Protocol - Current Age

Add to My Toolkit

The interviewer asks the respondent for his or her date of birth in MM/DD/YYYY format. If the respondent does not know his or her date of birth, the interviewer asks an alternative question to determine his or her age. NOTE: The current age of the respondent can be calculated, given the date of the interview.

Specific Instructions

The question may be asked of a proxy. Proxies are others in the household who can answer on behalf of the index person (e.g., parent, spouse) if the index person is too young, incapacitated, deceased, or cannot be located.


What is your birthdate? MM/DD/YYYY;

9[ ]Don’t Know [ask follow-up question];

7[ ]Refused

[Follow-up question if "don’t know":] About how old are you? AGE _______;

999[ ]Don’t Know

7[ ]Refused



Personnel and Training Required

The interviewer must be trained to conduct personal interviews with individuals from the general population. The interviewer must be trained and found to be competent (i.e., tested by an expert) at the completion of personal interviews.* The interviewer should be trained to prompt respondents further if a "don’t know" response is provided.

* There are multiple modes to administer this question (e.g., paper-and-pencil and computer-assisted interviews).

Equipment Needs

While the source instrument was developed to be administered by computer, the PhenX Working Group acknowledges these questions can be administered in a noncomputerized format (i.e., paper-and-pencil instrument). Computer software is necessary to develop computer-assisted instruments. The interviewer will require a laptop computer or handheld computer to administer a computer-assisted questionnaire.

Requirement CategoryRequired
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Interviewer-administered questionnaire


Infant, Toddler, Child, Adolescent, Adult, Senior, Pregnancy


Any age.

Selection Rationale

Age is a primary predictor of disease and the most important potential confounder in epidemiologic studies.

Age at date of interview or exam can be compared to age in future follow-up interviews or exams for longitudinal research purposes.

Vetted against several other current age questions, the National Health and Nutrition Examination Survey (NHANES) question was selected because it included the date of birth (DOB) and a follow-up question to collect current age if the respondent did not know his or her DOB.


Chinese, English, Spanish

caDSR Common Data Elements (CDE) Birth Date 2201154 CDE Browser
Logical Observation Identifiers Names and Codes (LOINC) Current age proto 62293-6 LOINC
Derived Variables

Age at onset, present age

Process and Review

The Expert Review Panel #2 (ERP 2) reviewed the measures in the Demographics, Environmental Exposures, and Social Environments domains.

Guidance from ERP 2 includes:

• No significant changes to measure

Back-compatible: no changes to Data Dictionary

Previous version in Toolkit archive (link)

Protocol Name from Source

National Health and Nutrition Examination Survey (NHANES), 2005-2006


National Center for Health Statistics. National Health and Nutrition Examination Survey (NHANES), Screener Module 1, 2005–2006. Question numbers: SCQ.290 and SCQ.292.

General References

Public Population Project in Genomics (P3G) Data Shaper.

Protocol ID


Export Variables
Variable Name Variable IDVariable DescriptiondbGaP Mapping
PX010101020000 About how old are you? Variable Mapping
PX010101020100 About how old are you? N/A
PX010101010400 What is your birthdate? N/A
PX010101010200 What is your birthdate? Day Variable Mapping
PX010101010100 What is your birthdate? Month Variable Mapping
PX010101010300 What is your birthdate? Year Variable Mapping
Measure Name

Current Age

Release Date

February 6, 2009


Question to determine the respondent’s current age using his or her date of birth.


Current age is a critical component of a respondent’s demographic background. Date of birth (DOB)/current age is essential to medical research because it captures the age at the time of the clinical visit or diagnosis. Age is related to nearly all diseases and conditions and is the strongest potential confounder of other effects on these processes. Current age is often used to stratify respondents for more valid comparison (e.g., obesity of males aged 40-45 in Mississippi).


current age, Demographics, National Center for Health Statistics, NCHS, Centers for Disease Control and Prevention, CDC, age, date of birth, DOB, National Health and Nutrition Examination Survey, NHANES, Demographics-Populations with HD

Measure Protocols
Protocol ID Protocol Name
10101 Current Age