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.

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.

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.

Trends in antihypertensive medication use and blood pressure control among United States adults with hypertension: the National Health And Nutrition Examination Survey, 2001 to 2010.

BACKGROUND: The monitoring of national trends in hypertension treatment and control can provide important insight into the effectiveness of primary prevention efforts for cardiovascular disease. The objective of this study was to examine recent trends in antihypertensive medication use and its impact on blood pressure control among US adults with hypertension. METHODS AND RESULTS: A total of 9320 hypertensive people aged ≥18 years from the National Health and Nutrition Examination Survey 2001 to 2010 were included in this study. The prevalence of antihypertensive medication use increased from 63.5% in 2001 to 2002 to 77.3% in 2009 to 2010 (P(trend)<0.01). Most notably, there was a large increase in the use of multiple antihypertensive agents (from 36.8% to 47.7%, P(trend)<0.01). Overall, the use of thiazide diuretics, ß-blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers increased by 23%, 57%, 31%, and 100%, respectively. In comparison with monotherapy, single-pill combinations and multiple-pill combinations were associated with 55% and 26% increased likelihoods of blood pressure control, respectively. By the 2009 to 2010 time period, 47% of all hypertensive people and 60% of treated hypertensive people had blood pressure controlled. However, higher treated but uncontrolled hypertension rates continued to persist among older Americans, non-Hispanic blacks, diabetic people, and those with chronic kidney disease. Also, Mexican Americans with hypertension were still less likely to take antihypertensive medication than non-Hispanic whites with hypertension. CONCLUSIONS: Antihypertensive medication use and blood pressure control among US adults with hypertension significantly increased over the past 10 years. Combination therapy regimens can facilitate achievement of blood pressure goals.

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.

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.

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.

Multiple imputation of missing dual-energy X-ray absorptiometry data in the National Health and Nutrition Examination Survey.

In 1999, dual-energy x-ray absorptiometry (DXA) scans were added to the National Health and Nutrition Examination Survey (NHANES) to provide information on soft tissue composition and bone mineral content. However, in 1999-2004, DXA data were missing in whole or in part for about 21 per cent of the NHANES participants eligible for the DXA examination; and the missingness is associated with important characteristics such as body mass index and age. To handle this missing-data problem, multiple imputation of the missing DXA data was performed. Several features made the project interesting and challenging statistically, including the relationship between missingness on the DXA measures and the values of other variables; the highly multivariate nature of the variables being imputed; the need to transform the DXA variables during the imputation process; the desire to use a large number of non-DXA predictors, many of which had small amounts of missing data themselves, in the imputation models; the use of lower bounds in the imputation procedure; and relationships between the DXA variables and other variables, which helped both in creating and evaluating the imputations. This paper describes the imputation models, methods, and evaluations for this publicly available data resource and demonstrates properties of the imputations via examples of analyses of the data. The analyses suggest that imputation helps to correct biases that occur in estimates based on the data without imputation, and that it helps to increase the precision of estimates as well. Moreover, multiple imputation usually yields larger estimated standard errors than those obtained with single imputation.

Cardiorespiratory fitness levels among US adults 20-49 years of age: findings from the 1999-2004 National Health and Nutrition Examination Survey.

Data from the 1999-2004 National Health and Nutrition Examination Survey were used to describe the distribution of cardiorespiratory fitness and its association with obesity and leisure-time physical activity (LTPA) for adults 20-49 years of age without physical limitations or indications of cardiovascular disease. A sample of 7,437 adults aged 20-49 years were examined at a mobile examination center. Of 4,860 eligible for a submaximal treadmill test, 3,250 completed the test and were included in the analysis. The mean maximal oxygen uptake ( max) was estimated as 44.5, 42.8, and 42.2 mL/kg/minute for men 20-29, 30-39, and 40-49 years of age, respectively. For women, it was 36.5, 35.4, and 34.4 mL/kg/minute for the corresponding age groups. Non-Hispanic black women had lower fitness levels than did non-Hispanic white and Mexican-American women. Regardless of gender or race/ethnicity, people who were obese had a significantly lower estimated maximal oxygen uptake than did nonobese adults. Furthermore, a positive association between fitness level and LTPA participation was observed for both men and women. These results can be used to track future population assessments and to evaluate interventions. The differences in fitness status among population subgroups and by obesity status or LTPA can also be used to develop health policies and targeted educational campaigns.

Three-phase model harmonizes estimates of the maximal suppression of parathyroid hormone by 25-hydroxyvitamin D in persons 65 years of age and older.

The concentration or threshold of 25-hydroxyvitamin D [25(OH)D] needed to maximally suppress intact serum parathyroid hormone (iPTH) has been suggested as a measure of optimal vitamin D status. Depending upon the definition of maximal suppression of iPTH and the 2-phase regression approach used, 2 distinct clusters for a single 25(OH)D threshold have been reported: 16-20 ng/mL (40-50 nmol/L) and 30-32 ng/mL (75-80 nmol/L). To rationalize the apparently disparate published results, we compared thresholds from several regression models including a 3-phase one to estimate simultaneously 2 thresholds before and after adjusting for possible confounding for age, BMI, glomerular filtration rate, dietary calcium, and season (April-September vs. October-March) within a single data set, i.e. data from the Tufts University Sites Testing Osteoporosis Prevention/Intervention Treatment study, consisting of 181 men and 206 women (total n = 387) ages 65-87 y. Plasma 25(OH)D and serum iPTH concentrations were (mean +/- SD) 22.1 +/- 7.44 ng/mL (55.25 +/- 18.6 nmol/L) and 36.6 +/- 16.03 pg/mL (3.88 +/- 1.7 pmol/L), respectively. The 3-phase model identified 2 thresholds of 12 ng/mL (30 nmol/L) and 28 ng/mL (70 nmol/L); similar results were found from the 2-phase models evaluated, i.e. 13-20 and 27-30 ng/mL (32.5-50 and 67.5-75 nmol/L) and with previous results. Adjusting for confounding did not change the results substantially. Accordingly, the 3-phase model appears to be superior to the 2-phase approach, because it simultaneously estimates the 2 threshold clusters found from the 2-phase approaches along with estimating confidence limits. If replicated, it may be of both clinical and public health importance.

High blood pressure and cardiovascular disease mortality risk among U.S. adults: the third National Health and Nutrition Examination Survey mortality follow-up study.

PURPOSE: We sought to examine whether prehypertension is associated with increased cardiovascular disease (CVD) mortality risk and whether the association of blood pressure with CVD outcome is modified by social demographics or hypertension treatment and control. METHODS: Data from the Third National Health and Nutrition Examination Survey and mortality follow-up through 2000 were used to estimate the relative risk of death from CVD associated with hypertension and prehypertension, after adjusting for confounding and modifying factors. RESULTS: Compared with normotension, the relative risks of CVD mortality were 1.23 (95% confidence interval [95% CI] 0.85-1.79, p=0.26) for prehypertension, 1.64 (95% CI 1.11-2.41, p=0.01) for hypertension, 1.74 (95% CI 1.28-2.49, p=0.007) for uncontrolled hypertension, and 1.15 (95% CI 0.79-1.80, p=0.53) for controlled hypertension. Hypertensive adults <65 years and non-Hispanic blacks had a 3.86-fold and a 4.65-fold increased CVD mortality risk respectively. Age, gender, and race/ethnicity stratified analyses showed no associations between prehypertension and CVD mortality. However, blood pressure at a high range of prehypertension (130-139/84-89 mmHg) was associated with increased risk of CVD mortality (hazard ratio 1.41, p<0.05) relative to blood pressure less than 120/80 mmHg. CONCLUSIONS: This study supports a strong, significant, and independent association of elevated blood pressure with CVD mortality risk. Hypertension continued to greatly increase CVD morality risk, particularly among persons <65 years and non-Hispanic blacks. Treatment and control of hypertension eliminated the excess CVD mortality risk observed among the hypertension population.

Gender differences in hypertension treatment, drug utilization patterns, and blood pressure control among US adults with hypertension: data from the National Health and Nutrition Examination Survey 1999-2004.

BACKGROUND: National guidelines recommend the same approach for treating hypertensive men and women. It is not known, however, whether current US antihypertensive medication utilization patterns and the resulting degrees of blood pressure (BP) control are similar or different among hypertensive women and men. METHODS: The study was a cross-sectional, nationally representative survey of the noninstitutionalized civilian US population. Persons aged > or =18 years from the National Health and Nutrition Examination Survey (NHANES) 1999-2004 were classified as hypertensive based on a BP > or =140/90 mm Hg, currently taking antihypertensive medication, or having been diagnosed by a physician. RESULTS: Among hypertensives, the prevalence of antihypertensive medication use was significantly higher among women than men (61.4% vs. 56.8%), especially among middle-aged persons (40-49 years, 53.1% vs. 42.7%) and among non-Hispanic blacks (65.5% vs. 54.6%). Also, treated women were more likely than men to use diuretics (31.6% vs. 22.3%) and angiotensin receptor blockers (11.3% vs. 8.7%). Among treated hypertensives, the proportion taking three or more antihypertensive drugs was lower among women than men, especially among older persons (60-69 years: 12.3% vs. 19.8%, 70-79 years: 18.6% vs. 21.2%, and > or =80 years: 18.8% vs. 22.8%). Only 44.8% of treated women achieved BP control vs. 51.1% of treated men. CONCLUSIONS: Hypertensive women are significantly more likely to be treated than men, but less likely to have achieved BP control. Additional efforts may be needed to achieve therapeutic goals for the US hypertensive population, especially for hypertensive women.

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.

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.

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.

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.

Prescription drug use continues to increase: U.S. prescription drug data for 2007-2008.

KEY FINDINGS: Over the last 10 years, the percentage of Americans who took at least one prescription drug in the past month increased from 44% to 48%. The use of two or more drugs increased from 25% to 31%. The use of five or more drugs increased from 6% to 11%. In 2007-2008, 1 out of every 5 children and 9 out of 10 older Americans reported using at least one prescription drug in the past month. Those who were without a regular place for health care, health insurance, or prescription drug benefit had less prescription drug use compared with those who had these benefits. The most commonly used types of drugs included: asthma medicines for children, central nervous system stimulants for adolescents, antidepressants for middle-aged adults, and cholesterol lowering drugs for older Americans.