Metabolic syndrome is useful for predicting future lung injury in a cohort of individuals who were exposed to particulate matter from the World Trade Center (WTC) collapse, according to study results published in CHEST.
Metabolic syndrome is a constellation of risk factors associated with end-organ disease and diagnosis is made by having ≥3 of the following: abdominal obesity, insulin resistance, hypertriglyceridemia, low high-density lipoprotein levels, and hypertension. Metabolic syndrome and particulate matter exposure are known independent risk factors for respiratory dysfunction, obstructive lung disease, and cardiovascular disease.
Researchers previously conducted a pilot study in a cohort of firefighters who were nonsmoking, had symptoms, and were exposed to the WTC and found that metabolic syndrome biomarkers predicted WTC lung injury. The researchers then conducted an intracohort validation of metabolic syndrome as a predictor of WTC lung injury in a cohort exposed to particulate matter from the WTC that has been followed longitudinally for 16 years. They evaluated the results of 98,221 pulmonary function tests in 9566 rescue and recovery workers who had normal forced expiratory volume in 1 second (FEV1) before 9/11 and who had serum drawn before site closure on July 24, 2002 (n=7487).
Patients with WTC lung injury (n=1208) were identified if they had ≥2 measured instances of FEV1 less than the lower limit of normal. The researchers found that these patients were more likely to smoke, have a high-intensity exposure, and have metabolic syndrome. There was a significant exposure dose response and individuals most highly exposed had a 30.1% increased risk of developing WTC lung injury, having ≥3 metabolic syndrome criteria increased the risk by 55.7%, and smoking increased the risk by 15.2%.
Among the study limitations, the researchers noted that smoking status was self-reported (no pack-year history or secondhand smoke data were available), patients and controls had significantly different FEV1 measurements before 9/11, and there was a lack of biomarker assessment (eg, amylin and leptin).
“We validated the usefulness of [metabolic syndrome] to predict future WTC [lung injury] in a larger population of individuals who were exposed.”
Kwon S, Crowley G, Caraher EJ, et al. Validation of predictive metabolic syndrome biomarkers of World Trade Center lung injury: a 16-year longitudinal study. CHEST. 2019;156(3):486-496.