDL) cholesterol (!40 mg/dL), family history of premature CHD (i.e., CHD in a first-degree male relative !55 years of age or in a first degree female relative !65 years of age), and older age (men >45 years; women >55 years). HDL cholesterol >60 mg/dL is considered protective and offsets the presence of one other risk factor. CHD and CHD Risk Equivalents. The ATP-III guidelines define CHD as a history of a myocardial infarction (MI), angina, and/or coronary procedures. CHD risk equivalents include stroke, other clinical atherosclerotic diseases (e.g., peripheral arterial disease), diabetes mellitus, and multiple CHD risk factors in the presence of a 10-year CHD risk O20% as calculated by the Framingham risk equation (5). Data Collection Questionnaires were used to assess demographics, cigarette smoking, family history of CHD, antihypertensive medication use, history of CHD, stroke, angina, and diabetes mellitus, a previous diagnosis of high blood cholesterol, and the

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use of lipid-lowering drugs as the result of a previous diagnosis of high cholesterol. Participants were classified as having hypertension if, based on the average of three blood pressure measurements at the medical examination, they had a systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg and/or they reported currently using antihypertensive medication. Documentation of a family history of CHD in NHANES was limited to a participantreported history of MI or angina before age 50 among firstdegree relatives. The presence of CHD was defined as a self-reported history of MI and/or angina pectoris. Angina was assessed through the Rose questionnaire in NHANES III and in participants >40 years of age in NHANES 20012004, and as an affirmative response to the question, ‘‘Has a doctor or other health professional ever told you that you had angina, also called angina pectoris?’’ for the remaining participants (6). CHD risk equivalents in the current analysis included a history of stroke (self-reported), diabetes mellitus (self-reported and/or a fasting plasma glucose >126 mg/dL at the NHANES visit) and, for individuals with two or more major CHD risk factors, a 10-year CHD risk O20%. Blood samples from each survey were stored at 20 C and shipped to the Lipoprotein Analytical Laboratory at Johns Hopkins University in Baltimore, Maryland, for lipid analyses and to the University of Missouri at Columbia for glucose analyses (7, 8). Total- and HDL-cholesterol in addition to triglycerides were measured using the Hitachi 704 Analyzer and reagents purchased from Roche/Boehringer Mannheim Diagnostics (Indianapolis), IN. LDL cholesterol was calculated using the Friedewald equation: LDL cholesterol ½mg=dLZtotal cholesterol ½mg=dL  HDL cholesterol ½mg=dL  triglycerides ½mg=dL=5 (9). Definitions of High Cholesterol Awareness, Treatment, and Control Participants with LDL cholesterol at or greater than the ATP-III risk-specific cut-points and/or who were currently using pharmacologic lipid-lowering therapy were classified as having high LDL cholesterol. Among participants with high levels of LDL cholesterol, those who reported having been told by a doctor or other health professional that their blood cholesterol level was high were classified as being aware of their diagnosis of high LDL cholesterol. The treatment of high LDL cholesterol was identified through selfreported current use of lipid-lowering medication. Treated participants whose LDL cholesterol was lower than the ATP-III risk-specific goals were defined as having controlled their high LDL cholesterol (LDL cholesterol !100 mg/dL

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for those with CHD or CHD risk equivalents, LDL cholesterol !130 mg/dL for those with two or more CHD risk factors, and LDL cholesterol !160 mg/dL for those with 0-1 CHD risk factors). The protocols for NHANES III and NHANES 19992004 were approved by the National Center for Health Statistics of the Centers for Disease Control and Prevention Institutional Review Board. Informed consent was obtained from each NHANES participant. Statistical Analysis Age-standardized mean total-, LDL-, and HDL-cholesterol levels and geometric mean triglyceride levels were calculated for NHANES III and NHANES 19992004, separately. Next, we calculated the age-standardized prevalence of ATP-III-defined categories of total cholesterol (!200, 200239, and >240 mg/dL), LDL cholesterol (!100, 100129, 130159, 160189, and >190 mg/dL), HDL cholesterol (!40, 4059, and >60 mg/dL), and triglycerides (!150 and >150 mg/dL). The age-standardized prevalence of CHD, CHD risk equivalents, and CHD risk factors was determined, and the prevalence of ATP-III risk categories was computed overall and after stratification by age, gender, and race-ethnicity. For these analyses, agestandardization was performed through direct adjustment to the year 2000 U.S. adult population (10). Age-standardized proportions of U.S. adults with high LDL cholesterol who were aware of this condition, were treated with lipid-lowering medication, and who had controlled LDL cholesterol, were calculated for NHANES III and NHANES 19992004, separately, for the overall population and by age, gender, race-ethnicity, and ATPIII risk category. Because of the low number of NHANES III participants achieving LDL cholesterol control (n Z 50) compared to NHANES 19992004 (n Z 381), LDL cholesterol control rates within subgroups were not calculated for 19881994. Prevalence estimates for awareness, treatment, and control of high LDL cholesterol were standardized to the age distribution of participants with high LDL cholesterol in NHANES 19992004. For all analyses, comparisons across NHANES III and NHANES 19992004 were made using t-tests and, within each NHANES survey, were assessed through maximum likelihood estimation using the modified Wald test (11). Two sets of sensitivity analyses were performed. First, we computed the percentage of U.S. adults in 19881994 and 19992004 aware, treated, and with controlled LDL cholesterol using a universal cut-point of LDL cholesterol >160 mg/dL or the use of lipid-lowering medication to define high LDL cholesterol prevalence, and LDL cholesterol !160 mg/dL for control. Second, the definition of high LDL cholesterol was modified incorporating therapeutic

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lifestyle changes, including eating fewer high fat or high cholesterol foods, controlling or losing weight, and/or increasing physical activity to lower blood cholesterol. Using this alternate definition, the age-standardized proportions of U.S. adults with high LDL cholesterol, aware of this condition, treated with lipid-lowering medication or therapeutic lifestyle changes, and with controlled LDL cholesterol either through medication or lifestyle changes was evaluated for NHANES III and NHANES 19992004. SUDAAN (Cary, NC) was used for all analyses to account for the complex sampling design of each NHANES survey, with standard errors estimated by means of Taylor series linearization methods.

RESULTS Compared with 19881994, the age-standardized mean total- and LDL-cholesterol levels were significantly lower in 19992004 (Table 1). Additionally, there was a shift in the distribution of US adults into lower ATP-III-defined total- and LDL-cholesterol groupings. In contrast, significant increases in HDL cholesterol and triglyceride levels occurred between 19881994 and 19992004. TABLE 1. Age-standardized mean/geometric mean cholesterol levels and percentage of U.S. adults by level of total-, LDL-, and HDL-cholesterol in addition to triglycerides in NHANES III and NHANES 1999–2004 NHANES III mean/% (SE)a

NHANES 1999–2004 mean/% (SE)a p values

Total cholesterol, mg/dL Overall mean 204.4 (1.0) 199.4 (0.7) !200 47.7 (1.4) 53.5 (0.9) 200–239 33.4 (1.2) 31.9 (0.9) >240 18.9 (0.8) 14.6 (0.6) LDL cholesterol, mg/dL Overall mean 128.3 (0.9) 120.8 (0.7) !100 22.9 (0.9) 29.1 (0.9) 100–129 31.3 (1.1) 34.3 (0.9) 130–159 27.7 (1.0) 23.7 (0.8) 160–189 12.5 (0.6) 9.7 (0.5) >190 5.6 (0.4) 3.3 (0.3) HDL cholesterol, mg/dL Overall mean 50.7 (0.4) 52.4 (0.4) !40 23.5 (1.1) 19.5 (0.8) 40–59 53.2 (1.1) 53.0 (0.8) >60 23.3 (1.0) 27.6 (0.8) Triglycerides, mg/dL Overall geometric 111.6 (108.2, 115.1) 115.8 (113.6, 118.1) meana !150 70.9 (1.3) 68.7 (0.8) >150 29.1 (1.3) 31.3 (0.8)

!0.001 !0.001 0.317 !0.001 !0.001 !0.001 0.034 0.002 !0.001 !0.001 0.003 0.003 0.883 !0.001 0.050 0.150 0.150

SE Z standard error; LDL Z low-density lipoprotein; HDL Z high-density lipoprotein; NHANES Z National Health and Nutrition Examination Survey. a The geometric mean (95% confidence interval) is given for triglycerides, as the distribution is highly skewed.

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The prevalence of CHD, including risk equivalents, did not significantly change from 19881994 (15.5%) to 19992004 (15.6%; Table 2). Although the prevalence of diabetes increased over this time period, the prevalence of a 10-year risk of CHD O20% decreased. The percentage of the population with at least one CHD risk factor did not change significantly. The prevalence of hypertension was higher and the prevalence of low HDL cholesterol, cigarette smoking and family history of CHD was lower in 19992004 compared with 19881994. Overall, the distribution of the population into ATP-III risk categories did not change substantially from 19881994 to 19992004 (Table 3). In 19992004, the percentage of U.S. adults with two or more CHD risk factors and CHD, including risk equivalents, was higher at older age groupings and in men compared to women. Compared with non-Hispanic blacks and Mexican-Americans, a higher percentage of non-Hispanic whites had two or more CHD risk factors. Also, non-Hispanic blacks were more likely to have CHD or a CHD risk equivalent compared with nonHispanic whites. The prevalence of high LDL cholesterol was 26.6% in 19881994 and 25.3% in 19992004 (Table 4; p Z 0.28). The prevalence of high LDL cholesterol did not change substantially in any subgroups except non-Hispanic blacks and Mexican-Americans, groups which experienced significant reductions (p Z 0.02 and p Z 0.04, respectively). Among the population with high LDL cholesterol, TABLE 2. Age-standardized prevalence of coronary heart disease, coronary heart disease risk equivalents, and coronary heart disease risk factors in NHANES III and NHANES 1999–2004 NHANES NHANES III % (SE) 1999–2004 % (SE) p values CHD or CHD risk equivalents Any CHD or equivalent History of MI History of anginaa History of stroke Diabetes 10-year risk of CHD O 20% CHD risk factors Any risk factor Cigarette smoking Hypertension Older ageb Family history of CHD HDL cholesterol !40 mg/dL HDL cholesterol >60 mg/dL

15.5 (0.8) 3.3 (0.3) 4.3 (0.4) 1.9 (0.2) 6.7 (0.4) 3.9 (0.4)

15.6 (0.7) 3.2 (0.3) 2.7 (0.3) 2.5 (0.3) 8.8 (0.5) 2.6 (0.2)

0.925 0.814 0.001 0.096 0.001 0.004

73.0 (0.9) 26.9 (0.9) 22.7 (0.8) 35.1 (1.6) 16.9 (0.8) 23.5 (1.1) 23.3 (1.0)

73.0 (0.9) 23.6 (0.9) 28.5 (0.7) 38.7 (1.0) 14.8 (0.6) 19.5 (0.8) 27.6 (0.8)

1.00 0.010 !0.001 0.056 0.036 0.003 !0.001

SE Z standard error; NHANES Z National Health and Nutrition Examination Survey; CHD Z coronary heart disease; MI Z myocardial infarction; HDL Z high density lipoprotein. a Angina was defined through the Rose questionnaire for NHANES III and adults >40 years in 2001–2004; for the remainder, angina was assessed by self-report. b Age >45 years for men and >55 years for women.

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awareness of this condition increased from 39.2% to 63.0% (p ! 0.001) and treatment with lipid-lowering medication rose from 11.7% to 40.8% (p ! 0.001). Among individuals aware of their high LDL cholesterol, the percentage receiving treatment increased from 29.6% to 63.6% (p ! 0.001; data not shown). Significant increases in awareness and treatment were present within each subgroup. Among the U.S. adult population with high LDL cholesterol, control rates increased from 4.0% in 19881994 to 25.1% in 19992004 (Fig. 1, top panel; p ! 0.001). In 1999–2004, LDL cholesterol control was higher at older age groupings (p trend ! 0.001), in women compared with men (p Z 0.01), and in non-Hispanic whites compared with non-Hispanic blacks and Mexican-Americans (p Z 0.05 and 0.008, respectively). Persons with zero/one and two or more CHD risk factors were also more likely to control their LDL cholesterol compared with individuals with CHD or CHD risk equivalents (p ! 0.001 and p Z 0.002, respectively). Among the population receiving lipid-lowering medication, LDL cholesterol control rates increased from 34.7% in 19881994 to 60.7% in 19992004 (Fig. 1, bottom panel; p ! 0.001). The only significant difference in LDL cholesterol control rates among the treated population in 19992004 was present across ATP-III risk groupings; individuals with zero/one and two or more CHD risk factors achieved higher LDL cholesterol control rates compared with their counterparts with CHD or a CHD risk equivalent (each p ! 0.001). Sensitivity Analyses To examine whether control rates are truly disparate across ATP-III risk categories, or a result of CHD risk-specific cutpoints, we conducted a sensitivity analysis using a universal cut-point of LDL cholesterol >160 mg/dL and/or use of lipid-lowering medication to define high LDL cholesterol prevalence, and LDL cholesterol !160 mg/dL for control. Using this uniform cut-point, the percentages of those aware, treated, and controlled in 19992004 were 53.3%, 24.4%, and 21.7%, respectively, for those with zero/one CHD risk factors, 63.0%, 40.8%, and 33.1%, respectively, for those with two or more CHD risk factors, and 84.8%, 61.9%, and 56.6%, respectively, of those with CHD or risk equivalents. The prevalence, awareness, treatment and control rates were greater when therapeutic lifestyle changes were included in the definition of high LDL cholesterol. However, the trends over time were markedly similar to those reported in the primary analyses. Specifically, in 19881994 and 19992004, the prevalence of high LDL cholesterol was 34.1% and 32.2%, respectively (p Z 0.08), awareness of

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TABLE 3. Age-standardized prevalence of Adult Treatment Panel III risk categories by age group, sex, and race-ethnicity in NHANES III and NHANES 1999–2004 NHANES III ATP-III Risk Category a

Total Age group, years 20–49 50–64 65þ Sex Male Female Race-ethnicity Non-Hispanic white Non-Hispanic black Mexican-American

a

NHANES 1999–2004 ATP-III Risk Category

0–1 risk factors, without CHD % (SE)

2þ risk factors, without CHD % (SE)

CHD or CHD risk equivalentb % (SE)

0–1 risk factors,a without CHD % (SE)

2þ risk factors,a without CHD % (SE)

CHD or CHD risk equivalentb % (SE)

60.5 (1.1)

24.0 (0.9)

15.5 (0.8)

62.0 (1.1)

22.5 (0.7)

15.6 (0.7)

74.2 (1.3) 43.3 (2.2) 31.9 (1.6)e

18.9 (1.1) 33.7 (1.7) 30.7 (1.7)e

6.9 (0.7) 23.1 (1.5) 37.4 (1.8)e

75.6 (1.1) 45.6 (2.1) 33.0 (1.8)e

17.8 (1.0) 32.6 (1.4) 27.0 (1.5)e

6.6 (0.7) 21.9 (1.7) 40.0 (1.8)e

51.7 (1.6) 68.1 (1.4)e

30.3 (1.4) 18.3 (1.0)e

18.1 (1.0) 13.6 (1.2)c

52.5 (1.6) 70.6 (1.0)e

28.3 (1.2) 17.0 (0.7)e

19.2 (0.9) 12.5 (0.8)e

60.0 (1.4) 59.5 (1.4) 61.5 (1.2)

25.4 (1.0) 20.0 (1.4)d 16.9 (1.2)e

14.6 (0.9) 20.5 (1.0)e 21.6 (1.1)e

61.1 (1.3) 59.9 (1.5) 65.7 (1.3)e

24.2 (0.9) 20.4 (1.1)d 16.7 (1.0)e

14.7 (0.9) 19.8 (1.3)d 17.7 (1.2)

SE Z standard error; NHANES Z National Health and Nutrition Examination Survey; ATP-III Z Adult Treatment Panel III; CHD Z coronary heart disease. a Risk factors include cigarette smoking, hypertension, low HDL cholesterol, family history of CHD, and older age. High HDL cholesterol is a protective CHD risk factor and negates the presence of one CHD risk factor. b CHD or risk equivalents include myocardial infarction, angina, stroke, diabetes mellitus, or the presence of multiple risk factors and calculated 10-year risk of CHD by the Framingham risk equation O20%. c p ! 0.05; dp ! 0.01; ep ! 0.001. (p-values reflect comparisons across age, sex, and race/ethnicity subgroups within the 0–1 risk factors, 2þ risk factors, and CHD or CHD equivalent categories, separately for NHANES III and NHANES 1999–2004.)

this condition was 52.3% and 71.4%, respectively (p ! 0.001), treatment with either lipid-lowering medication or therapeutic lifestyle changes was 48.4% and 65.5%, respectively (p ! 0.001), and control of high LDL cholesterol was 18.1% and 35.6%, respectively (p ! 0.001).

DISCUSSION Although the prevalence of high LDL cholesterol in U.S. adults did not change significantly between 19881994 and 19992004, substantial increases in the awareness, treatment, and control of high LDL cholesterol occurred during this time period. In 19992004, more than half of individuals with high LDL cholesterol were aware of this condition, and a majority of those aware were treated with pharmacologic lipid-lowering medication. However, the most impressive observation may be that, between 19881994 and 19992004, high LDL cholesterol control rates increased 6-fold among the population with high LDL cholesterol and 26 percentage points among participants who were receiving pharmacologic treatment. Improvement in the control of high LDL cholesterol is likely the result of increased emphasis on CHD prevention in the United States. Updated versions of the ATP guidelines incorporating a growing body of clinical evidence were released in 1988, 1993, and 2001 and have been widely disseminated (3, 12, 13). Several generations of statin therapy have been produced, and the tolerability of these and

other lipid-lowering medications has improved significantly (14, 15). These accomplishments aside, high LDL cholesterol remains an important public health issue in the United States. Furthermore, rates of awareness, treatment and control remain suboptimal. The Report of the Outcomes Writing Group of the Minority Health Summit 2003 emphasized disproportionately high rates of cardiovascular disease outcomes and prevalence of cardiovascular risk factors in racial/ethnic minority groups and recommended targeted education, research, and advocacy to better understand and eliminate these disparities (16). Although tremendous improvements in awareness and treatment were noted in all race-ethnicity groups included in the current study, compared with non-Hispanic whites, lower percentages of non-Hispanic blacks and Mexican-Americans were aware, treated and had controlled their LDL cholesterol. These results highlight the importance of the Minority Health Summit Outcomes Writing Group Report recommendations to prepare and disseminate culturally sensitive, tailored educational material and programs for minority populations and underscore the need to identify ‘‘high-risk’’ groups for intervention (16). The differences in LDL cholesterol control rates observed across ATP-III risk categories may be the result of the progressively lower cut-points used in defining LDL cholesterol control for patients with two or more CHD risk factors and CHD or CHD risk equivalents. In sensitivity analyses using a universal cut-point, substantially higher rates of awareness, treatment, and control were noted among patients

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TABLE 4. Age-standardized percentage of U.S. adults in 1988–1994 (NHANES III) and 1999–2004 (NHANES 1999–2004) with high LDL cholesterol, aware of this diagnosis, and currently undertaking drug therapy Awarea

High LDL Cholesterol

Total Age group, years 20–49 50–64 65þ Sex Male Female Race-ethnicity NH-white NH-black MA ATP-III risk category CHD 2þ risk factors 0–1 risk factor

Treateda

P value

NHANES III (n Z 191) % (SE)

NHANES 1999–2004 (n Z 624) % (SE)

P value

63.0 (1.8)

!0.001

11.7 (1.1)

40.8 (1.7)

!0.001

31.3 (3.2) 47.8 (3.0) 37.0 (2.9)d

50.4 (3.6) 70.1 (2.8) 66.5 (2.4)d

!0.001 !0.001 !0.001

8.0 (1.9) 14.1 (1.8) 12.5 (1.7)

25.0 (3.4) 48.0 (2.6) 46.8 (2.4)d

!0.001 !0.001 !0.001

0.28 0.48

35.4 (2.7) 43.2 (2.6)b

58.3 (2.6) 68.6 (2.4)c

!0.001 !0.001

8.5 (1.1) 15.2 (1.9)c

38.9 (2.5) 42.7 (1.9)

!0.001 !0.001

25.8 (0.9) 24.3 (1.6) 23.3 (1.4)b

0.72 0.02 0.04

40.7 (2.6) 30.0 (2.7)c 29.8 (3.6)b

65.3 (2.1) 53.6 (2.9)b 49.6 (3.4)c

!0.001 !0.001 !0.001

12.3 (1.3) 9.0 (1.1) 8.8 (1.8)b

42.4 (2.1) 34.6 (2.7) 30.8 (3.9)b

!0.001 !0.001 !0.001

79.1 (2.1) 35.2 (1.8)d 8.6 (0.5)d

0.12 0.48 0.07

35.9 (2.7) 39.4 (2.8) 54.6 (5.1)c

58.9 (2.6) 61.4 (2.9) 81.6 (2.8)d

!0.001 !0.001 !0.001

10.5 (1.5) 9.6 (1.8) 28.2 (4.6)c

35.2 (2.1) 38.6 (2.7) 65.7 (3.1)d

!0.001 !0.001 !0.001

NHANES III (n Z 1937) % (SE)

NHANES 1999–2004 (n Z 1628) % (SE)

p value

NHANES III (n Z 638) % (SE)

NHANES 1999–2004 (n Z 951) % (SE)

26.6 (0.9)

25.3 (0.8)

0.28

39.2 (2.2)

13.6 (1.0) 42.3 (1.9) 54.2 (1.8)d

12.1 (0.7) 40.6 (1.8) 54.0 (1.8)d

0.22 0.52 0.94

31.6 (1.2) 22.2 (1.2)d

29.9 (1.0) 21.1 (1.0)d

26.3 (1.1) 29.1 (1.2) 26.8 (1.0) 83.7 (2.1) 37.0 (1.8)d 7.2 (0.6)d

SE Z standard error; NHANES Z National Health and Nutrition Examination Survey; LDL Z low-density lipoprotein; NH Z Non-Hispanic; MA ZMexican-American. a Among those with high LDL cholesterol. b p ! 0.05; cp ! 0.01; dp ! 0.001.

with CHD or CHD risk equivalents. These results highlight an interesting paradigm of care; it appears that individuals at highest risk for CHD are receiving more attention and treatment when a uniform high LDL cholesterol cut-point is applied. However, as was displayed in Figure 1, these same individuals are less likely to reach their ATP-III defined LDL cholesterol goal compared to their counterparts in lower risk categories. A recent publication reporting trends in cholesterol and triglyceride levels showed significant decreases in total- and LDL-cholesterol and no significant changes in HDL cholesterol and triglyceride levels (17). Other studies also have estimated the prevalence of high total cholesterol, awareness, treatment, and control in the U.S. adult population using NHANES data (18–20). For example, Ford and colleagues defined high total cholesterol as >200 mg/dL and/or use of lipid-lowering medication, and reported a prevalence of awareness, treatment and control of high total cholesterol of 35.0%, 12.0%, and 5.4%, respectively, using data from NHANES 1999-2000 (19). Another recent publication examined the prevalence of screening and awareness of high blood cholesterol in the U.S. adult population using data from 1999 to 2002, with high blood cholesterol being defined as a total cholesterol level of >240 mg/dL and/or use of lipid-lowering medication. In that study, prevalence of high total cholesterol of 24.6%, and awareness of this condition of 63.3% was reported (20). Although congruent with the previous findings, the current study extends those studies

to utilize NHANES data through 2004, the National Cholesterol Education Program’s ATP-III guidelines and LDL cholesterol levels in examining trends and the burden of high blood cholesterol and awareness, treatment and control rates in US adults. The results of the current study need to be interpreted in the context of its limitations. Misclassification of participants into ATP-III risk categories was possible, as the assessment of some CHD risk factors and a history of CHD relied on self-report. Also, family history of CHD was limited to myocardial infarction and/or angina in first-degree relatives before the age of 50 years, and thus, may underestimate the percentage of U.S. adults with a family history of premature CHD. Additionally, the assessment of angina was performed using different methods over the survey years included in the analysis and the reduction in history of angina may be the spurious result of different methods of assessment. However, the results of the current study did not change materially after excluding angina as a CHD event (data not shown). The current study uncovered several important findings. First, the percentage of the U.S. adult population with high LDL cholesterol did not decline between 19881994 and 19992004. Second, a greater percentage of U.S. adults with high LDL cholesterol were aware of this condition, receiving treatment, and achieving the ATP-III-defined goal for control of their high LDL cholesterol in 19992004, compared with 19881994. However, LDL cholesterol awareness, treatment, and control rates remain suboptimal,

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Among Persons with High LDL Cholesterol

100% NHANES III NHANES 1999-2004

% Control

80%

58%‡

60%

40% 29%

25%‡ 20%

30%‡ 23%

28%*

27%

26%† 17%*

14%

17%†

15%

4% 0%

NHANES NHANES III 99-04 Overall

50-64 20-49 65+ Age group, years

Men Women Sex

NHW

NHB MA Race/Ethnicity

0-1 2+ CHD ATP III risk category

Among Treated Population

100%

89%‡

% Control

80% 61%‡

60%

40%

56%

61%

66%

65% 57%

65%‡

62% 52%

56% 41%

35%

20%

0%

NHANES NHANES III 99-04 Overall

20-49 65+ 50-64 Age group, years

Men Women Sex

NHW NHB MA Race/Ethnicity

2+ CHD 0-1 ATP III risk category

FIGURE 1. Age-standardized LDL cholesterol control rates among U.S. adults with high LDL cholesterol and among the treated population in NHANES III and NHANES 1999–2004 and by age group, sex, race-ethnicity, and ATP-III risk category as estimated by NHANES 1999–2004. LDL Z low density lipoprotein; NHANES Z National Health and Nutrition Examination Survey; ATP-III Z Adult Treatment Panel III; NHW Z Non-Hispanic white; NHB Z Non-Hispanic black; MA Z Mexican-American. *p ! 0.05; yp ! 0.01; zp ! 0.001 for comparison overall between NHANES III and NHANES 1999–2004 and among subgroups for NHANES 1999–2004.

and younger adults, men, and non-Hispanic blacks and Mexican-Americans have especially low rates of LDL cholesterol control. Despite tremendous progress, high LDL cholesterol remains a highly prevalent CHD risk factor. Continued efforts are needed to reduce the burden of high LDL cholesterol in the US population and increase awareness, treatment and control of this important and modifiable CHD risk factor.

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