Visit-to-Visit FEV Variation and Mortality in New York City Fire Department Rescue and Recovery Workers Exposed to World Trade Center Collapse-Related Dust.

Forced expiratory volume in 1 second (FEV) and its longitudinal change are mortality risk factors. Visit-to-visit FEV variation is a risk factor for death in cystic fibrosis but has not been studied in other cohorts. We sought to assess whether longitudinal visit-to-visit FEV variation is a mortality risk factor in rescue and recovery workers in the Fire Department of New York who were exposed to dust related to the collapse of the World Trade Center on September 11, 2001 (9/11/2001). Linear mixed-effects regression of all post-9/11/2001 FEV measurements defined the time effect on longitudinal FEV decline (FEV slope) and its standard error (visit-to-visit FEV variation). Cox proportional hazards and logistic models adjusted for age and smoking assessed the association between FEV-related risk factors and mortality. Receiver operating characteristic area under the curve (AUC) assessed predictive model performance. Among 11,745 workers with three or more FEV measurements, 575 (4.9%) died. When all FEV-related risk factors were combined, each 5-ml/yr increase in visit-to-visit FEV variation increased mortality 2.1-fold (hazard ratio [HR] = 2.14; 95% confidence interval [CI] = 1.84-2.48); each 10% predicted reduction in the last longitudinal FEV increased mortality 15% (HR = 1.15; 95% CI, 1.09-1.21), but each 10-ml/yr longitudinal FEV decline was not associated with mortality (HR = 1.04; 95% CI, 0.99-1.10). The receiver operating characteristic AUC of a fully adjusted multivariable cumulative mortality model was 0.82 (95% CI, 0.80-0.84); for unadjusted visit-to-visit FEV variation, the AUC was 0.80 (95% CI, 0.78-0.82); for last longitudinal FEV, the AUC was 0.61 (95% CI, 0.59-0.64); and for longitudinal FEV decline, the AUC was 0.58 (95% CI, 0.56-0.61). In the ratio of participants with high exposure/total number of participants (1,988/11,745; 16.9%), among patients with high exposure, defined as arrival at the World Trade Center site before noon on 9/11/2001, the risk of high visit-to-visit FEV variation (top quartile, ⩾10.35 ml/yr) increased 25% (odds ratio = 1.25; 95% CI, 1.12-1.40). Visit-to-visit FEV variation is a mortality risk factor in rescue and recovery workers in the Fire Department of New York City, with greater accuracy for predicting cumulative mortality than either last longitudinal FEV or longitudinal FEV decline. Further investigation in other cohorts is needed to assess the generalizability of this rarely studied mortality risk factor.