Farm health surveillance in the Marshfield Epidemiologic Study Area: a pilot study

Surveillance of agricultural work-related illness and non-fatal injuries is limited and considered to be a major gap in prevention and policy-making capacity. This pilot study evaluated the utility of the Marshfield Epidemiologic Study Area (MESA) and its farm residency cohort to identify and monitor potential priorities for prevention and control. MESA is a defined geographic region that serves as a resource for conducting population-based health research. Nearly all of the residents receive their health care from the Marshfield Clinic and affiliated hospitals, providing archived electronic medical information to characterize past and present diagnoses. Based on scientific literature and national research priorities, five broad health issues (injuries, back problems, hearing loss, respiratory conditions, and dermatologic conditions) were selected. To estimate age-specific and age-adjusted incidence and prevalence, we followed a fixed cohort of 1995 MESA residents through 2002. Standardized incidence ratios and standardized prevalence ratios were also estimated to quantify the potential impact of farm residency. Linking MESA, its farm residency cohort, and the clinic's data archives allowed successful identification of significant associations with agricultural exposure for a few conditions and subconditions related to consensus priorities in agricultural health, particularly among men. These included extrinsic alveolitis, organic dust toxic syndrome, back pain, osteoarthrosis, and certain injuries. However, the system was generally not able to demonstrate strong influence of farm residency on disease occurrence for many conditions specifically selected for their likely capacity to show such influence. Future surveillance systems should supplement clinical data with other sources of information on health events and should be adequately powered to focus on narrower ranges of health conditions.