Table of Contents

Locator Record

Title: Prescription Medications (RXQ_RX_F )
Contact Number: 1-866-441-NCHS
Years of Content: 2009 - 2010
First Published: May, 2012
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:The Prescription Medication subsection provides personal interview data on use of prescription medications during a one-month period prior to the survey date
Record Source: NHANES 2009 - 2010
Survey Methodology: NHANES 2009 - 2010 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

The Dietary Supplement and Prescription Medication Section (DSQ) of the Sample Person (SP) Questionnaire, collects information on 1) dietary supplements, 2) nonprescription antacids, 3) prescription medications, and 4) asthma medications.

The Prescription Medication subsection provides personal interview data on use of prescription medications during a one-month period prior to the survey date. The NHANES 2009–2010 prescription medication questions are similar to the NHANES 1999–2008 and NHANES III, 1988–1994 questions.

Eligible Sample

All survey participants are eligible for the prescription medication questions.

Interview Setting and Mode of Administration

The Prescription Medication questionnaire was asked, in the home, by trained interviewers using the Computer-Assisted Personal Interviewing (CAPI) system. Participants over 16 years of age answered for themselves; A proxy provided information for survey participants who were under 16 years of age and for individuals who could not answer the questions themselves.

The Interviewer Procedure Manuals and Survey Questionnaires can be found on the NHANES website (http://www.cdc.gov/nchs/data/nhanes/nhanes_09_10/dsq_f.pdf).

Quality Assurance & Quality Control

Data were routinely examined for discrepancies and erroneous entries. All drug names entered by the interviewer were compared to the medication name selected from the database. Review of the 2009–2010 data found that 92% of all reported drugs were automatically matched to the data collection drug database. The 8%, which were not matched to the drug database, were edited after data collection at NCHS. The most common reasons for a non-match were incorrect spelling of the drug, insufficient detail to identify the drug, and reporting of a nonprescription product that was not in the drug database. Details of the editing process are described below.

Data Processing and Editing

Data Collection Methods

During the household interview survey participants are asked if they have taken medications in the past 30 days for which they needed a prescription. Those who answer "yes" are asked to show the interviewer the medication containers of all the products used. For each medication reported, the interviewer enters the product’s complete name from the container into a computer. If no container is available, the interviewer asks the participant to verbally report the name of the medication.

When the interviewer enters the medication name into the computer, the name is automatically matched to a prescription drug database on the computer to identify an exact match or similar text matches (refer below for details on the prescription medication database). The interviewer then selects the best match from a list of possible matches. The original entry of the interviewer and the product selected from the computer list are saved under separate variables for quality control purposes. If an exact match of the medication cannot be found, the interviewer is instructed to select "drug not found on list" from the list. Interviewers can record up to 20 prescription medications. Participants are also asked how long they had been taking the medication and the main reason for use.

The NHANES 2009–2010 prescription medication questions can be accessed in the Dietary Supplements and Prescription Medications Section of the Sample Person Questionnaire (http://www.cdc.gov/nchs/data/nhanes/nhanes_09_10/dsq_f.pdf).

Prescription Medication Questions Included in this Data Release

Prescription Medication Database for Data Collection

NCHS used the Lexicon Plus®, a proprietary database of Cerner Multum, Inc. to assist in data collection. The Lexicon Plus® is a comprehensive database of all prescription and some nonprescription drug products available in the U.S. drug market. For NHANES, the Lexicon Plus® files were modified and uploaded to a laptop computer and incorporated into a search engine for use by interviewers in the field. The computer file is updated at the beginning of each survey year to incorporate changes to the Lexicon Plus® and include products approved and available to the U.S. public in the prior year.

Data Editing

General editing of data:

When a variable was modified globally, as part of the editing process, the third letter in the variable name was changed from a Q (i.e. RXQ) to a D (i.e. RXD). For example, variables that were obtained from an external drug database will have the letter "D" in the third position of the variable name.

Prescription medications incorrectly reported in other subsections of questionnaire:

Prescription antacids that were incorrectly reported in the nonprescription antacid section of the questionnaire were removed from the antacid file and added to the prescription medication file.

Prescription supplements are released in the Dietary Supplements Data File. Some prescription medications were mistakenly recorded in the dietary supplement section. These were removed from that file and added to the prescription medication file. Any prescription dietary supplement that was incorrectly reported in the prescription medication section was removed from the prescription medication section and moved to the dietary supplement section. The following products were moved to the dietary supplements files:

All prescription niacin, potassium, and sodium products were retained in the prescription medication file.

Products reported in the prescription medication section that were only available as an over-the-counter product during 2009–2010 were removed from the prescription medication file, except over-the-counter insulin, and products containing pseudoephedrine.

Specific variables and edits:

RXDUSE: Have you taken or used any prescription medicines in the past month?

This variable was the lead-in question to the series of questions on prescription medication use. It accounts for all prescription medications except prescription dietary supplements which are included in the dietary supplement files (DSQ). A small number of persons refused to answer this question (coded 7) or did not know whether they used a prescription medication in the past month (coded 9).
This variable was edited and takes into account prescription medications reported in this section as well as prescription medications moved into this file from the dietary supplements or nonprescription antacids sections of the questionnaire.

RXDCOUNT: The number of prescription medicines taken

This variable was computed at NCHS and represents the total number of prescription medications reported by the respondent, including those drugs identified as unknown (RXDDRUG = 55555). The count has been adjusted for all prescription medications moved into and those moved out of the prescription medication section. However, the count is not a comprehensive count of all prescription medications used by a participant because prescription dietary supplements are part of the dietary supplement section. There were also participants who reported the use of a prescription medication in the past month (RXDUSE = 1) but did not know the name of the medication (RXDDRUG = 99999) or refused to report the name of the medication (RXDDRUG = 77777). Each product reported as refused or don’t know is still included in the total count of prescription medications used under RXDCOUNT.

RXQSEEN: Medicine container seen by interviewer?

There was no editing of this variable.

RXDDAYS: For how long have you been taking this medicine?

This variable was created from a two-part (number and unit) question and indicates how long the respondent reported taking each prescription medication. Responses were recorded in days, weeks, months, and years. To facilitate analysis, all answers were converted to days using conversion factors of 7 days per week, 30.4 days per month, and 365 days per year. There were persons who reported the use of a prescription medication but did not know how long they had been using the medication (RXDDAYS = 99999) or refused to report the length of use (RXDDAYS = 77777). There were also persons who reported the use of a prescription medication but did not report the length of use. RXDDAYS is missing for those persons.

Drug Database for Data Release:

NCHS used the Lexicon Plus®, a proprietary database of Cerner Multum, Inc. to assist with data editing and release. The December 2010 Multum Lexicon database was used for creating the RXQ_RX_F data release file. For additional information refer to the RXQ_DRUG documentation.

In accordance with the license agreement, NCHS publications, tabulations, and software applications should cite the Multum Lexicon as the source and basis for the coding and classification of the NHANES drug data.

Creation of additional data release variables:

RXDDRUG: Generic drug name

All reported drug names were converted to a standard generic drug name for data release. For multi-ingredient products, the ingredients are listed in alphabetical order (i.e., Acetaminophen; Codeine).

There were participants who reported the use of a prescription medication but did not know the name of the drug or refused to report the name. These entries were coded as don’t know (99999) and refused (77777), respectively. There were also medications reported with insufficient detail to accurately identify the exact product, but there was some information about the therapeutic class of the drug. These products have been released with Multum's therapeutic category name followed by "- unspecified" (e.g., anti-infective - unspecified; hormones/hormone modifiers - unspecified). The names of a limited number of reported drugs could not be identified by NCHS as a known prescription product. These entries are counted as prescription medications, since there is no evidence that they are not, and have been coded as 55555, unknown drug.

RXDDRGID: Generic drug code

Each generic drug name is associated with a unique generic drug code from Multum's Lexicon Drug Database. There were some drug names reported by NHANES' participants that were not found in the Lexicon Drug Database. These have been assigned unique drug codes beginning with an "a" or "h". Unspecified products with known therapeutic action have drug codes beginning with a "c" and are followed by their respective Multum therapeutic category code. RXDDRGID is missing for unknown drugs (55555), refused (77777), or don’t know (99999) RXDDRUG entries.

Therapeutic class codes associated with a drug are found in a separate data release file, RXQ_DRUG.

There are two files related to the prescription drug data. The contents of each file are described below. The files can be linked by the variable RXDDRGID.

The file named RXQ_RX_F contains data on all survey participants and their use of a prescription drug. Participants who reported the use of multiple prescription drugs will have multiple records, that is, a record for each drug.

The file named RXQ_DRUG contains therapeutic drug class information on all drugs reported by NHANES participants from 1988-1994 through 2009-2010. It contains drug (up to 4) and ingredient (up to 6) therapeutic category codes for each drug. It also has a variable that identifies if the drug is made up of a single or multiple ingredients.

RXQ_RX_F: Participant's Use of Prescription Drug(s)
Variable Name Label
SEQN Respondent sequence number
RXDUSE Taken prescription medicine, past month
RXDDRUG Generic drug name
RXDDRGID Generic drug code
RXQSEEN Medicine container seen by interviewer
RXDDAYS Number of days taken medicine
RXDCOUNT Number of prescription medicines taken

RXQ_DRUG: Drug Information
Variable Name Label
RXDDRGID GENERIC DRUG CODE
RXDDRUG GENERIC DRUG NAME
RXDINGFL SINGLE/MULTIPLE INGREDIENT DRUG
RXDDCI1A DRUG CATEGORY ID - CATEGORY 1, LEVEL 1
RXDDCI1B DRUG CATEGORY ID - CATEGORY 1, LEVEL 2
RXDDCI1C DRUG CATEGORY ID - CATEGORY 1, LEVEL 3
RXDDCI2A DRUG CATEGORY ID - CATEGORY 2, LEVEL 1
RXDDCI2B DRUG CATEGORY ID - CATEGORY 2, LEVEL 2
RXDDCI2C DRUG CATEGORY ID - CATEGORY 2, LEVEL 3
RXDDCI3A DRUG CATEGORY ID - CATEGORY 3, LEVEL 1
RXDDCI3B DRUG CATEGORY ID - CATEGORY 3, LEVEL 2
RXDDCI3C DRUG CATEGORY ID - CATEGORY 3, LEVEL 3
RXDDCI4A DRUG CATEGORY ID - CATEGORY 4, LEVEL 1
RXDDCI4B DRUG CATEGORY ID - CATEGORY 4, LEVEL 2
RXDDCI4C DRUG CATEGORY ID - CATEGORY 4, LEVEL 3
RXDDCN1A DRUG CATEGORY NAME - CATEGORY 1, LEVEL 1
RXDDCN1B DRUG CATEGORY NAME - CATEGORY 1, LEVEL 2
RXDDCN1C DRUG CATEGORY NAME - CATEGORY 1, LEVEL 3
RXDDCN2A DRUG CATEGORY NAME - CATEGORY 2, LEVEL 1
RXDDCN2B DRUG CATEGORY NAME - CATEGORY 2, LEVEL 2
RXDDCN2C DRUG CATEGORY NAME - CATEGORY 2, LEVEL 3
RXDDCN3A DRUG CATEGORY NAME - CATEGORY 3, LEVEL 1
RXDDCN3B DRUG CATEGORY NAME - CATEGORY 3, LEVEL 2
RXDDCN3C DRUG CATEGORY NAME - CATEGORY 3, LEVEL 3
RXDDCN4A DRUG CATEGORY NAME - CATEGORY 4, LEVEL 1
RXDDCN4B DRUG CATEGORY NAME - CATEGORY 4, LEVEL 2
RXDDCN4C DRUG CATEGORY NAME - CATEGORY 4, LEVEL 3
RXDICI1A INGREDIENT CATEGORY ID - CATEGORY 1, LEVEL 1
RXDICI1B INGREDIENT CATEGORY ID - CATEGORY 1, LEVEL 2
RXDICI1C INGREDIENT CATEGORY ID - CATEGORY 1, LEVEL 3
RXDICI2A INGREDIENT CATEGORY ID - CATEGORY 2, LEVEL 1
RXDICI2B INGREDIENT CATEGORY ID - CATEGORY 2, LEVEL 2
RXDICI2C INGREDIENT CATEGORY ID - CATEGORY 2, LEVEL 3
RXDICI3A INGREDIENT CATEGORY ID - CATEGORY 3, LEVEL 1
RXDICI3B INGREDIENT CATEGORY ID - CATEGORY 3, LEVEL 2
RXDICI3C INGREDIENT CATEGORY ID - CATEGORY 3, LEVEL 3
RXDICI4A INGREDIENT CATEGORY ID - CATEGORY 4, LEVEL 1
RXDICI4B INGREDIENT CATEGORY ID - CATEGORY 4, LEVEL 2
RXDICI4C INGREDIENT CATEGORY ID - CATEGORY 4, LEVEL 3
RXDICI5A INGREDIENT CATEGORY ID - CATEGORY 5, LEVEL 1
RXDICI5B INGREDIENT CATEGORY ID - CATEGORY 5, LEVEL 2
RXDICI5C INGREDIENT CATEGORY ID - CATEGORY 5, LEVEL 3
RXDICI6A INGREDIENT CATEGORY ID - CATEGORY 6, LEVEL 1
RXDICI6B INGREDIENT CATEGORY ID - CATEGORY 6, LEVEL 2
RXDICI6C INGREDIENT CATEGORY ID - CATEGORY 6, LEVEL 3
RXDICN1A INGREDIENT CATEGORY NAME - CATEGORY 1, LEVEL 1
RXDICN1B INGREDIENT CATEGORY NAME - CATEGORY 1, LEVEL 2
RXDICN1C INGREDIENT CATEGORY NAME - CATEGORY 1, LEVEL 3
RXDICN2A INGREDIENT CATEGORY NAME - CATEGORY 2, LEVEL 1
RXDICN2B INGREDIENT CATEGORY NAME - CATEGORY 2, LEVEL 2
RXDICN2C INGREDIENT CATEGORY NAME - CATEGORY 2, LEVEL 3
RXDICN3A INGREDIENT CATEGORY NAME - CATEGORY 3, LEVEL 1
RXDICN3B INGREDIENT CATEGORY NAME - CATEGORY 3, LEVEL 2
RXDICN3C INGREDIENT CATEGORY NAME - CATEGORY 3, LEVEL 3
RXDICN4A INGREDIENT CATEGORY NAME - CATEGORY 4, LEVEL 1
RXDICN4B INGREDIENT CATEGORY NAME - CATEGORY 4, LEVEL 2
RXDICN4C INGREDIENT CATEGORY NAME - CATEGORY 4, LEVEL 3
RXDICN5A INGREDIENT CATEGORY NAME - CATEGORY 5, LEVEL 1
RXDICN5B INGREDIENT CATEGORY NAME - CATEGORY 5, LEVEL 2
RXDICN5C INGREDIENT CATEGORY NAME - CATEGORY 5, LEVEL 3
RXDICN6A INGREDIENT CATEGORY NAME - CATEGORY 6, LEVEL 1
RXDICN6B INGREDIENT CATEGORY NAME - CATEGORY 6, LEVEL 2
RXDICN6C INGREDIENT CATEGORY NAME - CATEGORY 6, LEVEL 3

Analytic Notes

The variable RXDCOUNT provides a count of all prescription products reported in the prescription medication section adjusting for products moved into or out of the final file. The count includes products reported as "refused" or "don't know" by participants who reported they had taken a prescription medication but did not know the name of the medication or refused to report the name of the medication. Drugs released as "unknown drug" are also included in the count. However, prescription supplements in the Dietary Supplements File are not included in the total count. Therefore, this variable does not provide a comprehensive count of all prescription products used by the survey participants.

In some cases it may appear as though respondents reported the same prescription drug more than once. That is, the same generic ingredient name and product code may be listed more than once. There are a several reasons for these duplications. Respondents may have reported different brand name medications which had the same generic ingredient name (e.g., "Oxycontin" vs. "Roxicodone"), the medications may have been different forms or dosages of the same product (e.g., Albuterol "oral tablet" vs. "inhalation solution", or Furosemide "20 mg" vs. "40 mg"), or the participant may have reported different lengths of use or reasons for use of the products.

During the data editing process, outlier values were examined. When there was insufficient information to conclude that values were invalid, they were left in the data set. Analysts should examine the distribution of the data and consider whether or not it is appropriate to include or exclude extreme values in a given analysis.

Respondent sequence number (SEQN) in the prescription medication data is not a unique identifier. Participants who reported the use of multiple prescription drugs will have multiple records, that is, a record for each drug. Analysts should convert a drug level data to a personal level data, that is, a record for each person, before merging it with NHANES demographic and other data files by using SEQN.

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.

For details on the quality control/quality assurance process for this component, please refer to the NHANES 2009-2010 Interviewer Procedure Manuals on the NHANES website.

 

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 0 YEARS - 150 YEARS

RXDUSE - Taken prescription medicine, past month

Variable Name:
RXDUSE
SAS Label:
Taken prescription medicine, past month
English Text:
In the past month have you used or taken medication for which a prescription is needed? Do not include prescription vitamins or minerals you may have already told me about.
Target:
Both males and females 0 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 14889 14889
2 No 6008 20897 End of Section
7 Refused 3 20900 End of Section
9 Don't know 4 20904 End of Section
. Missing 1 20905

RXDDRUG - Generic drug name

Variable Name:
RXDDRUG
SAS Label:
Generic drug name
English Text:
Generic drug name
Target:
Both males and females 0 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Generic drug name Value was recorded 14818 14818
55555 Unknown 3 14821
77777 Refused 12 14833
99999 Don't know 56 14889
< blank > Missing 6016 20905

RXDDRGID - Generic drug code

Variable Name:
RXDDRGID
SAS Label:
Generic drug code
English Text:
Generic drug code
Target:
Both males and females 0 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Generic drug code Value was recorded 14818 14818
< blank > Missing 6087 20905

RXQSEEN - Medicine container seen by interviewer

Variable Name:
RXQSEEN
SAS Label:
Medicine container seen by interviewer
English Text:
Was prescription container seen by interviewer?
Target:
Both males and females 0 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 11512 11512
2 No 3305 14817
. Missing 6088 20905

RXDDAYS - Number of days taken medicine

Variable Name:
RXDDAYS
SAS Label:
Number of days taken medicine
English Text:
For how long have you been using or taking {PRODUCT NAME}?
Target:
Both males and females 0 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 27010 Range of Values 14587 14587
77777 Refused 4 14591
99999 Don't know 224 14815
. Missing 6090 20905

RXDCOUNT - Number of prescription medicines taken

Variable Name:
RXDCOUNT
SAS Label:
Number of prescription medicines taken
English Text:
The number of prescription medicines reported
Target:
Both males and females 0 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 20 Range of Values 14889 14889
. Missing 6016 20905