Long-term Cardiovascular Disease Risk Among Firefighters After the World Trade Center Disaster

Abstract

Importance: Published studies examining the association between World Trade Center (WTC) exposure on and after September 11, 2001, and longer-term cardiovascular disease (CVD) outcomes have reported mixed findings.

Objective: To assess whether WTC exposure was associated with elevated CVD risk in Fire Department of the City of New York (FDNY) firefighters.

Design, settings, and participants: In this cohort study, the association between WTC exposure and the risk of CVD was assessed between September 11, 2001, and December 31, 2017, in FDNY male firefighters. Multivariable Cox regression analyses were used to estimate CVD risk in association with 2 measures of WTC exposure: arrival time to the WTC site and duration of work at the WTC site. Data analyses were conducted from May 1, 2018, to March 8, 2019.

Main outcomes and measures: The primary CVD outcome included myocardial infarction, stroke, unstable angina, coronary artery surgery or angioplasty, or CVD death. The secondary outcome (all CVD) included all primary outcome events or any of the following: transient ischemic attack; stable angina, defined as either use of angina medication or cardiac catheterization without intervention; cardiomyopathy; and other CVD (aortic aneurysm, peripheral arterial vascular intervention, and carotid artery surgery).

Results: There were 489 primary outcome events among 9796 male firefighters (mean [SD] age on September 11, 2001, was 40.3 [7.4] years and 7210 individuals [73.6%] were never smokers). Age-adjusted incident rates of CVD were higher for firefighters with greater WTC exposure. The multivariable adjusted hazard ratio (HR) for the primary CVD outcome was 1.44 (95% CI, 1.09-1.90) for the earliest arrival group compared with those who arrived later. Similarly, those who worked at the WTC site for 6 or more months vs those who worked less time at the site were more likely to have a CVD event (HR, 1.30; 95% CI, 1.05-1.60). Well-established CVD risk factors, including hypertension (HR, 1.41; 95% CI, 1.10-1.80), hypercholesterolemia (HR, 1.56; 95% CI, 1.28-1.91), diabetes (HR, 1.99; 95% CI, 1.33-2.98), and smoking (current: HR, 2.13; 95% CI, 1.68-2.70; former: HR, 1.55; 95% CI, 1.23-1.95), were significantly associated with CVD in the multivariable models. Analyses with the all-CVD outcome were similar.

Conclusions and relevance: The findings of the study suggest a significant association between greater WTC exposure and long-term CVD risk. The findings appear to reinforce the importance of long-term monitoring of the health of survivors of disasters.

Figure 1.. Cardiovascular Disease (CVD) Outcomes by Year

All CVD outcomes data include CVD events in primary CVD outcome. ^aFrom September 11 to December 31, 2001.

Figure 2.. Age-Adjusted Cardiovascular Disease (CVD) Incidence Rates

Incidence of CVD by arrival group (A) and duration group (B). The arrival groups are defined in the WTC Exposure subsection of the Methods section. Error bars indicate 95% CIs.

Figure 3.. Primary Cardiovascular Disease Outcome Estimated Using the Fully Adjusted Cox Proportional Hazard Models With Arrival Group

9/11 indicates September 11, 2001; 9/12-9/24, between September 12 and September 24. Body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) category 1 indicates underweight or normal weight (BMI, ≤24.9); category 2, preobesity (25.0-29.9); category 3, obesity class I (30.0-34.9); category 4, obesity class II (35.0-39.9); and category 5, obesity class III (≥40.0). HR indicates hazard ratio; PTSD, posttraumatic stress disorder. Error bars indicate 95% CIs.

Figure 4.. Primary Cardiovascular Disease Outcome Estimated Using the Fully Adjusted Cox Proportional Hazard Models With Duration Group

Body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) category 1 indicates underweight or normal weight (BMI, ≤24.9); category 2, preobesity (25.0-29.9); category 3, obesity class I (30.0-34.9); category 4, obesity class II (35.0-39.9); and category 5, obesity class III (≥40.0). HR indicates hazard ratio; PTSD, posttraumatic stress disorder. Error bars indicate 95% CIs.