• Component Description
• Eligible Sample
• Interview Setting and Mode of Administration
• Quality Assurance & Quality Control
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • RXQ510 - Dr told to take daily low-dose aspirin?
  • RXQ515 - Followed advice, took low-dose aspirin?
  • RXQ520 - Taking low-dose aspirin on your own?
  • RXQ525G - Schedule/frequency of aspirin use
  • RXQ525Q - Another ASA schedule: number of doses
  • RXQ525U - Another ASA schedule: frequency of doses
  • RXD530 - Aspirin dose in milligrams (mg)

National Health and Nutrition Examination Survey

2011-2012 Data Documentation, Codebook, and Frequencies

Preventive Aspirin Use (RXQASA_G)

Data File: RXQASA_G.xpt

First Published: September 2013

Last Revised: NA

Component Description

The NHANES 2011-12 preventive aspirin use questionnaire (RXQASA_G) provides data on low-dose aspirin taken to prevent heart attacks, strokes, and/or cancer. It is the first NHANES data collection specifically designed to estimate the prevalence of low-dose, over the counter preventive aspirin use in the United States. Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the U.S. and taking low dose aspirin is demonstrated to be beneficial for the secondary prevention of CVD (AHA, 2009; USPSTF, 2009). Increasing aspirin use among those persons who are at high risk for CVD is a key U.S. Public Health objective (Frieden & Berwick, 2011).

RXQASA_G data collection topics include:

• Whether a doctor recommended low dose aspirin for preventive use
• Adherence to this medical advice; and whether aspirin was stopped due to side effects
• Whether the low-dose aspirin was taken on one’s own initiative
• The schedule and frequency of aspirin use
• The specific aspirin dose taken

The RXQASA_G data collection format was designed to provide both current and lifetime prevalence estimates of preventive aspirin use: overall use; doctor recommended use and self-initiated use. When combined with other 2011-12 NHANES data, the prevalence of low-dose aspirin use for both primary and secondary prevention can be estimated, as well as the prevalence of aspirin use in key U.S. population subgroups: those with coronary artery disease, angina, heart attack, stroke, and diabetes. Also, preventive aspirin use prevalence can be monitored across the major demographic subgroups such as age, gender and race/ethnicity. Person-level population-based estimates of the distributions of aspirin doses taken and of scheduled frequency of use are also supported. 

Eligible Sample

All survey participants 40 years of age and older are eligible for this subsection questionnaire.

Interview Setting and Mode of Administration

The preventive aspirin use questions were asked, in the home, by trained interviewers using the Computer-Assisted Personal Interviewing (CAPI) system. They were administered as part of the Dietary Supplements and Prescription Medication Section (DSQ) of the Sample Person (SP) Questionnaire, which collects information on dietary supplements, nonprescription antacids and prescription medication. The Interviewer Procedure Manuals and Survey Questionnaires can be found on the NHANES website https://wwwn.cdc.gov/nchs/data/nhanes/2011-2012/questionnaires/dsq.pdf.

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.

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.

The Preventive Aspirin Use questionnaire captured data on the actual dose of aspirin taken by the participant (RXD530). While most survey participants were taking 81mg aspirin, the data for this variable was not grouped or edited, so as to provide data analysts with the actual doses of aspirin reported by the survey participants. These aspirin doses ranged from 25 mg to 500 mg.

Analytic Notes

The analysis of The preventive aspirin use data file (RXQASA_G) is structured differently from the prescription medication data file (RXQ_RX_G). It is formatted as person level data, where each participant has only one record. The low-dose aspirin reported in this data file is usually available over-the-counter without prescription. However, some state laws might require prescriptions for such over-the-counter medications. Also, sometimes physicians might write prescriptions for preventive aspirin. The RXQASA_G data for the most part represents the non-prescription over-the-counter aspirin use however the few instances where prescription aspirin was used for preventive purposes are also included in this data file.

In prior NHANES data collections on over-the-counter and prescription aspirin use, dose information was not captured so it is not possible to distinguish low-dose preventive aspirin use from analgesic aspirin use. The context of data collection for these previous aspirin use data collections was to assess the role of aspirin therapy in arthritis and musculoskeletal pain: NHANES I (1971-75), NHANES II (1976-80), NHANES 2009-10; and to preform surveys of general analgesic use prevalence: NHANES III (1988-94) and NHANES 1999-2004.

The analysis of NHANES 2011–12 aspirin use questionnaire data must be conducted using the appropriate survey design variables, sample weights, and the basic demographic variables. Interview weights should only be used if questionnaire data are analyzed by themselves. However if RXQASA_G data are merged with the MEC examination data or laboratory data, the MEC examination weights should be used for analyses. If RXQASA_G data are merged with laboratory sub-sample data, sub-sample weights should be used for analyses.

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.

References

• American Heart Association (AHA) Guidelines for Primary Prevention of Cardiovascular Disease and Stroke: 2002 Update: Consensus Panel Guide to Comprehensive Risk Reduction for Adult Patients without Coronary or Other Atherosclerotic Vascular Diseases. Circulation. 2002; 106: 388-391.
• Frieden TR, Berwick DM. The "Million Hearts" initiative--preventing heart attacks and strokes. N Engl J Med. 2011 Sep 29;365(13):e27.
• US Preventive Services Task Force (USPSTF). Aspirin for the prevention of cardiovascular disease: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2009; 150: 396-404.

Codebook and Frequencies