Abnormal Lipid Levels, Diagnosed High Cholesterol, and Lipid-lowering Treatment Among Adults: Los Angeles County and the United States, 1999–2014

by Craig M. Hales, M.D., M.P.H., and Margaret D. Carroll, M.S.P.H., Division of Health and Nutrition Examination Surveys

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The National Health and Nutrition Examination Survey (NHANES), conducted by the National Center for Health Statistics, is a multistage probability sample of the civilian noninstitutionalized population of the United States. A household interview and a physical examination are conducted for each survey participant. Because of the size and population density of Los Angeles (LA) County and the large Mexican-American and Hispanic populations, a primary sampling unit in LA County was chosen with certainty in each 2-year NHANES cycle (1). By aggregating NHANES data between 1999–2006 and 2007–2014 to increase the sample size and improve the reliability of LA County estimates, the prevalence of many health conditions for the LA County and U.S. populations can be estimated and compared.

This Health E-Stat presents the percentage of adults aged 20 and over with high total cholesterol (greater than or equal to 240 mg/dL), low high-density lipoprotein cholesterol (HDL-C) (less than 40 mg/dL), high non-HDL-C (total cholesterol minus HDL-C, greater than or equal to 190 mg/dL), high low-density lipoprotein cholesterol (LDL-C) (greater than or equal to 160 mg/dL), and high triglycerides (greater than or equal to 175 mg/dL). The percentage of adults diagnosed with high cholesterol and, among those with diagnosed high cholesterol, those taking lipid-lowering medications and statins among adults in LA County and the United States during 1999–2006 and 2007–2014 are also presented.

Table 1 shows crude and age-adjusted percentages of adults aged 20 and over with high total cholesterol, low HDL-C, high non-HDL-C, high LDL-C, diagnosed high cholesterol, the percentage taking a lipid-lowering medication among adults diagnosed with high cholesterol, and percentage taking a statin among adults diagnosed with high cholesterol in LA County and the United States for 1999–2006 and 2007–2014 (low HDL-C and high non-HDL-C is shown for 2007–2014 only due to changes in laboratories and methods).

The age-adjusted prevalence of high total cholesterol in LA County was 14.2% in 1999–2006 and 13.8% in 2007–2014, while the prevalence in the United States was 16.8% and 12.8%, respectively. Among adults diagnosed with high cholesterol in LA County, 39.5% took a lipid- lowering medication in 1999–2006 and 38.0% did in 2007–2014 (age-adjusted), while among U.S. adults, 37.3% took a lipid-lowering medication in 1999–2006 and 45.1% did in 2007–2014 (age-adjusted).

Table 2 shows age-adjusted percentages of adults aged 20 and over with high total cholesterol, low HDL-C, high non-HDL-C, high LDL-C, diagnosed high cholesterol, the percentage taking a lipid-lowering medication among adults diagnosed with high cholesterol, and the percentage taking a statin among adults diagnosed with high cholesterol in LA County and the United States by age, sex, and race and Hispanic origin during 2007–2014.

Data source and methods

During the physical examination, venous blood samples were collected from NHANES participants and processed using a standardized protocol. Confidence intervals were constructed using the method of Korn and Graubard and the reliability of estimates was assessed using the NCHS data presentation standards for proportions (2). Despite aggregating NHANES data between 1999–2006 and 2007–2014 to increase the sample size and improve the reliability of LA County estimates, reduced power limited the ability to calculate reliable estimates for health conditions with a low prevalence, especially among subgroups. See the publication “National Health and Nutrition Examination Survey: California and LA County, Estimation Methods and Analytic Considerations” (1) for additional information on methods related to the LA County sample.

References

1. Parker JD, Kruszon-Moran D, Mohadjer LK, Dohrmann SM, Van de Kerckhove W, Clark J, et al. National Health and Nutrition Examination Survey: California and Los Angeles County, estimation methods and analytic considerations, 1999–2006 and 2007–2014. National Center for Health Statistics. Vital Health Stat 2(173). 2017.
2. Parker JD, Talih M, Malec DJ, Beresovsky V, Carroll M, Gonzalez Jr JF. National Center for Health Statistics data presentation standards for proportions. National Center for Health Statistics. Vital Health Stat 2(175). 2017.

Suggested citation

Hales CM, Carroll MD. Abnormal lipid levels, diagnosed high cholesterol, and lipid-lowering treatment among adults: Los Angeles County and the United States, 1999–2014. NCHS Health E-Stat. 2020.

Table

Table 1. Crude and age-adjusted percentage of adults aged 20 and over with abnormal lipids, diagnosed high cholesterol, and taking lipid-lowering medications: Los Angeles County and the United States, 1999–2006 and 2007–2014

…Category not applicable. Percentages prior to 2007–2008 are not presented due to changes in laboratories and methods.
¹Age-adjusted by the direct method to the projected 2000 U.S. census population using the age groups 20–39, 40–59, and 60 and over.

NOTES: CI is confidence interval. HDL-C is high-density lipoprotein cholesterol. LDL-C is low-density lipoprotein cholesterol. Diagnosed high cholesterol is based on an affirmative response to the question, “Have you ever been told by a doctor or other health professional that your blood cholesterol level was high?” Taking a lipid-lowering medication is based on an affirmative response to the question, “Are you currently taking lipid- lowering medication?” asked of adults diagnosed with high cholesterol. Taking a statin is based on a comprehensive enumeration of prescription medications that the participant reported taking in the past 30 days.

SOURCE: National Center for Health Statistics, National Health and Nutrition Examination Survey, 1999–2014.

Table 2. Age-adjusted percentage of adults aged 20 and older with abnormal lipids, diagnosed high cholesterol, and percentage taking lipid-lowering medications by age, sex, and race and Hispanic origin: Los Angeles County and United States, 2007–2014

*Estimate does not meet National Center for Health Statistics standards of reliability.
^†Standard error based on less than 8 degrees of freedom.
‡ Estimate suppressed due to small sample size.
¹Hispanic includes Mexican Americans.

NOTES: CI is confidence interval. HDL-C is high-density lipoprotein cholesterol. LDL-C is low-density lipoprotein cholesterol. Estimates were age-adjusted by the direct method to the projected 2000 U.S. census population using the age groups 20–39, 40–59, and 60 and over. Race and Hispanic origin-specific estimates reflect persons reporting only one race; those reporting more than one race are included in the total but are not reported separately. Diagnosed high cholesterol is based on an affirmative response to the question, “Have you ever been told by a doctor or other health professional that your blood cholesterol level was high?” Taking a lipid-lowering medication is based on an affirmative response to the question, “Are you currently taking lipid-lowering medication?” asked of adults diagnosed with high cholesterol. Taking a statin is based on a comprehensive enumeration of prescription medications that the participant reported taking in the past 30 days.
SOURCE: National Center for Health Statistics, National Health and Nutrition Examination Survey, 2007–2014.