# Presentation: 727873

## NHANES IIILinked Mortality File Overview

**Christine S. Cox**
**Special Assistant for Record Linkage**

**Donna Miller, Jim Brittain, Bryan Sayer**

## NHANES III

- Nationally representative survey of the civilian non-institutionalized U.S. population.
- Conducted from 1988 to 1994.
- Sample size of 33,994
- 20,050 respondents who age 17+ at interview eligible for mortality follow-up.
- Collects information on variety of health factors including: health status, risk factors and health behaviors, nutritional status, and physical examination data
- Survey design materials, questionnaires, and analytic reports available from the NCHS web site. http://www.cdc.gov/nchs/nhanes.htm

## National Death Index 

- A centralized electronic data base containing death information from U.S. death certificates
- Available by application for statistical research only
- Users submit records containing study participant data to attempt to match to correct death records
- Each death record contains: demographic characteristics of the decedent, state of death, and  underlying/multiple causes of death
- Current Coverage:  1979-2002
- NDI webpage: http://www.cdc.gov/nchs/r&d/ndi/ndi.htm

## NHANES III-NDI Linkage

- Conducting NDI data linkage is both a scientifically valuable and cost effective data collection activity.
- Provides the opportunity to conduct a wide variety of mortality outcome studies analyzing health conditions and behaviors, along with extensive nutritional intake, examination, and laboratory data.
- Example:  serum cholesterol levels and risk of stroke mortality

## NHANES III – NDI Linkage Methodology

- Based on a probabilistic match to the NDI
- Death information collected through 12/31/2000
- A sample of death certificates was collected for verification purposes
- Final match status assigned by NCHS
- Based on probabilistic match results and death certificate review

## NHANES III Mortality Linkage Results

-  20,050   NHANES III adults
-         26   Ineligible (due to missing data)
-    3,384   Deceased (17% of eligible)
-  16,640   Presumed alive as of Dec 31, 2000

## NHANES III Linked Mortality File Access

- NCHS Research Data Center (RDC)
- Purpose –
- To provide access to restricted data files which data users would not be able to otherwise access
- Accessibility –
- On-site access – NCHS, Hyattsville, MD
- Off-site access - User’s remote location

## User Procedures

- To gain access to NCHS restricted data users must:
- Submit a research proposal	and receive approval
- Sign an affidavit of confidentiality and promise not to use any method to attempt to identify respondents
- Submit data files to be linked with RDC data ahead of time – _all_ linking is conducted by RDC staff
- Subject all output and/or materials removed from the RDC to a _disclosure limitation review_
- Pay a user’s fee that will be estimated prior to proposal approval

## RDC Contact Information

- For general Questions/Comments
- Email: rdca@cdc.gov      Phone: (301)458-4732
- For On-site Info: Negasi Beyene
- Email: NBeyene@cdc.gov    Phone: (301)458-4097
- For Remote Access Info: Vijay Gambhir
- Email: vgambhir@cdc.gov Phone: (301)458-4226

## Linked Mortality File Documentation  

- File documentation will be available soon for download on the NCHS Data Linkage web page (www.cdc.gov/nchs/rd.htm)
- Send email queries to datalinkage@cdc.gov
- Include NHANES III Linked Mortality File in subject line if possible for quicker routing

## NHANES III Linked Mortality File Variables

- NHANES III public use ID number
- Eligibility status indicator
- NDI match results/certificate match results
- Dates of birth, death, interview, examination
- Underlying and multiple causes of death

## Future NHANES Mortality Linkages

- NHANES I Linked Mortality File
- 	Mortality period 1971-2000
- NHANES II Linked Mortality File
- 	Mortality period 1976-2000