Document Type


Date of Degree

Spring 2017

Degree Name

PhD (Doctor of Philosophy)

Degree In

Translational Biomedicine

First Advisor

Peek-Asa, Corinne

First Committee Member

Ahmed, Azeemuddin

Second Committee Member

Cavanaugh, Joseph E.

Third Committee Member

Ramirez, Marizen R.

Fourth Committee Member

Torner, James C.


Agriculture is a hazardous industry with high rates of occupational industry. Due to a variety of occupation-related factors, farmers may also be at risk for delays in reaching trauma services. Though the state of Iowa has a comprehensive trauma system implemented to provide an efficient response to traumatic injuries, it is unknown how farmers fare in this system. The aims of this study were to determine if the use of emergency medical services (EMS), the occurrence of interfacility transfers, the time to definitive care in severely injured patients, and the length of prehospital intervals for those using EMS differs between farmers and other workers.

A population-based, retrospective observational study was performed using data from the Iowa State Trauma Registry for the years 2005-2011. Eligible entries included adults (≥15 year old) sustaining an occupational injury within the state of Iowa and treated in an Iowa trauma center. Multiple imputation was performed to replace values for missing covariates. Logistic regression modeling was performed to examine the use of EMS and the occurrence of interfacility transfers among farmers compared to non-farmers. Survival analysis was performed to determine the time to definitive care for severely injured farmers compared to severely injured non-farmers; similarly, a survival-based multi-state model was performed to compare the prehospital time intervals for farmers to non-farmers among EMS users.

The study demonstrated that the likelihood of EMS use was dependent on injury severity. For lower severity injuries, farmers were less likely to use EMS, but there was no difference in EMS use for high severity injuries. The occurrence of interfacility transfers was also dependent on injury severity as well as rurality. Farmers tended to be less likely to receive an interfacility transfer in more rural areas; in large town and urban areas, farmers tended to be more likely to receive an interfacility transfer, particularly for moderate and severe injuries. These trends were slightly stronger for EMS non-users than EMS users; however, the results did not reach statistical significance for most levels. The median time to definitive care for farmers was nearly an hour longer for farmers compared to non-farmers (1h48m vs. 2h46m, respectively). In the survival analysis, time to definitive care for severely injured farmers compared to severely injured non-farmers was found to be time-dependent, and was only significant in the first hour after injury. When the prehospital time intervals for farmers using EMS (included all severities) were compared to non-farmers, farmers took longer to complete the discovery, response, and transport intervals; the scene interval was the only interval that did not reach statistical significance.

The results obtained from this study provide useful information about the operation of the Iowa State Trauma System. While EMS use was lower for minor injuries, farmers with severe injuries had no significant difference in EMS use compared to non-farmers, suggesting comparable access. Likewise, the probability of transfer was only higher in specific instances when the patient did not use EMS. However, the fact that both time to definitive care and several prehospital intervals were longer suggest that occupation-specific factors may contribute to delay. Further research is needed to identify these barriers and develop new strategies to improve the response to traumatic agricultural injury.

Public Abstract

Farming is very dangerous work. This is worsened by the fact that farmers may face delays in receiving medical treatment after an injury. The state of Iowa has a trauma system that is designed to respond to emergencies, but it is unknown whether it functions adequately for farmers.

Data about injuries treated in Iowa hospitals are submitted to a state registry; this data was used to compare features of the trauma response to work-related injuries in farmers to that of other workers. In particular, the study examined whether farmers used an ambulance, whether farmers were as likely to need transport to a second hospital for additional treatment, and how long it took farmers to complete the process of getting to care.

The most severely injured farmers were just as likely to use an ambulance as other workers and, in most cases, were not more likely to need treatment at a second hospital. These findings suggest that the trauma system is similarly able to deliver farmers to a hospital with the appropriate capabilities. However, it took longer for the ambulance to be notified that the farmer had been injured, for the ambulance to reach the farmer, for the ambulance to drive to the hospital, and, overall, for the farmer to reach their final destination. Further research is needed to determine the cause, the effects, and possible solutions for these delays.


agriculture, definitive care, emergency medical services, prehospital care, transfer, trauma


xii, 100 pages


Includes bibliographical references (pages 92-100).


Copyright © 2017 Amanda Rachel Swanton