The health effects of firefighting long have been of research interest. However, a review of previous studies revealed inconclusive results regarding the effects of firefighting on the risk of developing and dying from specific diseases, including respiratory disease, cardiovascular disease and cancer.

Consequently, it was decided to conduct a study to examine the causes of death for a cohort of Indianapolis firefighters, excluding line-of-duty deaths (LODDs), to determine whether excessive cause-specific mortality existed. It is important to identify the most-common causes of death among firefighters to determine whether the cause-specific death rates are greater in firefighters compared to a similar age- and-gender-adjusted population, in order to implement appropriate programs to prevent or reduce contributing disease risk factors.

Study Methodology

Researchers at the Indiana University Bowen Research Center developed a dataset containing information on 1,126 full-time, career firefighters, employed by the IFD for at least one year and who died between 1910 and 2006. This initial dataset included active firefighters who died in the line of duty, those who did not die in the line of duty, and those who died after retirement.

The dataset was sent to the Indiana State Department of Health (ISDH) to be linked with state death certificates using first and last name, middle initial, date of death, and date of birth. The ISDH successfully linked 667 cases and provided the International Classification of Diseases (ICD) codes (revisions 8, 9 and 10) for the underlying cause of death. There were 451 cases that could not be linked to Indiana death certificates.

The study dataset then was limited to cases where death occurred between 1970 and 2006, as the majority of unlinked cases (71.6%) died before 1970. Specific identifying data (first and last name, middle initial, date of death, and date of birth) on the remaining 94 unlinked cases of death occurring between 1979 and 2004 were sent to the National Death Index (NDI) for possible linking in their database. The NDI contains death-certificate data from deaths occurring between 1979 and 2004; therefore, any unlinked cases of firefighters in this study who died from 1970 to 1978, or from 2005 to 2006, would not be included in the NDI. Of the 94 unlinked cases, the NDI was able to link 89 cases and provided the ICD codes (revisions 9 and 10) for causes of death. These 89 linked cases were combined with the previously linked 561 cases, thereby increasing the dataset to 650 linked cases.

The 34 remaining unlinked cases were sent to the Florida Department of Health, Office of Vital Statistics for linking with deaths occurring between 1970 and 1978 and 2005–2006, as Indiana retirees were known to migrate to Florida. That office linked 13 cases and provided the ICD codes (revisions 9 and 10) for causes of death. However, of the 13 cases, five were removed from the dataset because of missing or questionable data. Consequently, the final dataset used for analysis consisted of 658 IFD firefighters.

The majority of deaths in the dataset occurred from 1979 to 1998, when ICD revision 9 codes were in use. For consistency, all ICD revision 8 and 10 codes in the dataset were recoded to ICD revision 9 codes.

Proportionate mortality ratios (PMRs) were calculated by dividing the percentage of all deaths for a specific cause among the firefighter group by the percentage of all deaths for that same cause among white males in the U.S. White males were used as the comparison group because very few firefighters during the study period were females or non-white. P-values less than 0.05 were considered statistically significant.

The results of this study may not be applicable to all firefighters who died in the U.S. during the study period, because the study focused solely on one metropolitan area. Moreover, though the sample size was adequate to compare the differences in death rates for firefighters with those of the general public for common causes of death, a larger sample of firefighters would be needed to compare the differences for less-common causes of death.

Caution is further urged when interpreting the PMRs shown in these results, since many are based on small numbers of firefighter deaths. In addition, no information on personal risk factors (e.g., tobacco and alcohol use, diet, body mass index, familial tendency toward a disease) or pre-existing medical conditions was available. Adjusting for differences in these personal characteristics would remove those that are possible confounders. Also, this study did not include exposure data such as the number of fire runs, the company type, or exposure to diesel fumes for each firefighter.

Finally, the incidence rates of diseases in the firefighter population may be influenced by the “healthy-worker effect,” as firefighters tend to be more physically fit when compared to the general population. The healthy-worker effect may result in understating the mortality-disease association in those diseases with PMRs less than, but close to, 1.0. However, this study was conducted to assist with the development of wellness programs, and any disease with a PMR greater than 1.0 was considered a potential area on which to focus attention.

Study Results

The median age at death for the firefighters was 71.2 years and ranged from 23.5 to 99.7 years. The median age at appointment was 26.2 years and ranged from 17.8 to 39.6 years. Of the 615 cases with known retirement age, or age at death if not retired, the median age was 52.7 years and ranged from 21.7 to 70.7 years. The median number of years of service was 25.5 and ranged from 1.3 to 62.6. Of the 644 cases with known number of years between retirement and death, the median was 18.7 years and ranged from 0 to 54.4.

Download complete study results

The two leading causes of death, accounting for 70.4% of the total, were circulatory diseases, with 284 deaths (43.2%) and neoplasms, with 179 deaths (27.2%). The third-most-frequent cause of death was respiratory diseases, with 63 deaths (9.6%), followed by digestive diseases, with 26 deaths (4.0%).

Examining the individual ICD-9 categories revealed that ischemic heart diseases accounted for the highest number of deaths (184, 28.0%), with 105 of these cases classified as other forms of chronic ischemic heart diseases (16.0%) and 79 as acute myocardial infarction (12.0%). Malignant neoplasm of respiratory and intrathoracic organs was the second-leading cause of death (84, 12.8%), with 83 of these cases being cancer of the lung (12.6%). Chronic obstructive pulmonary disease (COPD) was the fourth highest, with 42 deaths (6.4%).

Based on the PMRs, Indianapolis firefighters of all ages had four diagnoses with mortality rates that were significantly higher as compared with U.S. white males. Firefighters were 6.5 times more likely to die of chronic disease of endocardium and other myocardial insufficiency; 2.3 times more likely to die from septicemia; 1.5 times more likely to die from chronic obstructive pulmonary diseases (COPD); and 1.2 times more likely to die from other forms of chronic ischemic heart disease. Meanwhile, IFD firefighters were significantly less likely to die from malignant neoplasms of the respiratory system (PMR=0.8); acute myocardial infarctions (PMR=0.8); all other forms of heart disease (PMR=0.6); and pneumonia (PMR=0.6).

Among firefighters under age 65, there were four diagnoses with mortality rates significantly higher for the firefighters compared with U.S. white males. IFD firefighters under age 65 were 15.7 times more likely to die of chronic disease of endocardium and other myocardial insufficiency; 1.7 times more likely to die from malignant neoplasm of the digestive organs and peritoneum; 1.7 times more likely to die from chronic liver disease and cirrhosis; and 1.6 times more likely to die from other forms of chronic ischemic heart disease. Meanwhile, firefighters under the age of 65 were significantly less likely to die from malignant neoplasm of the respiratory system (PMR=0.5); and pneumonia (PMR=0.0).

Among firefighters age 65 and older, there were four diagnoses with mortality rates significantly higher for firefighters compared with U.S. white males in the same age group. IFD firefighters were 9.5 times more likely to die of chronic disease of endocardium and other myocardial insufficiency; 2.2 times more likely to die from septicemia; 1.5 times more likely to die from malignant neoplasms of the respiratory system; and 1.5 times more likely to die from COPD. However, older firefighters were significantly less likely to die from malignant neoplasms of the digestive organs and peritoneum (PMR=0.6), diseases of the heart (PMR=0.9) — including ischemic heart disease (PMR=0.9), which includes acute myocardial infarctions (PMR=0.6) — and all other forms of heart disease (PMR=0.4).

What it All Means

The results of this study identified increased firefighter mortality rates in four specific disease categories: septicemia, other forms of chronic ischemic heart disease, chronic disease of the endocardium and other myocardial insufficiency, and chronic obstructive pulmonary disease.

However, it is noteworthy that the likelihood of death from an acute myocardial infarction, and from pneumonia and malignant neoplasms of the respiratory system were significantly less than for the comparison group. Moreover, there were no neoplasm types with excessive PMRs when examined as a total group; however, some types were higher within the specific age groups. This differs from what other studies have shown.

Previous firefighter-mortality studies were conducted to determine occupational exposure and establish that firefighters with certain diseases die at higher levels than the rest of the population. This use of those study results can be viewed as validating worker’s compensation efforts by strengthening the association between occupational environment and health.

However, in addition to contributing to the knowledge of occupation-death associations, local mortality studies can be used to design better health, wellness and prevention programs. Fire department fitness programs and worksite health-and-wellness programs should actively target those health risks that most impact the diseases that have excessive mortality. By examining PMR by age group, interventions could be developed that are targeted to those who need it the most. For example, the increased likelihood of younger firefighters dying from chronic liver disease and cirrhosis is an indicator that more probing into alcohol use and more intense counseling by providers may be in order.

The study further revealed that more than one-third of all deaths among retired or employed Indianapolis firefighters (excluding LODDs) were due to diseases of the heart. Firefighters primarily join the fire service as young or middle-aged adults; thus, tailored prevention programs should be implemented to prevent or reduce the risk factors associated with heart diseases, even though not all forms had higher PMRs. Firefighters may lessen the risk of developing ischemic heart diseases by reducing high cholesterol, high blood pressure, tobacco use, excessive alcohol use and physical inactivity, as well as by preventing or controlling diabetes.

But there are other job-related risk factors that are not fully understood and are yet to be analyzed. Job-related emotional and physical stress, along with job-related shift work and sleep deprivation, are thought to be additional cardiovascular disease risk factors. Therefore, further studies need to be conducted to better understand the additional impact of job-related risk factors, along with the development of effective programs to mitigate their effect.

While local mortality studies can be used to encourage the development of fire department wellness programs, the results of this study also should be used to assess the overall workplace conditions and external environment factors that impact an individual firefighter’s health status. Recent changes in the hiring practices and incumbent fitness standards of the fire service may magnify the healthy-worker effect, by increasing the level of required physical fitness and encouraging positive changes in individual lifestyle. These trends, along with better firefighting techniques and equipment and the improved construction and design of buildings, may affect the specific causes of death among firefighters in the future.

In conclusion, specific non-line-of-duty disease-related deaths have been found to be statistically greater in Indianapolis firefighters as compared to U.S. white males. These results underscore the need for the current and greater expansion of cardiovascular disease and other disease-specific risk-factor-reduction programs for firefighters. Analysis and characterization as to the non-traditional risk factors — such as job-related emotional and physical stress, shift work and sleep deprivation — need to be further studied.

Robert M. Saywell, Jr., is professor emeritus in the Department of Family Medicine and senior investigator in the Bowen Research Center at Indiana University. He can be contacted at 317-278-0352 or rsaywell@iupui.edu. Terrell W. Zollinger, Steven M. Moffatt, Corie Galloway, Carolyn M. Muegge and Komal Kochhar contributed to this article.

Related Stories

• Early Warning System: How CRP Tests Can Detect Heart Disease in Firefighters
• Fire Smoke Coalition Uses Grant for CO, Cyanide Education
• Better Health is Within Reach: NVFC Details Heart-Healthy Initiatives