Comparison of the extent and progression of respiratory and cardiovascular disease in World Trade Center responders to lung screening participants

Responders to the World Trade Center (WTC) site in the aftermath of the 9/11 attacks were exposed to toxic dust, which has been linked to increased risk of respiratory and cardiovascular disease. The respiratory and cardiovascular effects of WTC dust exposure have been studied using pulmonary function tests and the number of cardiovascular events, but computed tomography (CT) scans provide an opportunity to see the early structural changes in the lungs and cardiovascular system before clinical symptoms appear. CT scans are used in the screening and evaluation of respiratory diseases such as lung cancer, interstitial lung disease, and chronic obstructive pulmonary disease, and to visualize coronary arteries and quantify the amount of coronary artery calcifications; in fact, it is possible to detect multiple diseases from a single chest CT scan. While manual evaluation by a radiologist is often the gold standard, automated image analysis tools can quickly and accurately quantify these diseases.

We identified non-contrast chest CT scans from members of the World Trade Center General Responders Cohort (WTC GRC) with slice thickness of 2.5 mm or less. We used the open-source Chest Imaging Platform software to compute measures of emphysema and interstitial lung disease and research software from Cornell University to compute measures of pulmonary hypertension and coronary artery calcification. We identified a sex, age (within 5 years), smoking status, one or more CT scans, and follow-up time -matched cohort of participants enrolled in the lung screening program at Mount Sinai. We compared disease measures from the WTC GRC group to the lung screening group to assess whether there was a difference in the extent and progression of disease.

There were 4909 chest CT images of members of the WTC GRC that met our image quality criteria. There were 3855 members of the GRC for which we could obtain both chest CT images and clinical data. Of these, there were 2284 members for which we could obtain pulmonary disease measurements on at least one scan, 1246 members for which we could calculate cardiac measurements. The matched controls from the lung screening cohort consisted of 557 participants with 1122 chest CT images that met our image quality criteria and for which we obtained all four disease measures.

We compared members of the WTC GRC with matched participants from the lung screening program. One of the key findings is that after a median time of 11-13 years after 9/11, the WTC GRC group exhibited higher burdens of coronary artery calcification, emphysema, and interstitial lung disease compared with a matched control group of lung screening participants. This supports the continued surveillance of WTC responders.