NLSY79 Attachment 8: Health Codes

• General Information
• CDC National Vital Statistics System, 113 List
• Modified ICD-9 Codes
• Modified V Codes
• Modified E Codes
• Codes for Parts of Body in Health-related data
• National Death Index (NDI) Data

General Information on Health Codes

Health Conditions Related to Work Limitations (1979-2000)

The health sections of the NLSY79 surveys for most interview years between 1979-2000 elicited reports of health problems that limited the amount or kind of work the respondent could do. These health problems are coded using a modified version of the International Classification of Diseases (ICD-9) codes taken from the World Health Organization, International Classification of Diseases, Ninth Revision, 2 vols., WHO, Geneva, 1977 (vol. 1) and 1978 (vol. 2).

The health consolidation codes present in 1979, 1981 and 1982 represent the most complete description possible of the respondent's main cause of limitation in work gathered from a reading of the whole health section. They were also coded using the modified ICD-9 codes after the rest of the health section has been coded. The health consolidation codes, thus, represent the (proximal) description of the respondent's main cause of limitation in work, and not an underlying cause (remote) preceding the current complaint.

As originally coded, the untruncated NLSY79 health codes corresponded to the ICD-9 codes with the decimal point deleted, except for the supplemental V and E ICD-9 codes. The supplemental ICD-9 codes were modified by dropping the alpha code and adding the remaining numeric portion of the supplemental codes to a larger number. The following numeric conversion was made for the supplemental codes: V codes = 10000+ and E codes = 11000+. (Zero (0) means no health problem). The changes were necessary because alphas are not used as variable values in the NLSY79 data. These ICD-9 codes have then been collapsed further by truncating them by one digit.

A link to the ICD-9 is included below. The NLSY79 modified codes can be tracked back to general disease classifications in the ICD-9 scheme. The supplemental E and V codes and the medical terms associated with them appear in Tables 2-3 below. For more detail, see the International Classification of Diseases, Ninth Revision.

40+, 50+ and 60+ Biological Parent and Respondent Health Conditions (1998-2020)

With the addition of the 40+ Health Module in 1998, questions collecting health conditions for the biological parents of respondents have been asked of the appropriate cohort each round. This has continued with the subsequent 50+ and 60+ Health Modules. In the 50+ and 60+ Health Modules, respondents also have had the opportunity to report any other information they wanted to about their own health. 

The major health conditions of respondents’ biological parents collected in the 40+, 50+ and 60+ Health Modules are coded using the CDC, National Vital Statistics System 113 List, contained in Table 1 below. These are taken from the National Vital Statistics Reports, Volume 65, no 2 (2/16/2016), and can be found online on the CDC website.

Parts of Body Affected by Work-Limiting Health Conditions and Reported Cancer (1979-2018)

A set of numeric codes for parts of the body was developed by NORC for the 1979-1981 health sections. These codes are contained in Table 4. They have been used to code parts of the body affected by work-related injuries/illnesses mentioned above. Additionally, respondents have been asked to report cancer diagnoses and parts of the body affected by these cancers in the 40+, 50+ and 60+ Health Modules. The same codes have been applied to parts of the body affected by cancer.

National Death Index (NDI) Data

The round 29 (2020) data release contains information regarding cause, dates and location of death for deceased respondents for whom a matching death certificate was returned from an NDI search. Most of these variables are limited to the geocode and zipcode releases. Data for a subset of NLSY79 respondents was submitted for an NDI search. The subset included respondents identified as deceased during survey field periods and respondents who have proven difficult to locate or have not been interviewed for a period of time with no confirmation of their status. In order to maximize the possibility of an NDI death certificate match, multiple submissions were made for individual respondents whenever possible. These multiple submissions could include elements such as maiden names, different married names, nicknames and various multiple ethnicities reported by the respondent, any of which might appear in various combinations on a death certificate. Individual respondent records, interviewer notes and administrative data were examined in conjunction with NDI search results to determine those for which valid matches could be established. Related variables are found in the NDI VERIFICATION area of interest. Table 1 below depicts the coding scheme used for the underlying cause of death, found on the 2020 public data release. See also the Health section for information on NDI-related variables.

Table 1: CDC – National Vital Statistics System 113 List (A conversion crosswalk from the ICD-10 health codes and the National Vital Statistics System 113 List codes can be accessed in the file ICD-10 to National Vital Statistics 113 List Crosswalk (XLSX).

Modified ICD-9 Codes

The ICD-9 can be found on the CDC website as well as through many other online resources.  With the exception of the E and V codes (see tables below), the truncated codes contained in the NLSY79 data for health conditions affecting ability to work map directly to general disease classifications in the ICD-9 codes.