Table of Contents

Component Description

The fasting questionnaire is administered to determine the fasting status of the survey participant. Questions include but are not limited to:  length of “food” fast, whether the participant had gum or mints, coffee or tea, or alcohol or dietary supplements prior to their laboratory examination.

Eligible Sample

Examined participants aged 1 year and older were eligible.

Description of Laboratory Methodology

The MEC phlebotomist administered the questionnaire to determine the fasting status of the survey participant.

There were no changes to the questionnaire or lab site for this component in the NHANES 2017-2018 cycle.

Laboratory Quality Assurance and Monitoring

Detailed instructions on specimen collection and processing are discussed in the NHANES Laboratory Procedures Manual (LPM).The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Amendments mandates. Detailed QA/QC instructions are discussed in the NHANES LPM. 

Data Processing and Editing

Fasting questionnaire data were recorded directly into a computerized database; all forms used in the MEC were automated.

Analytic Notes

Refer to the 2017-2018 Laboratory Data Overview for general information on NHANES laboratory data.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted using the appropriate survey design and demographic variables. The NHANES 2017-2018 Demographics File contains demographic data, health indicators, and other related information collected during household interviews as well as the sample weight variables. The recommended procedure for variance estimation requires use of stratum and PSU variables (SDMVSTRA and SDMVPSU, respectively) in the demographic data file.

This Fasting Questionnaire File includes auxiliary information such as fasting status, length of fast, and the time of venipuncture. 

This laboratory data file can be linked to the other NHANES data files using the unique survey participant identifier (i.e., SEQN).

Use PHAFSTHR and PHAFSTMN to determine the duration of fasting in hours and minutes, respectively. When calculating a fasting time in hours and minutes, pay careful attention to the other times in hours and minutes. For example, the survey participants were asked: "When was the last time you ate or drank anything other than plain water? Do not include diet soda or black coffee or tea with artificial sweeteners like Sweet'N Low, NutraSweet, Equal, or Splenda." Survey participants were then asked questions PHQ020 to PHQ060: "Have you had any of the following since the last time you ate or drank anything other than plain water? Coffee or tea with cream or sugar (include milk or non-dairy creamers); Alcohol, such as beer, wine, or liquor; Gum, breath mints, lozenges, cough drops, or cold remedies; Antacids, laxatives, or anti-diarrheal; Dietary supplements such as vitamins and minerals."

If you are using fasting status in any of your analyses, please consider the answers to PHACOFHR/PHACOFMN, PHAALCHR/PHAALCMN, PHAGUMHR/PHAGUMMN/ PHAANTHR/PHAANTMN, and PHASUPHR/PHASUPMN with the times in hours and minutes in addition to the PHAFSTHR and PHSFSTMN times.

Use PHDSESN to determine the session in which the participant was examined.

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.

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 1 YEARS - 150 YEARS

PHQ020 - Coffee or tea with cream or sugar?

Variable Name:
PHQ020
SAS Label:
Coffee or tea with cream or sugar?
English Text:
Coffee or tea with cream or sugar? [Include milk or non-dairy creamers.]
English Instructions:
Have you had any of the following since " today at" or "yesterday at" fasting time in PHQ010.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 118 118
2 No 7878 7996
. Missing 370 8366

PHACOFHR - Coffee/tea fast time (hours)

Variable Name:
PHACOFHR
SAS Label:
Coffee/tea fast time (hours)
English Text:
The time (in hours) since the examinee last drank coffee or tea with cream or sugar.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 17 Range of Values 118 118
. Missing 8248 8366

PHACOFMN - Coffee/tea fast time (minutes)

Variable Name:
PHACOFMN
SAS Label:
Coffee/tea fast time (minutes)
English Text:
The time (in minutes) since the examinee last drank coffee or tea with cream or sugar.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 59 Range of Values 118 118
. Missing 8248 8366

PHQ030 - Alcohol, such as beer, wine, or liquor?

Variable Name:
PHQ030
SAS Label:
Alcohol, such as beer, wine, or liquor?
English Text:
Alcohol, such as beer, wine, or liquor?
English Instructions:
Have you had any of the following since "today at" or "yesterday at" the fasting time in PHQ010.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 39 39
2 No 7957 7996
. Missing 370 8366

PHAALCHR - Alcohol fast time (hours)

Variable Name:
PHAALCHR
SAS Label:
Alcohol fast time (hours)
English Text:
The time (in hours) the examinee last drank alcohol such as beer, wine, or liquor.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 17 Range of Values 39 39
. Missing 8327 8366

PHAALCMN - Alcohol fast time (minutes)

Variable Name:
PHAALCMN
SAS Label:
Alcohol fast time (minutes)
English Text:
The time (in minutes) the examinee last drank alcohol such as beer, wine, or liquor.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 59 Range of Values 39 39
. Missing 8327 8366

PHQ040 - Gum, mints, lozenges or cough drops

Variable Name:
PHQ040
SAS Label:
Gum, mints, lozenges or cough drops
English Text:
Gum, breath mints, lozenges or cough drops, or other cough or cold remedies?
English Instructions:
Have you had any of the following since "today at" or "yesterday at" the fasting time in PHQ010?
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 167 167
2 No 7829 7996
. Missing 370 8366

PHAGUMHR - Gum, mints cough drops fast time (hours)

Variable Name:
PHAGUMHR
SAS Label:
Gum, mints cough drops fast time (hours)
English Text:
The time (in hours) the examinee last had gum, breath mints, lozenges or cough drops, or other cough or cold remedies.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 16 Range of Values 167 167
. Missing 8199 8366

PHAGUMMN - Gum, mints, cough fast time (minutes)

Variable Name:
PHAGUMMN
SAS Label:
Gum, mints, cough fast time (minutes)
English Text:
The time (in minutes) the examinee last had gum, breath mints, lozenges or cough drops, or other cough or cold remedies.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 59 Range of Values 167 167
. Missing 8199 8366

PHQ050 - Antacids, laxatives, or anti-diarrheals?

Variable Name:
PHQ050
SAS Label:
Antacids, laxatives, or anti-diarrheals?
English Text:
Antacids, laxatives, or anti-diarrheals?
English Instructions:
Have you had any of the following since "today at" or "yesterday at" the fasting time in PHQ010.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 65 65
2 No 7931 7996
. Missing 370 8366

PHAANTHR - Antacids, laxatives fast time (hours)

Variable Name:
PHAANTHR
SAS Label:
Antacids, laxatives fast time (hours)
English Text:
The time (in hours) the examinee last had antacids, laxatives or anti-diarrheals.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 16 Range of Values 65 65
. Missing 8301 8366

PHAANTMN - Antacids, laxatives fast time (minutes)

Variable Name:
PHAANTMN
SAS Label:
Antacids, laxatives fast time (minutes)
English Text:
The time (in minutes) the examinee last had antacids, laxatives or anti-diarrheals.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 57 Range of Values 65 65
. Missing 8301 8366

PHQ060 - Dietary supplements?

Variable Name:
PHQ060
SAS Label:
Dietary supplements?
English Text:
Dietary supplements such as vitamins and minerals? [Include multivitamins and single nutrient supplements.]
English Instructions:
Have you had any of the following since "today at" or "yesterday at" the fasting time in PHQ010.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 137 137
2 No 7859 7996
. Missing 370 8366

PHASUPHR - Dietary supplements fast time (hours)

Variable Name:
PHASUPHR
SAS Label:
Dietary supplements fast time (hours)
English Text:
The time (in hours) the examinee last had dietary supplements such as vitamins and minerals.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 16 Range of Values 137 137
. Missing 8229 8366

PHASUPMN - Dietary supplements fast time (minutes)

Variable Name:
PHASUPMN
SAS Label:
Dietary supplements fast time (minutes)
English Text:
The time (in minutes) the examinee last had dietary supplements such as vitamins and minerals.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 59 Range of Values 137 137
. Missing 8229 8366

PHAFSTHR - Total length of "food fast," hours

Variable Name:
PHAFSTHR
SAS Label:
Total length of "food fast," hours
English Text:
The time (in hours) between when the examinee last ate or drank anything other than water and the time of the venipuncture.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 38 Range of Values 7996 7996
. Missing 370 8366

PHAFSTMN - Total length of "food fast," minutes

Variable Name:
PHAFSTMN
SAS Label:
Total length of "food fast," minutes
English Text:
The time (in minutes) between when the examinee last ate or drank anything other than water and the time of the venipuncture.
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 59 Range of Values 7996 7996
. Missing 370 8366

PHDSESN - Session in which SP was examined

Variable Name:
PHDSESN
SAS Label:
Session in which SP was examined
English Text:
Session in which SP was examined
Target:
Both males and females 1 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 morning 3818 3818
1 afternoon 3153 6971
2 evening 1395 8366
. Missing 0 8366