Trends in Cardiovascular Disease Risk Factors by Obesity Level in Adults in the United States, NHANES 1999-2010
Objective
To assess whether trends in cardiovascular disease (CVD) risk factors by among overweight and obese US adults have improved.
Methods
The study included 10,568 adults 18 years and older who participated in National Health and Nutrition Examination Survey 1999-2010. CVD risk factors included diabetes (self-reported diagnosis, glycated hemoglobin ≥6.5%, or fasting plasma glucose ≥126mg/dl), hypertension (treatment or blood pressure ≥140/90 mmHg), dyslipidemia (treatment or non-HDL cholesterol ≥160 mg/dl), and smoking (self-report or cotinine levels ≥10 ng/ml). The prevalence and temporal trends of CVD risk factors for each BMI group were estimated.
Results
In 2007-2010, the prevalence of diabetes, hypertension, and dyslipidemia was highest among obese (18.5%, 35.7%, 49.7%, respectively) followed by overweight (8.2%, 26.4%, 44.2%, respectively) and normal weight adults (5.4%, 19.8%, 28.6%, respectively). Smoking exposure was highest among normal weight (29.8%) followed by overweight (24.8%) and obese adults (24.6%). From 1999-2002 to 2007-2010, untreated hypertension decreased among obese and overweight adults and untreated dyslipidemia decreased for all weight groups. There were no significant temporal changes in smoking across BMI groups.
Conclusions
Despite decreases in untreated risk factors, it is important to improve the CVD risk profile of overweight and obese US adults.
Introduction
In 2008-2010, over 35% of adults 18 years and older in the United Stat were obese (1) and there is evidence that overweight and obesity among adults is associated with increased risk of cardiovascular disease (CVD) (2,3) and an increased risk of diabetes (4). Although there appears to be a leveling off of obesity levels in the United States (1), it is unknown whether the health burdens associated with higher weight may be continuing to increase (5).
Using data from national health surveys from 1960 to 2000, Gregg and colleagues (6) reported a significant decline in major cardiovascular risk factors, except diabetes, across all BMI levels. However, over this time period, the prevalence of undiagnosed diabetes decreased, particularly among the highest weight group (7). Whether these trends have continued in the past decade is unknown. Therefore, we analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1999 through 2010 to examine trends in the prevalence and diagnosis or treatment of cardiovascular risk factors by weight status among adults in the United States.
Methods
The NHANES is a cross-sectional survey of the health and nutritional status of the US civilian, noninstitutionalized population conducted by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC) (8). Participants were randomly selected through a complex, multistage cluster sampling probability design. The NHANES collects data through interviews in participants' homes and conducts medical examinations and laboratory assessments in the Mobile Examination Center. For this report, we analyzed 1999-2010 NHANES data on participants who were 18 years or older and had complete measurements of CVD risk factors and anthropometry (n = 33,560). NHANES is conducted in independent, 2-year cycles. Response rates for participation in both the interview and physical examination were similar across cycles and ranged from 75 to 80% (9). The survey protocol was approved by the NCHS institutional review board. Written informed consent was obtained from all participants aged ≥18 years. NHANES methods and protocols for the questionnaires, laboratory, and examination have been described extensively (8).
Demographics included age, sex, and race/ethnicity. Race/ethnicity was based on self-report and categorized as non-Hispanic white, non-Hispanic black, Mexican American, or Hispanic and non-Hispanic other. Family income was included as a percentage of the established poverty income ratio (PIR), calculated as the family's income divided by the federal poverty level (defined as 100% in the categories below). PIR was categorized as <1.50, 1.50 to 3.50, and ≥3.50. Participants were considered to have health insurance if they reported to be covered by a health insurance plan at the time of the survey.
BMI groups
Participants were categorized based on BMI group as 18 to <25 kg/m (normal weight), BMI 25 to <30 kg/m (overweight), and BMI ≥ 30 kg/m (obese). Participants with BMI ≥ 35 kg/m (morbidly obese) are included in the obese category and presented separately. Underweight participants (BMI < 18.5 kg/m ) were excluded (n = 606).
Cardiovascular disease risk factors
Information regarding presence of cardiovascular risk factors was obtained during the NHANES interview and examination. Four CVD risk factors were included in the analysis: diabetes, hypertension, dyslipidemia, and smoking.
Blood pressure (BP) was measured during the NHANES physical examination in the mobile examination center. Up to three BP measurements were taken by a physician after a 5-minute rest following the NHANES standard protocol and the average of the measurements was used for the analysis. Non-HDL cholesterol was used for serum lipid levels and was calculated as total cholesterol minus HDL cholesterol.
Hypertension was defined as self-report of use of antihypertensive medications or systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg. Among those without self-report of antihypertensive medication use, untreated hypertension was defined as systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg (10).
Total dyslipidemia was defined as self-report of use of medications to lower cholesterol or non-HDL cholesterol ≥ 160 mg/dl. Among adults with no self-report of cholesterol-lowering medications, untreated dyslipidemia was defined as non-HDL cholesterol ≥ 160 mg/dl (11,12).
Among participants 20 years and older, self-reported smoking was defined as having smoked at least 100 cigarettes in a lifetime and report of current smoking. Among participants 18 and 19 years old, self-reported smoking was defined as report of use of nicotine or tobacco products in the last 5 days. Moderate to heavy smoking exposure was defined based on cotinine levels ≥ 10 ng/ml, regardless of self-reported smoking.
Fasting plasma glucose was measured on participants randomly selected for the morning exam who reported fasting between 8 and 24 hours (1999-2002, n = 4328; 2003-2006, n = 4305; 2007-2010, n = 5085). Analysis of diabetes was restricted to this subsample. Total diabetes was defined by self-report of diagnosis by health care professional or glycated hemoglobin (A1c) level ≥ 6.5% or fasting plasma glucose ≥ 126 mg/dl (13). Among those without self-report of diabetes, undiagnosed diabetes was defined as an A1c level ≥ 6.5% or fasting plasma glucose ≥ 126 mg/dl. We did not distinguish between type 1 and type 2 diabetes.
Statistical analysis
Sample design variables and weights were used to produce nationally representative estimates that accounted for the NHANES complex survey design, including its stratified multistage cluster sampling. We used SAS 9.3 and SUDAAN 11 software (Research Triangle Institute, Research Triangle Park, NC) for the statistical analyses.
To assess trends over time and produce reliable estimates, we grouped data into 4-year periods: 1999-2002, 2003-2006, 2007-2010 (14). The 4-year time periods were compared based on demographics and measures of obesity. Prevalence of each risk factor was calculated overall and for each BMI group. We calculated the absolute change in prevalence over a decade as the percent estimate for 2007-2010 minus the percent estimate for 1999-2002. Among those with a risk factor, the percent undiagnosed or untreated was calculated. Among adults who fasted and completed the morning examination, the prevalence of adults with 1, 2, or ≥3 risk factors within each BMI group was also calculated. As there was little difference between self-reported smoking and moderate to heavy smoking exposure based on cotinine, self-reported smoking was included in the count of the number of risk factors.
Results were age standardized to the 2000 US census population using the direct method with three age groups: 18-44, 45-64, and ≥ 65 years.
BMI groups
Participants were categorized based on BMI group as 18 to <25 kg/m (normal weight), BMI 25 to <30 kg/m (overweight), and BMI ≥ 30 kg/m (obese). Participants with BMI ≥ 35 kg/m (morbidly obese) are included in the obese category and presented separately. Underweight participants (BMI < 18.5 kg/m ) were excluded (n = 606).
Cardiovascular disease risk factors
Information regarding presence of cardiovascular risk factors was obtained during the NHANES interview and examination. Four CVD risk factors were included in the analysis: diabetes, hypertension, dyslipidemia, and smoking.
Blood pressure (BP) was measured during the NHANES physical examination in the mobile examination center. Up to three BP measurements were taken by a physician after a 5-minute rest following the NHANES standard protocol and the average of the measurements was used for the analysis. Non-HDL cholesterol was used for serum lipid levels and was calculated as total cholesterol minus HDL cholesterol.
Hypertension was defined as self-report of use of antihypertensive medications or systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg. Among those without self-report of antihypertensive medication use, untreated hypertension was defined as systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg (10).
Total dyslipidemia was defined as self-report of use of medications to lower cholesterol or non-HDL cholesterol ≥ 160 mg/dl. Among adults with no self-report of cholesterol-lowering medications, untreated dyslipidemia was defined as non-HDL cholesterol ≥ 160 mg/dl (11,12).
Among participants 20 years and older, self-reported smoking was defined as having smoked at least 100 cigarettes in a lifetime and report of current smoking. Among participants 18 and 19 years old, self-reported smoking was defined as report of use of nicotine or tobacco products in the last 5 days. Moderate to heavy smoking exposure was defined based on cotinine levels ≥ 10 ng/ml, regardless of self-reported smoking.
Fasting plasma glucose was measured on participants randomly selected for the morning exam who reported fasting between 8 and 24 hours (1999-2002, n = 4328; 2003-2006, n = 4305; 2007-2010, n = 5085). Analysis of diabetes was restricted to this subsample. Total diabetes was defined by self-report of diagnosis by health care professional or glycated hemoglobin (A1c) level ≥ 6.5% or fasting plasma glucose ≥ 126 mg/dl (13). Among those without self-report of diabetes, undiagnosed diabetes was defined as an A1c level ≥ 6.5% or fasting plasma glucose ≥ 126 mg/dl. We did not distinguish between type 1 and type 2 diabetes.
Statistical analysis
Sample design variables and weights were used to produce nationally representative estimates that accounted for the NHANES complex survey design, including its stratified multistage cluster sampling. We used SAS 9.3 and SUDAAN 11 software (Research Triangle Institute, Research Triangle Park, NC) for the statistical analyses.
To assess trends over time and produce reliable estimates, we grouped data into 4-year periods: 1999-2002, 2003-2006, 2007-2010 (14). The 4-year time periods were compared based on demographics and measures of obesity. Prevalence of each risk factor was calculated overall and for each BMI group. We calculated the absolute change in prevalence over a decade as the percent estimate for 2007-2010 minus the percent estimate for 1999-2002. Among those with a risk factor, the percent undiagnosed or untreated was calculated. Among adults who fasted and completed the morning examination, the prevalence of adults with 1, 2, or ≥3 risk factors within each BMI group was also calculated. As there was little difference between self-reported smoking and moderate to heavy smoking exposure based on cotinine, self-reported smoking was included in the count of the number of risk factors.
Results were age standardized to the 2000 US census population using the direct method with three age groups: 18-44, 45-64, and ≥ 65 years.
Results
Participants' characteristics overall and by survey period are reported in Table 1. Overall, there was little change in the demographics from 1999-2002 to 2007-2010. However, over this period, the percent of adults 18-44 years decreased (55.2-48.9%), percent of obese adults increased (30.1-34.3%), and the percent of morbidly obese adults increased (12.4-14.7%).
Table 1
| Total | 1999-2002 | 2003-2006 | 2007-2010 | |
|---|---|---|---|---|
| Sample size | 33,560 | 10,568 | 10,637 | 12,355 |
| Age, mean years (SE) | 45.1 (0.22) | 44.2 (0.32) | 45.4 (0.47) | 45.9 (0.33) |
| Age group, % (SE) | ||||
| 18-44 years | 51.6 (0.62) | 55.2 (0.94) | 51.1 (1.29) | 48.9 (0.89) |
| 45-64 years | 32.3 (0.47) | 29.9 (0.84) | 32.4 (0.91) | 34.5 (0.64) |
| 65 years and older | 16.1 (0.37) | 14.9 (0.50) | 16.6 (0.82) | 16.6 (0.53) |
| Male, % (SE) | 48.2 (0.25) | 48.0 (0.46) | 48.1 (0.43) | 48.3 (0.40) |
| Race/ethnicity, % (SE) | ||||
| Mexican American or Hispanic | 13.0 (0.99) | 14.0 (2.02) | 11.5 (1.32) | 13.6 (1.74) |
| Non-Hispanic black | 11.3 (0.70) | 10.9 (1.21) | 11.5 (1.35) | 11.5 (1.05) |
| Non-Hispanic other | 5.6 (0.36) | 4.7 (0.65) | 5.4 (0.46) | 6.5 (0.75) |
| Non-Hispanic white | 70.1 (1.28) | 70.4 (1.82) | 71.6 (2.20) | 68.4 (2.48) |
| Poverty Income Ratio category, % (SE)a | ||||
| <1.50 | 25.5 (0.75) | 26.8 (1.54) | 23.2 (1.20) | 26.4 (1.16) |
| 1.50 to <3.50 | 32.4 (0.58) | 31.7 (1.05) | 34.4 (1.08) | 30.9 (0.89) |
| ≥3.50 | 42.2 (0.93) | 41.5 (1.84) | 42.3 (1.56) | 42.6 (1.42) |
| Have Health Insurance, % (SE) | 80.9 (0.51) | 81.6 (0.89) | 81.4 (1.02) | 79.7 (0.74) |
| BMI, mean kg/m (SE) | 28.3 (0.07) | 27.9 (0.13) | 28.3 (0.14) | 28.5 (0.10) |
| BMI group, % (SE) | ||||
| 18.5 to <25 kg/m2 | 32.0 (0.46) | 33.9 (0.83) | 32.0 (0.82) | 30.3 (0.75) |
| 25 to <30 kg/m2 | 33.5 (0.40) | 34.0 (0.79) | 33.0 (0.68) | 33.6 (0.60) |
| ≥30 kg/m2 | 32.6 (0.49) | 30.1 (0.89) | 33.1 (0.92) | 34.3 (0.71) |
| ≥35 kg/m2 | 13.6 (0.33) | 12.4 (0.66) | 13.5 (0.62) | 14.7 (0.45) |
SE, standard error.
The age-standardized prevalence of each cardiovascular risk factor for each survey period overall and by weight status group is presented in Table 2. In 2007-2010, among normal weight adults, the prevalence of total diabetes was 5.4% and the prevalence of total hypertension, total dyslipidemia, and total smoking exposure was 19.8%, 28.6%, and 29.8%, respectively. Among normal weight adults from 1999-2002 to 2007-2010, there was no significant change in the prevalence of total diabetes, hypertension, or smoking exposure.
Table 2
| 1999-2002 | 2003-2006 | 2007-2010 | Percentage point change from 1999-2002 to 2007-2010, % (95% CI) | |
|---|---|---|---|---|
| Total populationc | ||||
| Sample size | 10,132 | 10,436 | 12,175 | |
| Fasting sample sized | 4,426 | 4,406 | 5,188 | |
| Total diabetesd | 9.4 (8.2, 10.7) | 10.2 (9.0, 11.4) | 11.0 (9.9, 12.2) | 1.6 (0.01, 3.2) |
| Undiagnosed diabetesd | 3.4 (2.8, 4.0) | 3.2 (2.5, 4.0) | 3.7 (3.1, 4.3) | 0.3 (−0.5, 1.1) |
| Total hypertension | 27.8 (26.2, 29.4) | 28.7 (27.3, 30.1) | 28.6 (27.6, 29.6) | 0.8 (−1.1, 2.7) |
| Untreated hypertension | 10.9 (9.7, 12.1) | 9.3 (8.3, 10.3) | 7.3 (6.7, 7.8) | −3.6 (−4.9, −2.3) |
| Total dyslipidemia | 41.1 (39.7, 42.5) | 39.8 (38.5, 41.2) | 40.4 (39.2, 41.7) | −0.7 (−2.5, 1.1) |
| Untreated dyslipidemia | 32.5 (31.1, 33.9) | 27.5 (26.3, 28.7) | 26.0 (24.9, 27.0) | −6.5 (−8.2, −4.8) |
| Self-reported smoking | 27.8 (25.8, 29.8) | 30.2 (28.2, 32.1) | 27.1 (25.4, 28.7) | −0.7 (−3.2, 1.8) |
| Moderate to heavy smoking exposure | 28.6 (26.3, 30.8) | 29.0 (26.8, 31.1) | 26.0 (24.1, 28.0) | −2.6 (−5.5, 0.3) |
| Normal weight | ||||
| Sample size | 3,325 | 3,282 | 3,385 | |
| Fasting sample sized | 1,486 | 1,362 | 1,441 | |
| Total diabetesd | 5.1 (3.5, 6.8) | 5.1 (3.4, 6.8) | 5.4 (3.8, 6.9) | 0.3 (−2.0, 2.5) |
| Undiagnosed diabetesd | 1.3 (0.7, 1.9) | 1.5 (0.8, 2.2) | 1.6 (0.8, 2.4) | 0.3 (−0.8, 1.3) |
| Total hypertension | 18.7 (17.0, 20.4) | 20.2 (8.6, 21.7) | 19.8 (18.1, 21.6) | 1.12 (−1.3, 3.5) |
| Untreated hypertension | 8.7 (7.5, 9.8) | 8.0 (6.7, 9.3) | 7.4 (6.4, 8.3) | −1.3 (−2.8, 0.2) |
| Total dyslipidemia | 29.4 (27.8, 31.0) | 26.8 (24.7, 29.0) | 28.6 (27.2, 30.0) | −0.8 (−.9, 1.3) |
| Untreated dyslipidemia | 23.5 (21.7, 25.2) | 18.7 (16.8, 20.6) | 19.0 (17.3, 20.7) | −4.5 (−6.9, 22.1) |
| Self-reported smoking | 31.5 (28.0, 35.1) | 33.6 (31.1, 36.3) | 29.5 (26.7, 32.2) | −2.1 (−6.5, 2.4) |
| Moderate to heavy smoking exposure | 32.4 (28.6, 36.2) | 32.3 (29.6, 35.0) | 28.8 (25.9, 31.6) | −2.0 (−5.3, 1.2) |
| Overweight | ||||
| Sample size | 3,525 | 3,494 | 4,102 | |
| Fasting sample sized | 1,548 | 1,451 | 1,768 | |
| Total diabetesd | 8.2 (6.3, 10.0) | 7.6 (6.2, 9.0) | 8.2 (6.5, 9.9) | 0.01 (−2.5, 2.5) |
| Undiagnosed diabetesd | 2.9 (2.1, 3.7) | 2.6 (1.7, 3.6) | 3.1 (2.3, 3.9) | 0.2 (−0.9, 1.4) |
| Total hypertension | 26.7 (24.4, 29.1) | 27.3 (25.2, 29.4) | 26.4 (24.7, 28.0) | −0.4 (−3.2, 2.5) |
| Untreated hypertension | 11.4 (9.4, 13.4) | 9.7 (8.1, 11.3) | 7.2 (6.2, 8.2) | −4.2 (−6.5, 21.9) |
| Total dyslipidemia | 47.6 (45.6, 49.7) | 45.8 (43.2, 48.3) | 44.2 (42.5, 46.0) | −3.4 (−6.3, 20.5) |
| Untreated dyslipidemia | 38.1 (35.5, 40.7) | 33.6 (31.5, 35.8) | 30.6 (29.0, 32.3) | −7.5 (−10.5, 24.5) |
| Self-reported smoking | 28.0 (26.0, 30.1) | 29.2 (26.7, 31.6) | 27.4 (25.1, 29.8) | −0.3 (−3.4, 2.8) |
| Moderate to heavy smoking exposure | 27.7 (25.4, 29.9) | 27.8 (25.0, 30.5) | 26.0 (23.7, 28.3) | −1.7 (−4.9, 1.6) |
| Obese | ||||
| Sample size | 3,083 | 3,465 | 4,476 | |
| Fasting sample sized | 1,294 | 1,492 | 1,876 | |
| Total diabetesd | 16.0 (13.01, 18.8) | 17.4 (14.8, 20.0) | 18.5 (16.6,20.4) | 2.5 (−0.9, 5.9) |
| Undiagnosed diabetesd | 6.2 (4.8, 7.7) | 5.8 (4.1, 7.4) | 6.6 (5.2, 8.0) | 0.4 (−1.6, 2.4) |
| Total hypertension | 37.5 (35.1, 39.9) | 38.4 (36.2, 40.6) | 35.66 (37.3, 40.1) | −1.9 −4.6, 0.9) |
| Untreated hypertension | 12.5 (10.2, 14.9) | 10.4 (9.1, 11.8) | 7.96 (6.9, 9.0) | −4.6 (−7.1, 22.0) |
| Total dyslipidemia | 50.7 (48.4, 53.0) | 48.7 (46.2, 51.2) | 49.74 (47.4, 52.0) | 0.9 (−4.1, 2.3) |
| Untreated dyslipidemia | 40.2 (37.8, 42.6) | 32.1 (29.8, 34.9) | 30.55 (28.5, 32.6) | −9.6 (−12.5, 26.6) |
| Self-reported smoking | 24.8 (22.1, 27.4) | 27.5 (25.0, 30.0) | 24.5 (22.9, 26.1) | −0.3 (−3.4, 2.8) |
| Moderate to heavy smoking exposure | 25.1 (22.5, 27.9) | 26.6 (24.1, 29.0) | 23.1 (21.3, 25.0) | −2.0 (−5.3, 1.2) |
| Morbidly obese | ||||
| Sample size | 1,257 | 1,422 | 1,939 | |
| Fasting sample sized | 530 | 632 | 797 | |
| Total diabetesd | 21.6 (16.7, 26.6) | 23.5 (18.9, 28.1) | 23.2 (19.9, 26.5) | 1.6 (−4.3, 7.4) |
| Undiagnosed diabetesd | 7.6 (5.1, 10.2) | 8.5 (5.1, 12.0) | 9.3 (6.6, 12.0) | 1.7 (−2.0, 5.4) |
| Total hypertension | 42.4 (28.5, 46.3) | 44.5 (41.6, 47.4) | 44.4 (42.1, 46.7) | 1.98 (−2.5, 6.4) |
| Untreated hypertension | 12.0 (8.7, 15.3) | 9.9 (8.2, 11.7) | 7.4 (5.5, 9.0) | −2.6 (8.3, 20.8) |
| Total dyslipidemia | 46.6 (43.4, 49.8) | 47.3 (44.3, 50.3) | 47.7 (44.6, 50.9) | 1.1 (−3.3, 5.6) |
| Untreated dyslipidemia | 36.3 (33.0, 39.7) | 29.7 (26.7, 32.8) | 27.7 (25.0, 30.4) | −6.6 (−11.1, −2.1) |
| Self-reported smoking | 22.4 (19.3, 25.6) | 24.6 (21.0, 28.2) | 23.0 (20.6, 25.3) | 0.5 (−3.3, 4.4) |
| Moderate to heavy smoking exposure | 22.6 (18.7, 26.5) | 24.1 (20.5, 27.6) | 21.4 (19.0, 23.8) | −1.2 (−5.8, 3.3) |
Normal weight = BMI 18.5 to <25 kg/m; overweight = BMI 25 to <30 kg/m; obese = BMI ≥ 30 kg/m; morbidly obese = BMI ≥ 35 kg/m.
Among overweight adults, the prevalence of each cardiovascular risk factor, except for smoking exposure, was higher than among normal weight adults. In this group, from 1999-2002 to 2007-2010, there was no significant change in the prevalence of total diabetes, hypertension, or smoking exposure, but dyslipidemia decreased significantly (−3.4 percentage points [ppt], 95% confidence interval [CI] −6.3, −0.5).
In general and throughout the time period, the prevalence of total diabetes, hypertension, and dyslipidemia were higher among adults who were obese than those who were overweight or normal weight, while smoking exposure (either based on self-report or cotinine levels) was lower. Among adults who were obese, there was no significant change from 1999-2002 to 2007-2010 for total diabetes, hypertension, dyslipidemia, or total smoking exposure. There was also no significant change for undiagnosed diabetes. However, there was a significant decrease for untreated hypertension (24.6 ppt, 95% CI −7.1, −2.0) and untreated dyslipidemia (−9.6 ppt, 95% CI −12.5, −6.6).
Among the obese adults, those who were morbidly obese (BMI ≥ 35 kg/m ) had an even higher prevalence of diabetes, hypertension, and dyslipidemia. In this group, there were also significant changes between 1999-2002 and 2007-2010 in risk factors for untreated hypertension (−4.6 ppt, 95% CI −8.3, −0.8) and dyslipidemia (−6.6 ppt, 95% CI −11.1, −2.1).
Figure 1 presents the proportion of adults with undiagnosed diabetes among total diabetes or untreated hypertension among total hypertension or untreated dyslipidemia among total dyslipidemia by BMI status across time periods. The proportion of undiagnosed diabetes was approximately 30% for all BMI groups and there was not a consistent pattern of increase or decrease over time. The proportion of untreated hypertension among adults with hypertension and untreated dyslipidemia among adults with dyslipidemia did not change among normal weight adults. The proportions of untreated hypertension across weight groups decreased from 51 to 39% among overweight adults, from 39.7 to 26.8% among obese adults, and from 34 to 21% among morbidly obese adults. The proportions of untreated dyslipidemia also decreased for all weight groups with the larger decreases among the obese (9.6 ppt) and morbidly obese adults (6.5 ppt).
Proportion (age standardized to the 2000 US population using the following age groups: 18-44, 45-64, and ≥65 years) of undiagnosed or untreated among total cardiovascular disease risk group overall and by body mass index group among adults 18 years and older, National Health and Nutrition Examination Surveys 1999 to 2010. *Estimates for normal weight participants not presented due to small sample size (<150) and relative standard error <35%. Normal weight = BM 18.5 to <25 kg/m; overweight = BMI 25 to <30 kg/m; obese = BMI ≥ 30 kg/m; morbidly obese = BMI ≥ 35 kg/m Proportion of undiagnosed diabetes among adults with total diabetes fasting in morning exam. Proportion of untreated hypertension among adults with total hypertension. Proportion of untreated dyslipidemia among adults with total dyslipidemia. Total diabetes = self-report of diagnosis by health care professional or A1c level ≥ 6.5% or fasting plasma glucose ≥ 126 mg/dl Undiagnosed diabetes = no self-report and A1c level ≥ 6.5% or fasting plasma glucose ≥ 126 mg/dl. Total hypertension = self-report of antihypertensive medications or blood pressure ≥ 140/90 mmHg; Untreated hypertension = no self-report of antihypertensive medications and blood pressure ≥ 140/90 mmHg. Total dyslipidemia = self-report of medications to lower cholesterol or non-HDL cholesterol ≥ 160 mg/dl; Untreated dyslipidemia = no report of cholesterol lowering medications and non-HDL cholesterol ≥ 160 mg/dl.
Table 3 presents the age standardized prevalence for 1, 2, and ≥3risk factors for CVD by BMI status. In 2007-2010, adults who were obese had the highest prevalence of ≥3 risk factors (13.5%) followed by overweight adults (5.5%) and normal weight adults (3.2%). Morbidly obese adults had a 16.5% prevalence of ≥3 CVD risk factors. From 1999-2002 to 2007-2010, there was no statistically significant change in the prevalence of 1, 2, or ≥3 risk factors for normal weight or overweight adults. For the obese and morbidly obese adults, there was a significant increase in the prevalence of ≥3 risk factors (3.1 ppt 95% CI 0.5, 5.6, and 5.3 ppt 95% CI 0.7, 10.0).
Table 3
| 1999-2002 | 2003-2006 | 2007-2010 | Percentage point change from 1999-2002 to 2007-2010, % (95% CI) | |
|---|---|---|---|---|
| Totalc | ||||
| Sample size | 4,426 | 4,406 | 5,188 | |
| 1 CVD risk factor | 38.4 (36.3, 40.6) | 37.8 (36.0, 39.6) | 37.8 (35.6, 39.9) | −0.6 (−3.6, 2.4) |
| 2 CVD risk factors | 25.0 (23.0, 27.1) | 22.3 (20.6, 24.0) | 21.1 (19.5, 22.7) | −3.9 (−6.5, 21.3) |
| ≥3 CVD risk factors | 6.6 (5.6, 7.6) | 8.3 (7.1, 9.4) | 7.7 (6.9, 8.6) | −1.1 (−0.2, 2.4) |
| Normal weight | ||||
| Sample size | 1,484 | 1,361 | 1,441 | |
| 1 CVD risk factor | 38.1 (35.6, 40.6) | 39.0 (36.4, 41.5) | 36.2 (32.6, 39.9) | −1.8 (−6.3, 2.6) |
| 2 CVD risk factors | 18.8 (16.0, 21.6) | 18.7 (16.5, 21.0) | 16.7, (13.9, 19.4) | −2.2 (−6.0,1.7) |
| ≥3 CVD risk factors | 3.5 (1.9, 5.1) | 3.5 (2.1, 4.9) | 3.2 (2.4, 4.0) | −0.3 (−2.1, 1.4) |
| Overweight | ||||
| Sample size | 1,548 | 1,450 | 1,766 | |
| 1 CVD risk factor | 40.7 (37.2, 44.2) | 39.9 (37.2, 42.6) | 41.8 (38.5, 45.0) | 1.1 (−3.7, 5.8) |
| 2 CVD risk factors | 27.4 (24.3, 30.5) | 21.3 (18.8, 23.9) | 22.3 19.8, 24.8) | −5.1 (−9.1, −1.2) |
| ≥3 CVD risk factors | 6.0 (4.8, 7.2) | 7.0 (5.3, 8.7) | 5.5 (4.6, 6.5) | −0.4 (−1.9, 1.1) |
| Obese | ||||
| Sample size | 1,294 | 1,492 | 1,876 | |
| 1 CVD risk factor | 37.1 (33.5, 40.7) | 34.9 (31.1, 38.7) | 36.0 (33.5, 38.5) | −1.1 (−5.5, 3.2) |
| 2 CVD risk factors | 31.0 (27.3, 34.6) | 27.1 (23.2, 30.9) | 25.1 (22.4, 27.7) | −5.9 (−10.4, −1.5) |
| ≥3 CVD risk factors | 10.4 (8.4, 12.4) | 14.0 (12.3, 16.3) | 13.5 (11.9, 15.1) | 3.1 (0.5, 5.6) |
| Morbidly obese | ||||
| Sample size | 530 | 632 | 797 | |
| 1 CVD risk factor | 35.7 (30.6,40.9) | 35.3 (29.1, 41.5) | 30.3 (26.3, 34.4) | −5.4 (−11.9, 1.1) |
| 2 CVD risk factors | 31.3 (26.5, 36.1) | 27.7 (20.7, 34.8) | 26.7 (22.6, 30.7) | −4.6 (−10.8, 1.7) |
| ≥3 CVD risk factors | 11.2 (7.4, 15.1) | 16.5 (12.8, 20.2) | 16.5 (13.9, 19.2) | 5.3 (0.7, 10.0) |
Normal weight = BMI 18.5 to <25 kg/m; overweight = BMI 25 to <30 kg/m; obese = BMI ≥ 30 kg/m; morbidly obese = BMI ≥ 35 kg/m.
Discussion
The prevalence of cardiovascular risk factors remains high among all adults and increases as people become overweight or obese. In 2007-2010, over 18% of obese adults had diabetes, 36% had hypertension, and 50% had dyslipidemia. With the exception of total smoking exposure, the prevalence of cardiovascular risk factors was highest among obese adults followed by overweight and normal weight adults. The prevalence of cardiovascular risk factors among morbidly obese adults, a subgroup of obese adults, was even higher.
Despite the increase in the prevalence of obese adults in the US population, the prevalence of CVD risk factors has remained the same or declined over the past decade. This decline continues declines reported since the 1960s (6,15-19). More importantly, the proportion of untreated hypertension and untreated dyslipidemia among those with hypertension or dyslipidemia declined between 1999-2002 and 2007-2010. Of concern is the finding that among overweight or obese people the proportion of undiagnosed diabetes has not changed significantly in this time period and it remains similar to previous reports (7).
The decrease in prevalence with untreated hypertension and untreated dyslipidemia may be an indication that adults are getting screened and treated for these conditions, regardless of weight status. The indication that the decrease is greater among obese adults may indicate that these individuals are more likely to be screened and tested for CVD risks. Antihypertension medication use has increased in the United States in the past decade although control levels are still suboptimal (20). This supports our observation of decrease in untreated hypertension over this same time period regardless of weight status. Although the prevalence of hypertension differed by weight status, there was no change in the prevalence of hypertension, regardless of weight status. This lack of change in prevalence has been reported previously (21). The hypertension definition includes self-report of medication use or elevated BP. These results suggest that individuals are more likely to be treated for hypertension. This observation may suggest a shift to the left in the BP distribution and decrease of BP levels in the US population. Our results with dyslipidemia and elevated non-HDL cholesterol correspond to previously reported trends that examined the mean levels of lipids among adults in the United States (22). However, obese and overweight adults are still twice as likely to have untreated dyslipidemia, highlighting an area that could benefit from increased screening and treatment.
Smoking was the one risk factor where the prevalence has not changed significantly in any BMI group from 1999-2002 to 2007-2010. For this study, we used both self-report of smoking status and serum cotinine levels to estimate smoking exposure. Serum cotinine levels are highly correlated with self-report (23). The lower levels of smoking exposure among overweight and obese adults may indicate a success of smoking prevention or treatment programs among these groups. Reverse causality may also explain this relationship as studies have found smoking to be associated with weight loss and smoking cessation to be associated with weight gain (24). It is also plausible that the self-report data are more susceptible to social desirability bias. However, inclusion of serum cotinine levels reduces this possible bias.
In the United States, over 46% of all adults have at least one uncontrolled risk factor for CVD (25). We found that over 70% of adults 18 years and older had at least one CVD risk factor, either treated or untreated. Our findings further highlight the fact that among obese adults, almost 14% have 3 or more risk factors for CVD and that this percent has increased in the past decade. Each of these CVD risk factors also contributes to increase in disability and morbidity (26). In a recent worldwide report, high BP and tobacco exposure were the top two risk factors attributable to disease and disability. High BMI and elevated glucose levels were numbers 6 and 7 and dyslipidemia was number 15 (26).
Multiple comorbidities are an increasing issue in health care especially among the over 65-year old population (27,28). Among an inpatient sample of adults in the United States, higher costs were associated with three or more chronic conditions (29). Recent commentaries have debated the best method for treatment of multiple chronic conditions (30). Our results inform the debate by further highlighting the high prevalence of multiple CVD risk factors and percent that are undiagnosed, particularly among the obese population.
In recent years, declines in CVD mortality in the United States have been documented. Many of these declines are likely due to improvements in cardiovascular risk factors in the US population (31-35). Among adults with diabetes in the United States, there were significant declines in A1c levels, BP, and low-density cholesterol from 1999 to 2008 (31). A study comparing a cohort from Minnesota to the general US population found that lower levels of CVD risk factors partially explained lower risk of cardiovascular and heart disease mortality observed in the Minnesota cohort (36). Prevention and reduction of cardiovascular risk factors has likely contributed to the decline of cardiovascular mortality in many industrialized countries (37). In the United States, it is estimated that 44% of decline in deaths from coronary disease was due to reductions in risk factors including cholesterol, BP, and smoking (38). These findings, along with the findings reported here, may indicate that physicians and health care providers focus on controlling CVD risk factors among adults who are overweight or obese.
We chose to define untreated diabetes, hypertension, and dyslipidemia based on clinical guidelines and recent evidence of increased levels of risk (10-13). However, these guidelines and recommendations are a moving target. For example, recent guidelines from the Eight Joint National Committee on High Blood Pressure (JNC8) recommend not starting medication for hypertension among adults over 60 years until BP ≥ 150/90 mmHg (39). We did not use this new recommendation in this analysis, because at the time of the surveys the recommendation was for treatment when BP was ≥ 140/90 mmHg (10). Therefore, it is possible that we have overestimated the prevalence of total hypertension and the prevalence of untreated hypertension based on this recent recommendation. Similarly, while the recommendations in the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Cholesterol in Adults (ATP III) focus on total cholesterol with non-HDL cholesterol as a secondary target, recent studies have found non-HDL cholesterol to be an independent predictor of CVD risk (12,40).
The main strength of this study was the use of a nationally representative survey that assessed cardiovascular risk factors in a standardized method over time. The main limitation of this study is that this is only representative of the noninstitutionalized civilian population able to attend the in-person exam. Additionally, NHANES does not allow estimates at the subnational level.
CDC has many programs to address the reduction of cardiovascular risk factors among adults. The National Diabetes Prevention Program is designed to bring evidence-based diabetes prevention for adults at risk for diabetes to communities throughout the United States. (http://www.cdc.gov/diabetes/prevention/about.htm) CDC also has prevention efforts to prevent 1 million heart attacks and strokes over the next 5 years through the Million Hearts campaign (http://www.cdc.gov/features/millionhearts/index.html) and includes goals to reduce hypertension (http://www.cdc.gov/bloodpressure/), cholesterol levels (http://www.cdc.gov/cholesterol/) and tobacco use (http://www.cdc.gov/tobacco/). Despite the improvements in CVD risk factors, obese adults have a two-fold risk compared to normal weight adults for many cardiovascular risk factors. These results highlight the importance of national prevention efforts for obesity, diabetes, hypertension, lipids, and smoking and the progress to date toward these prevention efforts.
Abstract
Objective
To assess whether trends in cardiovascular disease (CVD) risk factors by among overweight and obese US adults have improved.
Methods
The study included 10,568 adults 18 years and older who participated in National Health and Nutrition Examination Survey 1999-2010. CVD risk factors included diabetes (self-reported diagnosis, glycated hemoglobin ≥6.5%, or fasting plasma glucose ≥126mg/dl), hypertension (treatment or blood pressure ≥140/90 mmHg), dyslipidemia (treatment or non-HDL cholesterol ≥160 mg/dl), and smoking (self-report or cotinine levels ≥10 ng/ml). The prevalence and temporal trends of CVD risk factors for each BMI group were estimated.
Results
In 2007-2010, the prevalence of diabetes, hypertension, and dyslipidemia was highest among obese (18.5%, 35.7%, 49.7%, respectively) followed by overweight (8.2%, 26.4%, 44.2%, respectively) and normal weight adults (5.4%, 19.8%, 28.6%, respectively). Smoking exposure was highest among normal weight (29.8%) followed by overweight (24.8%) and obese adults (24.6%). From 1999-2002 to 2007-2010, untreated hypertension decreased among obese and overweight adults and untreated dyslipidemia decreased for all weight groups. There were no significant temporal changes in smoking across BMI groups.
Conclusions
Despite decreases in untreated risk factors, it is important to improve the CVD risk profile of overweight and obese US adults.
Footnotes
Disclosure: S.S., K.M.B., Y.C., L.G., M.A., E.W.G, G.I. have no conflicts of interest to declare.
Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
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