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.
A nine-item depression screening instrument (variable prefix is DPQ), also called the Patient Health Questionnaire (Kroenke and Spitzer, 2002; Kroenke et al., 2001) was administered to determine the frequency of depression symptoms over the past 2 weeks. For each symptom question, points ranging from 0 to 3, are associated with the response categories "not at all," "several days," "more than half the days," and "nearly every day.” This screening instrument incorporates DSM-IV depression diagnostic criteria (Spitzer et al.,1999).
Participants aged 12 years and over in the NHANES 2017-March 2020 pre-pandemic sample were eligible. Only data from participants aged 18 and older are included in this data file. Participants requiring a proxy were not eligible because of the sensitive nature of the questions. Data for youth aged 12-17 years are available through the NCHS Research Data Center.
Interview Setting and Mode of Administration
The questions were asked at the Mobile Examination Center (MEC), by trained interviewers, using the Computer-Assisted Personal Interview (CAPI) system as part of the MEC interview.
Quality Assurance & Quality Control
The CAPI system is programmed with built-in consistency checks to reduce data entry errors.
Data Processing and Editing
Edits were made to ensure completeness, consistency, and analytic usefulness of the data.
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 from 18 locations 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 examination 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.
A total score, ranging from 0 to 27, can be calculated for persons who have complete responses to the symptom questions. Major depression and depression severity can be assessed using pre-defined cut-points, described in the references.
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.