Data Resource Center
Code library

National Health and Nutrition Examination Survey (NHANES)

Crosswalks of variable names and codes between NHANES survey cycles

This document provides a crosswalk between key variables for oral health analyses that differ in coding between the NHANES 1988-1994 and NHANES 1999-2002 data sets.

General notes about variable name changes and special codes:

Variables that differ only in name were renamed to the NHANES 1999-2002 names in the programs used for the MMWR Surveillance Summary.

Special codes: 
For many variables, NHANES 1988-1994 used a code “8” for Blank but applicable. 
Variables with codes longer than one digit use strings of 8s to indicate Blank but applicable. 
NHANES 1999-2002 uses a code “7” (or longer strings of 7s) to indicate “Refused”.
These were not recoded, except in variables ending in “x” where these special codes were set to “.” for missing (in the sense of "no data", not in the sense of "missing tooth" as in the "M" in DMFT).

Crosswalks:

Coronal caries examination variables in NHANES 1988-1994, 1999-2000 and 2001-2002

Root caries examination variables in NHANES 1988-1994, 1999-2000 and 2001-2002

Sealant examination variables in NHANES 1988-1994, 1999-2000 and 2001-2002

Enamel fluorosis examination variables in NHANES 1999-2000 and 2001-2002

Incisor trauma examination variables in NHANES 1999-2000 and 2001-2002

Periodontal examination variables in NHANES 1988-1994, 1999-2000 and 2001-2002

Oral health questions in NHANES 1988-1994, 1999-2000 and 2001-2002

Demographics variables in NHANES 1988-1994, 1999-2000 and 2001-2002