Comparability of data obtained from migrant farmworkers and their spouses on occupational history.
BACKGROUND
Epidemiologic studies, particularly case-control studies, often rely on proxy respondents to provide information about subjects' occupational histories. The quality of proxy-reported information in occupational histories has never been evaluated for migrant farmworkers.


METHODS
We compared occupational histories self-reported by 31 farmworkers with those reported by their wives. The work histories were obtained using an icon/calendar-based questionnaire that was designed to facilitate recall for migrant farmworkers, who typically have complex work histories.


RESULTS
The work histories provided by proxy respondents contained 32% fewer jobs and accounted for 24% fewer years than the self-reported histories. Correlations for lifetime duration of employment in different types of jobs were moderate to good for general agricultural jobs in Washington (0.70) and apple-related jobs (0.65), which were held by virtually all of the farmworkers; correlations were moderate to poor for less common jobs and for specific types of tasks. Agreement was better after marriage than before, and for jobs held in the current year compared to other time frames. Overall, the ability of the spouses to provide occupational histories for farmworkers was within the range observed in studies involving other occupations and industries.


CONCLUSIONS
In studies involving farmworkers, when study subjects cannot be interviewed, spouses can provide useful information on occupational histories. However, the information should be used only for more generalized exposure assessments; it is most appropriate for estimating cumulative duration of agricultural work, or recent work, by place or for common crops.
Colt
J S
JS
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland 20892-7240, USA. coltj@mail.nih.gov
Engel
L S
LS
Keifer
M C
MC
Thompson
M L
ML
Zahm
S H
SH
D000328:Adult; D000368:Aged; D000383:Agriculture / Q000706:statistics & numerical data*; D004651:Employment / Q000706:statistics & numerical data*; D004812:Epidemiologic Methods; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D019727:Proxy; D012680:Sensitivity and Specificity; D018454:Spouses; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D014171:Transients and Migrants / Q000706:statistics & numerical data*; D014861:Washington