The Link between Stress and Cardiac Outcomes in Firefighters

Heart disease (HD) is the leading cause of death and disability; in 2019, cardiovascular disease alone killed 18.6 million people worldwide. Stress is widely cited as a factor contributing to the development of HD and fatal cardiac events. Firefighters (FFs) may have an incremental risk of developing HD due to occupational stress, physical exertion, shift schedules, and toxic exposures. Past studies indicate that FFs have elevated cardiac mortality while on duty, despite starting their career in good health. In this chapter, we consider the quality of evidence and the extent to which it has supported the causation of FF work as an independent risk factor for HD using The Bradford Hill Criteria for causation. We searched electronic databases (onset to 2022) and hand-searched them to locate animal and human studies that investigated the causation pathway of stress and HD. These studies were synthesized to create a causal hypothesis of the stress–HD relationship among FFs and to summarize the existing causal hypothesis among the general population. We discuss potential confounders, critical appraisal, and critical analysis of causation, including the importance of considering these factors. There is minimal literature examining the stress–HD relationship among FFs, resulting in weak and uncertain evidence and the inability to perform a causal analysis. Among animal and human studies, there is convincing evidence for a causal relationship. To determine the relationship among FFs, we suggest future studies should focus on longitudinal designs among diverse samples with varying methods and locations and measure HD directly.