The NHANES program suspended field operations in March 2020 due to the coronavirus disease 2019 (COVID-19) pandemic. As a result, data collection for the NHANES 2019-2020 cycle was not completed and the collected data are not nationally representative. Therefore, data collected from 2019 to March 2020 were combined with data from the NHANES 2017-2018 cycle to form a nationally representative sample of NHANES 2017-March 2020 pre-pandemic data. These data are available to the public. Please refer to the Analytic Notes section for more details on the use of the data.
The Cardiovascular Disease and Health section (variable name prefix CDQ) provides participant-level interview data on evaluating cardiovascular health and includes questions to assess the presence of angina pectoris as defined by the Rose questionnaire.
All participants, 40 years and older, in the NHANES 2017-March 2020 pre-pandemic sample are included in this dataset.
Interview Setting and Mode of Administration
The questionnaire was asked, in the home, by trained interviewers using Computer-Assisted Personal Interview (CAPI) system. A proxy provided information for survey participants who could not answer the questions themselves. The respondent selected the language of interview (English or Spanish) or requested that an interpreter be used. Hand cards, showing response choices or information that survey participants needed to answer the questions, were used for some questions. The hand cards were printed in English, Spanish, Mandarin Chinese (both traditional and simplified), Korean, and Vietnamese. The interviewer directed the respondent to the appropriate hand card during the interview. When necessary, the interviewer further assisted the respondent by reading the response choices listed on the hand cards.
The NHANES 2017-2018 and 2019-2020 questionnaires are available on the NHANES website.
Quality Assurance & Quality Control
The CAPI system is programmed with built-in consistency checks to reduce data entry errors. CAPI also uses online help screens to assist interviewers in defining key terms used in the questionnaire.
After collection, interview data were reviewed by the NHANES field office staff for accuracy and completeness of selected items. The interviewers were required to audio-record interviews and the recorded interviews were reviewed by NCHS staff and interviewer supervisors.
Data Processing and Editing
Frequency counts were checked, “skip” patterns were verified, and the reasonableness of question responses was reviewed. Edits were made to some variables to ensure the completeness, consistency, and analytic usefulness of the data. Edits were also made, when necessary, to address data disclosure concerns.
The COVID-19 pandemic required suspension of NHANES 2019-2020 field operations in March 2020 after data were collected in 18 of the 30 survey locations in the 2019-2020 sample. Because the collected data were not nationally representative, these data were combined with data from the previous cycle (2017-2018) to create a 2017-March 2020 pre-pandemic data file. A special weighting process was applied to the 2017-March 2020 pre-pandemic data file. The resulting sample weights in the demographic data file should be used to calculate estimates from the combined cycles. These sample weights are not appropriate for independent analyses of the 2019-2020 data and will not yield nationally representative results for either the 2017-2018 data alone or the 2019-March 2020 data alone. Please refer to the NHANES website for additional information for the NHANES 2017-March 2020 pre-pandemic data, and for the previous 2017-2018 public use data file with specific weights for that 2-year cycle.
Since the questionnaire was asked during the household interview, the interview sample weights should be used in the analysis. However, if the data is joined with data from the Mobile Exam Center (MEC), the MEC sample weights should be used.
Rose questionnaire criteria (Rose, 1968):
Grade 1 Angina is defined as CDQ001 = 1 and CDQ002 = 1 (but CDQ003 ≠ 1) and CDQ004 = 1 and CDQ005 = 1 and CDQ006 = 1, plus either (CDQ009D = 4 or CDQ009E = 5) or (CDQ009F = 6 and CDQ009G = 7).
Grade 2 Angina is defined as CDQ001 = 1 and CDQ002 = 1 and CDQ003 = 1 and CDQ004 = 1 and CDQ005 = 1 and CDQ006 = 1, plus either (CDQ009D = 4 or CDQ009E = 5) or (CDQ009F = 6 and CDQ009G = 7).
Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.