National Health and Nutrition Examination Survey: Estimation Procedures, 2011-2014.

This report describes the methods used to create NHANES 2011-2014 sample weights and variance units for the public-use data files, including sample weights for selected subsamples, such as the fasting subsample. The impacts of sample design changes on estimation for NHANES 2011-2014 and the addition of the NHANES National Youth Fitness Survey (NNYFS) 2012 are described. Approaches that data users can employ to modify sample weights when combining survey cycles or when combining subsamples are also included.

National Health and Nutrition Examination Survey: California and Los Angeles County, Estimation Methods and Analytic Considerations, 1999-2006 and 2007-2014.

Background California is the most populated state and Los Angeles County is the most populated county in the United States. National Health and Nutrition Examination Survey (NHANES) sample weights and variance units were developed for these places to obtain subnational estimates. Objective This report describes the California and Los Angeles County NHANES 1999-2006 and 2007-2014 samples, including the creation of the sample weights and variance units and descriptions of the resulting data files. Some analytic guidelines are provided. Results Eight years of NHANES data were combined for each data file to provide an adequate sample size and reduce disclosure risks. Because Los Angeles County has been a self-representing primary sampling unit, sample weights for Los Angeles County were relatively straightforward. However, a modelbased approach was used to create sample weights for California. The relatively large proportion of Mexican- American and other Hispanic persons in California, coupled with the different NHANES 1999-2014 sample design requirements for oversampling these groups within the small number of NHANES locations selected each cycle, led to a relatively large size of these groups in the California and Los Angeles County NHANES files. For example, 1,137 and 374 of the 3,353 Mexican-Americans persons in NHANES 2007-2014 were in the California and Los Angeles County samples, respectively. Conclusion The California and Los Angeles County NHANES 1999-2006 and 2007-2014 samples are available in the National Center for Health Statistics Research Data Center.

Overview of Asian American Data Collection, Release, and Analysis: National Health and Nutrition Examination Survey 2011-2018.

Data System. The National Health and Nutrition Examination Survey (NHANES), conducted by the National Center for Health Statistics, is a cross-sectional survey on the health and nutritional status of US adults and children. Data Collection/Processing. A complex, multistage probability design is used to select a sample representative of the US civilian, noninstitutionalized population. NHANES includes in-home interviews, physical examinations, and biospecimen collection. About 5000 persons are examined annually. Since 2011, NHANES has been oversampling Asian Americans in addition to traditionally oversampled groups, including Hispanics and non-Hispanic Blacks. Data Analysis/Dissemination. Data are publicly released online in 2-year cycles. Some data, because of disclosure risk, are only available through the Research Data Center. Data users should read documentation, examine sample sizes and response rates, and account for the complex survey design. With publicly released data, analyses of Asians as a single group is only possible; some Asian subgroup analyses may be conducted through the Research Data Center. Public Health Implications. Oversampling Asians in NHANES 2011-2018 allows national estimates to be computed on health conditions, nutrition, and risk factors of public health importance on this growing subpopulation of Asian Americans.

Preventive Aspirin and Other Antiplatelet Medication Use Among U.S. Adults Aged ≥ 40 Years: Data from the National Health and Nutrition Examination Survey, 2011-2012.

OBJECTIVE: We estimated the prevalence of preventive aspirin and/or other antiplatelet medication use and the dosage of aspirin use in the U.S. adult population. METHODS: We conducted cross-sectional analyses of a representative sample (n=3,599) of U.S. adults aged ≥ 40 years from the National Health and Nutrition Examination Survey, 2011-2012. RESULTS: In 2011-2012, one-third of U.S. adults aged ≥ 40 years reported taking preventive aspirin and/or other antiplatelet medications, 97% of whom indicated preventive aspirin use. Preventive aspirin use increased with age (from 11% of those aged 40-49 years to 54% of those ≥ 80 years of age, p<0.001). Non-Hispanic white (35%) and black (30%) adults were more likely to take preventive aspirin than non-Hispanic Asian (20%, p<0.001) and Hispanic (22%, p=0.013) adults. Adults with, compared with those without health insurance, and adults with ≥ 2 doctor visits in the past year, diagnosed diabetes, hypertension, or high cholesterol were twice as likely to take preventive aspirin. Among those with cardiovascular disease, 76% reported taking preventive aspirin and/or other antiplatelet medications, of whom 91% were taking preventive aspirin. Among adults without cardiovascular disease, 28% reported taking preventive aspirin. Adherence rates to medically recommended aspirin use were 82% overall, 91% for secondary prevention, and 79% for primary prevention. Among current preventive aspirin users, 70% were taking 81 milligrams (mg) of aspirin daily and 13% were taking 325 mg of aspirin daily. CONCLUSION: The vast majority of antiplatelet therapy is preventive aspirin use. A health-care provider's recommendation to take preventive aspirin is an important determinant of current preventive aspirin use.

Trends in blood pressure among adults with hypertension: United States, 2003 to 2012.

The aim of this study is to describe trends in the awareness, treatment, and control of hypertension; mean blood pressure; and the classification of blood pressure among US adults 2003 to 2012. Using data from the National Health and Nutrition Examination Survey 2003 to 2012, a total of 9255 adult participants aged ≥18 years were identified as having hypertension, defined as measured blood pressure ≥140/90 mm Hg or taking prescription medication for hypertension. Awareness and treatment among hypertensive adults were ascertained via an interviewer administered questionnaire. Controlled hypertension among hypertensive adults was defined as systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg. Blood pressure was categorized as optimal blood pressure, prehypertension, and stage I and stage II hypertension. Between 2003 and 2012, the percentage of adults with controlled hypertension increased (P-trend <0.01). Hypertensive adults with optimal blood pressure and with prehypertension increased from 13% to 19% and 27% to 33%, respectively (P-trend <0.01 for both groups). Among hypertensive adults who were taking antihypertensive medication, uncontrolled hypertension decreased from 38% to 30% (P-trend <0.01). Similarly, a decrease in mean systolic blood pressure was observed (P-trend <0.01); however, mean diastolic blood pressure remained unchanged. The trend in the control of blood pressure has improved among hypertensive adults resulting in a higher percentage with blood pressure at the optimal or prehypertension level and a lower percentage in stage I and stage II hypertension. Overall, mean systolic blood pressure decreased as did the prevalence of uncontrolled hypertension among the treated hypertensive population.

Prescription cholesterol-lowering medication use in adults aged 40 and over: United States, 2003-2012.

During 2003­2012, there was a significant increase in the percentage of adults aged 40 and over who used a prescription cholesterol-lowering medication. In 2003­2004, one in five adults reported using a prescription cholesterol-lowering medication in the past 30 days. By 2011­2012, that number had risen to one in four adults. In 2011­2012, the majority of adults using a cholesterol-lowering medication reported using a statin alone (83%). Ten percent used both a statin and a nonstatin and another 7% used only a nonstatin. Simvastatin was the most commonly used medication, with 42% of all cholesterol-lowering medication users reporting its use, followed by atorvastatin (20.2%). Use of a prescription cholesterol-lowering medication increased with age but was similar between men and women and race and Hispanic origin groups. Adults aged 40­64 who reported having health insurance or prescription medication coverage were more likely to take prescription cholesterol-lowering medications. Hypercholesterolemia or high cholesterol is one of the most common preventable risk factors for atherosclerotic CVD. In 2011­2012, more than 30 million Americans aged 20 and over (13%) had measured high total cholesterol (5). There is extensive and consistent evidence supporting the use of cholesterol-lowering medication, especially statins, in addition to lifestyle changes, to treat lipid disorders and reduce atherosclerotic CVD events. The 2013 cholesterol treatment guidelines updated recommendations for statin therapy on the basis of low-density lipid cholesterol levels and atherosclerotic CVD risks (6). Approximately 71% of adults with diagnosed CVD, 63% of those with diagnosed diabetes, and 54% of those with diagnosed hypercholesterolemia reported taking prescription cholesterol-lowering medications.

Perception of weight status in U.S. children and adolescents aged 8-15 years, 2005-2012.

Childhood obesity is a major public health problem associated with many adverse health outcomes in adulthood (1). During 2011­2012, nearly 17% of children and adolescents were obese (2). Weight status misperception occurs when the child's perception of their weight status differs from their actual weight status based on measured height and weight. Accurate weight status self-perception has been linked to appropriate weight control behaviors in youth. The National Health and Nutrition Examination Survey (NHANES) data for children and adolescents aged 8­15 years offers an opportunity to examine weight perception status in this age group.

Cardiorespiratory fitness levels among U.S. youth aged 12-15 years: United States, 1999-2004 and 2012.

Data from the National Health and Nutrition Examination Survey (NHANES), 1999-2004 and the NHANES National Youth Fitness Survey, 2012 In 2012, about 42% of U.S. youth aged 12-15 years had adequate levels of cardiorespiratory fitness. The percentage of youth who had adequate levels of cardiorespiratory fitness did not differ by race and Hispanic origin, or by family income-to-poverty ratio. The percentage of youth who had adequate levels of cardiorespiratory fitness decreased as weight status increased. The percentage of youth aged 12-15 who had adequate levels of cardiorespiratory fitness decreased from 52.4% in 1999-2000 to 42.2% in 2012. Physical fitness has been defined as "a set of attributes that people have or achieve that relates to the ability to perform physical activity" (1). Cardiorespiratory fitness is one component of physical fitness and is defined as the "ability of the circulatory and respiratory systems to supply fuel during sustained physical activity and to eliminate fatigue products after supplying fuel" (1). Cardiorespiratory fitness is most often measured by maximal oxygen uptake (VO2max), which is the maximum capacity of the body to transport and use oxygen during physical activity (2). This report presents the most recent national data on the percentage of youth who had adequate levels of cardiorespiratory fitness. Adequate levels of cardiorespiratory fitness are based on standards that are age- and sex-specific and established based on how fit children need to be for good health.

National Health and Nutrition Examination Survey: national youth fitness survey plan, operations, and analysis, 2012.

BACKGROUND: In October 2008, the federal government issued its first-ever Physical Activity Guidelines for Americans to provide science-based guidance on the types and amounts of physical activity that provide substantial health benefits for Americans (1). Guidelines for children and adolescents recommend 60 minutes or more of aerobic, muscle-strengthening, or bone-strengthening physical activity daily (1). While the number of children in the United States who meet the recommendations in the Physical Activity Guidelines is unknown, the percentage that is physically active in the United States may be declining. No recent national data exist on the fitness levels of children and adolescents. The National Health and Nutrition Examination Survey's (NHANES) National Youth Fitness Survey (NNYFS) was conducted in 2012 and collected data on physical activity and fitness levels for U.S. children and adolescents aged 3-15 years. OBJECTIVES: The objective of NNYFS was to provide national-level estimates of the physical activity and fitness levels of children, based on interview and physical examination data. Results from the survey are intended to contribute to the development of policies and programs to improve youth fitness nationally. The data also may be used in the development of national reference standards for measures of fitness and physical activity. Methods The NNYFS survey design used the design for NHANES, which is a multistage probability sample of the civilian noninstitutionalized resident population of the United States. NNYFS consisted of a household interview and a physical activity and fitness examination in a mobile examination center. A total of 1,640 children and adolescents aged 3-15 were interviewed, and 1,576 were examined.

Urine sodium excretion increased slightly among U.S. adults between 1988 and 2010.

Little information is available on temporal trends in sodium intake in the U.S. population using urine sodium excretion as a biomarker. Our aim was to assess 1988-2010 trends in estimated 24-h urine sodium (24hUNa) excretion among U.S. adults (age 20-59 y) participating in the cross-sectional NHANES. We used subsamples from a 1988-1994 convenience sample, a 2003-2006 one-third random sample, and a 2010 one-third random sample to comply with resource constraints. We estimated 24hUNa excretion from measured sodium concentrations in spot urine samples by use of calibration equations (for men and women) derived from the International Cooperative Study on Salt, Other Factors, and Blood Pressure study. Estimated 24hUNa excretion increased over the 20-y period [1988-1994, 2003-2006, and 2010; means ± SEMs (n): 3160 ± 38.4 mg/d (1249), 3290 ± 29.4 mg/d (1235), and 3290 ± 44.4 mg/d (525), respectively; P-trend = 0.022]. We observed significantly higher mean estimated 24hUNa excretion in each survey period (P < 0.001) for men compared with women (31-33%) and for persons with a higher body mass index (BMI; 32-35% for obese vs. normal weight) or blood pressure (17-26% for hypertensive vs. normal blood pressure). After adjusting for age, sex, and race-ethnicity, temporal trends in mean estimated 24hUNa excretion remained significant (P-trend = 0.004). We observed no temporal trends in mean estimated 24hUNa excretion among BMI subgroups, nor after adjusting for BMI. Although several limitations apply to this analysis (the use of a convenience sample in 1988-1994 and using estimated 24hUNa excretion as a biomarker of sodium intake), these first NHANES data suggest that mean estimated 24hUNa excretion increased slightly in U.S. adults over the past 2 decades, and this increase may be explained by a shift in the distribution of BMI.

Physical activity in U.S. youth aged 12-15 years, 2012.

KEY FINDINGS: Data from the combined National Health and Nutrition Examination Survey (NHANES) and the NHANES National Youth Fitness Survey, 2012. In 2012, about one-quarter of U.S. youth aged 12-15 years engaged in moderate-to-vigorous physical activity for at least 60 minutes daily. Basketball was the most common activity reported among active boys, followed by running, football, bike riding, and walking. Running was the most common activity among active girls, followed by walking, basketball, dancing, and bike riding. The percentage of male youth who were physically active for at least 60 minutes daily decreased as weight status increased. The 2008 Physical Activity Guidelines for Americans, which have been adopted by the First Lady's Let's Move! initiative and the American Academy of Pediatrics, recommend that youth participate in daily moderate-to-vigorous physical activity for at least 60 minutes (1-5). This report presents the most recent national data from 2012 on self-reported physical activity among youth aged 12-15 years, by sex and weight status. This report also describes the most common types of physical activities--outside of school-based physical education (PE) or gym classes--in which youth engage.

National health and nutrition examination survey: sample design, 2011-2014.

Background Data collection for the National Health and Nutrition Examination Survey (NHANES) consists of a household screener, an interview, and a physical examination. The screener primarily determines whether any household members are eligible for the interview and examination. Eligibility is established using preset selection probabilities for the desired demographic subdomains. After an eligible sample person is selected, the interview collects person-level demographic, health, and nutrition information, as well as information about the household. The examination includes physical measurements, tests such as hearing and dental examinations, and the collection of blood and urine specimens for laboratory testing. Objectives This report provides some background on the NHANES program, beginning with the first survey cycle in the 1970s and highlighting significant changes since its inception. The report then describes the broad design specifications for the 2011-2014 survey cycle, including survey objectives, domain and precision specifications, and operational requirements unique to NHANES. The report also describes details of the survey design, including the calculation of sampling rates and sample selection methods. Documentation of survey content, data collection procedures, estimation methods, and methods to assess nonsampling errors are reported elsewhere.

National Health and Nutrition Examination Survey: National Youth Fitness Survey Estimation Procedures, 2012.

BACKGROUND: The National Health and Nutrition Examination Survey's (NHANES) National Youth Fitness Survey (NNYFS) was conducted in 2012 by the Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS). NNYFS collected data on physical activity and fitness levels to evaluate the health and fitness of children aged 3-15 in the United States. The survey comprised three levels of data collection: a household screening interview (or screener), an in-home personal interview, and a physical examination. The screener's primary objective was to determine whether any children in the household were eligible for the interview and examination. Eligibility was determined by preset selection probabilities for desired sex-age subdomains. After selection, the in-home personal interview collected demographic, health, physical activity, and nutrition information about the child as well as information about the household. The examination included physical measurements and fitness tests. OBJECTIVES: This report provides background on the NNYFS program and summarizes the survey's sample design specifications. The report presents NNYFS estimation procedures, including the methods used to calculate survey weights for the full sample as well as a combined NHANES/NNYFS sample for 2012 (accessible only through the NCHS Research Data Center). The report also describes appropriate variance estimation methods. Documentation of the sample selection methods, survey content, data collection procedures, and methods to assess nonsampling errors are reported elsewhere.

Hypertension among adults in the United States: National Health and Nutrition Examination Survey, 2011-2012.

The overall prevalence of hypertension has not changed appreciably since 2009-2010. The age-adjusted prevalence of hypertension among U.S. adults was 29.1% in 2011-2012. Among adults with hypertension in 2011-2012, 82.8% were aware of their hypertension, 75.7% were currently taking medication to lower their blood pressure, and 51.9% had their blood pressure controlled to less than 140/90 mm Hg. Men and women had similar prevalence and awareness of hypertension, but more women than men were treating their hypertension and had it under control. Young adults aged 18-39 continued to have lower awareness, treatment, and control of their hypertension compared with older adults. Hypertension prevalence was still highest among non-Hispanic black adults. However, awareness, treatment, and control of hypertension were similar among non-Hispanic black, non-Hispanic white, and Hispanic adults. Non-Hispanic Asian adults had a lower prevalence of awareness than the other race and Hispanic origin groups, and lower treatment than non-Hispanic white and non-Hispanic black adults. However, hypertension control was similar among non-Hispanic Asian adults and the other race and Hispanic origin groups. Hypertension is a common and manageable chronic condition. Based on recent national data from 2011-2012, treatment of hypertension exceeded the Healthy People 2020 target goal of 69.5%. However, the control of hypertension has neither met the goal of the Healthy People 2020 (61.2% by 2020) nor the Million Hearts Initiative (65% by 2017). These results provide evidence for continued efforts to improve the management of hypertension in order to attain these goals.

Urinary excretion of sodium, potassium, and chloride, but not iodine, varies by timing of collection in a 24-hour calibration study.

Because of the logistic complexity, excessive respondent burden, and high cost of conducting 24-h urine collections in a national survey, alternative strategies to monitor sodium intake at the population level need to be evaluated. We conducted a calibration study to assess the ability to characterize sodium intake from timed-spot urine samples calibrated to a 24-h urine collection. In this report, we described the overall design and basic results of the study. Adults aged 18-39 y were recruited to collect urine for a 24-h period, placing each void in a separate container. Four timed-spot specimens (morning, afternoon, evening, and overnight) and the 24-h collection were analyzed for sodium, potassium, chloride, creatinine, and iodine. Of 481 eligible persons, 407 (54% female, 48% black) completed a 24-h urine collection. A subsample (n = 133) collected a second 24-h urine 4-11 d later. Mean sodium excretion was 3.54 ± 1.51 g/d for males and 3.09 ± 1.26 g/d for females. Sensitivity analysis excluding those who did not meet the expected creatinine excretion criterion showed the same results. Day-to-day variability for sodium, potassium, chloride, and iodine was observed among those collecting two 24-h urine samples (CV = 16-29% for 24-h urine samples and 21-41% for timed-spot specimens). Among all race-gender groups, overnight specimens had larger volumes (P < 0.01) and lower sodium (P < 0.01 to P = 0.26), potassium (P < 0.01), and chloride (P < 0.01) concentrations compared with other timed-spot urine samples, although the differences were not always significant. Urine creatinine and iodine concentrations did not differ by the timing of collection. The observed day-to-day and diurnal variations in sodium excretion illustrate the importance of accounting for these factors when developing calibration equations from this study.

Is there a reverse J-shaped association between 25-hydroxyvitamin D and all-cause mortality? Results from the U.S. nationally representative NHANES.

CONTEXT: A reverse J-shaped association between serum 25-hydroxyvitamin D (25[OH]D) concentration and all-cause mortality was suggested in a 9-year follow-up (1991-2000) analysis of the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). OBJECTIVE: Our objective was to repeat the analyses with 6 years additional follow-up to evaluate whether the association persists through 15 years of follow-up. PARTICIPANTS: The study included 15 099 participants aged ≥ 20 years with 3784 deaths. MAIN OUTCOME MEASURE: Relative risk (RR) of death from all causes was adjusted for age, sex, race/ethnicity, and season using 2 Poisson regression approaches: traditional categorical and cubic splines. Results were given for 9 25(OH)D levels: <20, 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 74, 75 to 99 (reference), 100 to 119, and ≥ 120 nmol/L. RESULTS: The reverse J-shaped association became stronger with longer follow-up and was not affected by excluding deaths within the first 3 years of follow-up. Similar results were found from both statistical approaches for levels <20 through 119 nmol/L. Adjusted RR (95% confidence interval [CI]) estimates for all levels <60 nmol/L were significantly >1 compared with the reference group. The nadir of risk was 81 nmol/L (95% CI, 73-90 nmol/L). For 25(OH)D ≥ 120 nmol/L, results (RR, 95% CI) were slightly different using traditional categorical (1.5, 1.02-2.3) and cubic splines approaches (1.2, 0.9-1.4). The association appeared in men, women, adults ages 20 to 64 years, and non-Hispanic whites but was weaker in older adults. The study was too small to evaluate the association in non-Hispanic black and Mexican-American adults. CONCLUSIONS: A reverse J-shaped association between serum 25(OH)D and all-cause mortality appears to be real. It is uncertain whether the association is causal.

National Health and Nutrition Examination Survey: sample design, 2007-2010.

BACKGROUND: Data collection for the National Health and Nutrition Examination Survey (NHANES) comprises three levels: a household screener, an interview, and a physical examination. The primary objective of the screener is to determine whether any household members are eligible for the interview an dexamination. Eligibility is determined by preset selection probabilities for the desired demographic subdomains. After an eligible sample person is selected, the interview collects person-level demographic, health, and nutrition information, as well as information about the household. The examination includes physical measurements, tests such as hearing and dental examinations, and the collection of blood and urine specimens for laboratory testing. OBJECTIVES: This report provides some background on the NHANES program, beginning with the first survey cycle in the 1970s and highlighting significant changes since its inception. The report then describes the broad design specifications for the 2007-2010 survey cycle, including survey objectives, domain and precision specifications, and operational requirements unique to NHANES. In addition, the report describes the details of the survey design, including the calculation of sampling rates and sample selection methods. Documentation of survey content, data collection procedures, estimation methods, and methods to assess nonsampling errors are reported elsewhere.

National Health and Nutrition Examination Survey: estimation procedures, 2007-2010.

BACKGROUND: Data collection for the National Health and Nutrition Examination Survey (NHANES), comprises three levels: an initial household screening interview (or ''screener''), an in-home personal interview, and a physical examination. The primary objective of the screener is to determine whether any household members are eligible for the interview and examination. Eligibility is determined by preset selection probabilities for the desired demographic subdomains. After an eligible sample person is selected, the in-home interview collects person-level demographic, health, and nutrition information, as well as information about the household. The examination includes physical measurements such as blood pressure, a dental examination, and the collection of blood and urine specimens for laboratory testing. OBJECTIVES: This report provides background for the NHANES program and summarizes the sample design specifications for the 2007-2010 survey cycle. Estimation procedures are then presented, including the methods used to calculate survey weights for the full sample and for examination subsamples, as well as guidelines for combining 2-year weights for the analysis of multiyear data. Finally, the appropriate variance estimation methods are described. The sample selection methods, survey content, data collection procedures, and methods for assessing nonsampling errors are documented elsewhere.

Hypertension among adults in the United States, 2009-2010.

Significant increases have been seen over the past 10 years in hypertension awareness, treatment, and control among adults with hypertension. However, less than 50% of adults with hypertension controlled their blood pressure (BP) in 2007­2008 (1). The high prevalence of undiagnosed and uncontrolled hypertension, especially among minority groups, remains a challenge (2,3). A recent prediction model showed that every 10% increase in hypertension treatment could prevent an additional 14,000 deaths per year in the adult population ages 25­79 (4). This report examines the most recent national data on hypertension prevalence, awareness, treatment, and control.