Metabolic syndrome biomarkers have been validated as predictors of World Trade Center-related lung injury (WTC-LI) in a large population of exposed firefighters, according to a study published in CHEST.

This study included a baseline cohort of firefighters with normal forced expiratory volume in 1 second (FEV₁) before September 11, 2001 (9/11), who had been exposed to the WTC site (N=7487), and had serum tested prior to July 24, 2002. In longitudinal fashion, the participants were followed until August 1, 2017. Cases of WTC-LI were defined by FEV1 less than the lower limit of normal (LLN) at least twice during this time period. Diagnosis of metabolic syndrome was based on NCEP-ATP-III guidelines, with ≥3 criteria: systolic blood pressure (SBP) ≥130 mm Hg or diastolic blood pressure (DBP) ≥85 mm Hg, high density lipoprotein (HDL) <40 mg/dL, triglycerides ≥150 mg/dL, insulin resistance as glucose ≥100 mg/dL, or body mass index (BMI) >30 kg/m².

Metabolic syndrome-defined levels of triglycerides, HDL, SBP, DBP, and BMI were significant individual risk factors associated with developing WTC-LI. Having FEV₁<LLN at least twice was associated with high BMI, DBP, and triglycerides. A small but significant risk reduction of 1% for each additional year was associated with increasing age. Smoking increased the risk of WTC-LI by 15.2%. In addition, the most highly exposed individuals who were at the WTC site on the morning of 9/11 had 30.1% increase risk for WTC-LI vs an 18.7% increased risk if they arrived in the afternoon of 9/11 compared with the least exposed group.

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Limitations of this study included insufficient data on cigarette smoking history (only self-reported smoking status), no pack-year history, and no secondhand smoke exposure data available.

To the authors’ knowledge, this was the first study to validate biomarkers of metabolic syndrome to predict WTC-LI, which is in contrast to other studies that suggest the opposite: possible lung injury predicts incident metabolic syndrome. This was also longest longitudinal study to demonstrate that metabolic syndrome risk factors may place patients at a higher risk for FEV1 loss than either particulate matter exposure or smoking.

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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 [published online March 2, 2019]. CHEST. doi:10.1016/j.chest.2019.02.019

This article originally appeared on Pulmonology Advisor