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' occupation al histories. The quality of proxy-reported information in occupational his tories has never been evaluated for migrant farmworkers. Methods We compared occupational histories self-reported by 31 farmworkers with those reported by their wives. Vie 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% fewe r 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) a nd apple-related jobs (0.65), which were held by virtually all of the farmw orkers; correlations were moderate to poor for less common jobs and for spe cific types of tasks. Agreement was better after marriage than before, and for jobs held in the current year compared to other time frames. Overall, t he ability of the spouses to provide occupational histories for farmworkers was within the range observed in studies involving other occupations and i ndustries. Conclusions In studies involving farmworkers, when study subjects cannot be interviewed, spouses cat? provide useful information on occupational histo ries. However, the information should be used only for more generalized exp osure assessments; it is most appropriate for estimating cumulative duratio n of agricultural work, or recent work, by place or for common crops. (C) 2 001 Wiley-Liss, Inc.