Normal Lung Function and Mortality in World Trade Center Responders and National Health and Nutrition Examination...

Rationale: Low FEV₁ is a biomarker of increased mortality. The association of normal lung function and mortality is not well described. Objectives: To evaluate the FEV₁-mortality association among participants with normal lung function. Methods: A total of 10,999 Fire Department of the City of New York (FDNY) responders and 10,901 Third National Health and Nutrition Examination Survey (NHANES III) participants, aged 18-65 years with FEV₁ ⩾80% predicted, were analyzed, with FEV₁ percent predicted calculated using Global Lung Function Initiative Global race-neutral reference equations. Mortality data were obtained from linkages to the National Death Index. Cox proportional hazards models estimated the association between FEV₁ and all-cause mortality, controlling for age, sex, race/ethnicity, smoking history, and, for FDNY, work assignment. Cohorts were followed for a maximum of 20.3 years. Measurements and Main Results: We observed 504 deaths (4.6%) of 10,999 for FDNY and 1,237 deaths (9.4% [weighted]) of 10,901 for NHANES III. Relative to FEV₁ ⩾120% predicted, mortality was significantly higher for FEV₁ 100-109%, 90-99%, and 80-89% predicted in the FDNY cohort. In the NHANES III cohort, mortality was significantly higher for FEV₁ 90-99% and 80-89% predicted. Each 10% higher predicted FEV₁ was associated with 15% (hazard ratio, 0.85; 95% confidence interval, 0.80-0.91) and 23% (hazard ratio, 0.77; 95% confidence interval, 0.71-0.84) lower mortality for FDNY and NHANES III, respectively. Conclusions: In both cohorts, higher FEV₁ is associated with lower mortality, suggesting higher FEV₁ is a biomarker of better health. These findings demonstrate that a single cross-sectional measurement of FEV₁ is predictive of mortality over two decades, even when FEV₁ is in the normal range.