Assessing Laboratory Method Validations for Informing Inference Across Survey Cycles in the National Health and Nutrition Examination Survey.

Background and objectives Laboratory tests conducted on survey respondents' biological specimens are a major component of the National Health and Nutrition Examination Survey. The National Center for Health Statistics' Division of Health and Nutrition Examination Surveys performs internal analytic method validation studies whenever laboratories undergo instrumental or methodological changes, or when contract laboratories change. These studies assess agreement between methods to evaluate how methodological changes could affect data inference or compromise consistency of measurements across survey cycles.

National Health and Nutrition Examination Survey, 2017-March 2020 Prepandemic File: Sample Design, Estimation, and Analytic Guidelines.

Objectives This report describes the creation of the NHANES 2017-March 2020 prepandemic data files, including the selection of the appropriate NHANES sample design (2015-2018) to create sample weights and variance units for public-use data files. Additionally, the development of a factor applied to the primary sampling units to adjust the 2017-March 2020 data to fit the NHANES 2015-2018 sample design is described. Analyses to assess representativeness of the target population were performed, and a simulation to replicate the impact of interrupted data collection using earlier NHANES cycles was undertaken.

Differences in Hypertension and Stage II Hypertension by Demographic and Risk Factors, Obtained by Two Different Protocols in US Adults: National Health and Nutrition Examination Survey, 2017-2018.

Background: To compare prevalence of hypertension and stage II hypertension assessed by 2 blood pressure (BP) observation protocols.

Methods: Participants aged 18 years and older (n = 4,689) in the National Health and Nutrition Examination Survey (NHANES 2017-2018) had their BP measured following 2 protocols: the legacy auscultation protocol (AP) and oscillometric protocol (OP). The order of protocols was randomly assigned.

National Health and Nutrition Examination Survey 2017-March 2020 Prepandemic Data Files-Development of Files and Prevalence Estimates for Selected Health Outcomes.

Background And Objectives: In March 2020, the coronavirus disease 2019 (COVID-19) pandemic halted National Health and Nutrition Examination Survey (NHANES) field operations. As data collected in the partial 2019-2020 cycle (herein referred to as 2019-March 2020) are not nationally representative, they were combined with previously released 2017-2018 data to produce nationally representative estimates. This report explains the creation of the 2017-March 2020 prepandemic data files, provides recommendations for and limitations of the files' use, and presents prevalence estimates for selected health outcomes based on the files.

National Health and Nutrition Examination Survey, 2015-2018: Sample Design and Estimation Procedures.

Background The purpose of the National Health and Nutrition Examination Survey (NHANES) is to produce national estimates representative of the total noninstitutionalized civilian U.S. population.

An Investigation of Nonresponse Bias and Survey Location Variability in the 2017-2018 National Health and Nutrition Examination Survey.

Over the past two decades, a steady decline in response rates on national face-to-face surveys has been documented, with steeper declines observed in recent years. The impact of nonresponse on survey estimates is inconsistent and depends on the correlation between response propensity and the survey estimates. To better understand the impact of declining response rates on the 2017-2018 National Health and Nutrition Examination Survey (NHANES), potential nonresponse bias (NRB) was investigated.

Association of usual 24-h sodium excretion with measures of adiposity among adults in the United States: NHANES, 2014.

Background: Both excessive sodium intake and obesity are risk factors for hypertension and cardiovascular disease. The association between sodium intake and obesity is unclear, with few studies assessing sodium intake using 24-h urine collection.

Objectives: Our objective was to assess the association between usual 24-h sodium excretion and measures of adiposity among US adults.

Prevalence of Total, Diagnosed, and Undiagnosed Diabetes Among Adults: United States, 2013-2016.

Diabetes is a major cause of morbidity and mortality in the United States (1-3). Diabetes can be present but undiagnosed, meaning that a person can have diabetes but not report having ever been told by a doctor or health professional that they have the condition. Type 2 diabetes can progress over an extended time period with gradual, often unnoticed, changes occurring before diagnosis.

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.

Estimated 24-Hour Urinary Sodium and Potassium Excretion in US Adults.

Importance: In 2010, the Institute of Medicine (now the National Academy of Medicine) recommended collecting 24-hour urine to estimate US sodium intake because previous studies indicated 90% of sodium consumed was excreted in urine.

Objective: To estimate mean population sodium intake and describe urinary potassium excretion among US adults.

Design, Setting, And Participants: In a nationally representative cross-sectional survey of the US noninstitutionalized population, 827 of 1103 (75%) randomly selected, nonpregnant participants aged 20 to 69 years in the examination component of the National Health and Nutrition Examination Survey (NHANES) collected at least one 24-hour urine specimen in 2014.

Association Between Urinary Sodium and Potassium Excretion and Blood Pressure Among Adults in the United States: National Health and Nutrition Examination Survey, 2014.

Background: Higher levels of sodium and lower levels of potassium intake are associated with higher blood pressure. However, the shape and magnitude of these associations can vary by study participant characteristics or intake assessment method. Twenty-four-hour urinary excretion of sodium and potassium are unaffected by recall errors and represent all sources of intake, and were collected for the first time in a nationally representative US survey.

Comparison of blood pressure measurements obtained in the home setting: analysis of the Health Measures at Home Study.

Background: Automated blood pressure (BP) devices have been used in the home for self-management purposes and are increasingly being used in population-based research. Although these devices are convenient and affordable and may be used by inexperienced lay personnel, the potential impact of an examiner's skill level on the results needs to be evaluated quantitatively. The aim of this study was to compare BP measurements obtained in a home setting by personnel with healthcare experience with those obtained by personnel without healthcare experience.

Feasibility of collecting 24-h urine to monitor sodium intake in the National Health and Nutrition Examination Survey.

Background: Twenty-four-hour urine sodium excretion is recommended for monitoring population sodium intake. Because of concerns about participation and completion, sodium excretion has not been collected previously in US nationally representative surveys.

Objective: We assessed the feasibility of implementing 24-h urine collections as part of a nationally representative survey.

Estimating the population distribution of usual 24-hour sodium excretion from timed urine void specimens using a statistical approach accounting for correlated measurement errors.

Background: High US sodium intake and national reduction efforts necessitate developing a feasible and valid monitoring method across the distribution of low-to-high sodium intake.

Objective: We examined a statistical approach using timed urine voids to estimate the population distribution of usual 24-h sodium excretion.

Methods: A sample of 407 adults, aged 18-39 y (54% female, 48% black), collected each void in a separate container for 24 h; 133 repeated the procedure 4-11 d later.

Collection and laboratory methods for dried blood spots for hemoglobin A1c and total and high-density lipoprotein cholesterol in population-based surveys.

Background: The Health Measures at Home Study was a study designed to evaluate the feasibility of incorporating dried blood spots (DBS) collection into the National Health Interview Survey and to compare the proficiencies between field interviewers and health technicians in obtaining DBS.

Methods: DBS collection and venipuncture were attempted on 125 participants. The DBS were collected in the participant's home and venous blood was collected in the National Health and Nutrition Examination Survey (NHANES) mobile examination center.

Comparison of population iodine estimates from 24-hour urine and timed-spot urine samples.

Background: Median urine iodine concentration (UIC; μg/L) in spot urine samples is recommended for monitoring population iodine status. Other common measures are iodine:creatinine ratio (I/Cr; μg/g) and estimated 24-hour urine iodine excretion (UIE; I/Cr × predicted 24-hour Cr; μg/day). Despite different units, these measures are often used interchangeably, and it is unclear how they compare with the reference standard 24-hour UIE.

Validity of predictive equations for 24-h urinary sodium excretion in adults aged 18-39 y.

Background: Collecting a 24-h urine sample is recommended for monitoring the mean population sodium intake, but implementation can be difficult.

Objective: The objective was to assess the validity of published equations by using spot urinary sodium concentrations to predict 24-h sodium excretion.

Design: This was a cross-sectional study, conducted from June to August 2011 in metropolitan Washington, DC, of 407 adults aged 18-39 y, 48% black, who collected each urine void in a separate container for 24 h.

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.

Home blood pressure monitoring and hypertension status among US adults: the National Health and Nutrition Examination Survey (NHANES), 2009-2010.

Background: Currently, no national prevalence is available on home blood pressure monitoring (HBPM).

Methods: This report is based on national-level, cross-sectional data for noninstitutionalized US adults aged ≥18 years (n = 6,001 participants) from the National Health and Nutrition Examination Survey (NHANES), 2009-2010.

Results: Overall, 21.

Comparison of dried blood spot to venous methods for hemoglobin A1c, glucose, total cholesterol, high-density lipoprotein cholesterol, and C-reactive protein.

Background: Compared to venipuncture, dried blood spots (DBS) can be collected by non-phlebotomists in non-clinical settings, is relatively inexpensive, more easily transported and stored conveniently. Disadvantages of DBS include difficult assay development and validation. This study compared DBS to venous methods for hemoglobin A1c, glucose, total cholesterol, high-density lipoprotein cholesterol, and C-reactive protein (CRP).

Prevalence of uncontrolled risk factors for cardiovascular disease: United States, 1999-2010.

Heart disease is the leading cause of death in the United States (1). High blood pressure, high cholesterol, and smoking are all risk factors that could lead to cardiovascular disease (CVD) and stroke. The recently announced Million Hearts Initiative is aimed at preventing 1 million heart attacks and strokes over the next 5 years (2–4).