Characteristics that predict locating and interviewing mothers identified by a state birth defects registry and vital records.
BACKGROUND
State vital records are often used to select population-based controls in record-linkage studies of birth defects. However, locating and contacting individuals based on these data sources to collect additional data can be a challenge.


METHODS
A large case-control study of air quality and birth defects was conducted in 7 Texas counties in which cases were selected from the Texas Birth Defects Registry and controls from state vital records. In 2004, data from these sources were used to trace mothers of cases and controls who delivered babies in the year 2000 (n=2477) for participation in a computer-assisted telephone interview. A number of factors that predicted whether an individual would be located and interviewed were identified.


RESULTS
Between March and August 2004, 38% of the mothers were located, and 38% of the located mothers were interviewed. Case mothers were more likely than control mothers to be located (44 vs. 30%) and, if located, to be interviewed (43 vs. 31%). We compared the characteristics of mothers who were not located (case n=760; control n=777), mothers who were located but not interviewed (case n=344; control n=236), and mothers who were interviewed (case n=256; control n=104). Among both cases and controls, older mothers (>or=30 years) were more likely than younger mothers to be located, and non-Hispanic black mothers were least likely to be located and interviewed.


CONCLUSIONS
Despite the utility of vital records as a source of population-based controls in record-linkage analyses, the poor response rate discourages the use of these data sources to contact individuals for a follow-up study 4 years after delivery.
Gilboa
Suzanne M
SM
Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Mendola
Pauline
P
Olshan
Andrew F
AF
Savitz
David A
DA
Herring
Amy H
AH
Loomis
Dana
D
Langlois
Peter H
PH
Keating
Kristen
K
D016022:Case-Control Studies; D000013:Congenital Abnormalities / Q000145:classification / Q000453:epidemiology*; D003625:Data Collection; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008423:Maternal Age; D008498:Medical Record Linkage; D009035:Mothers / Q000706:statistics & numerical data*; D015999:Multivariate Analysis; D011247:Pregnancy; D012042:Registries; D012189:Retrospective Studies; D013781:Texas / Q000453:epidemiology; D014798:Vital Statistics