Longitudinal pulmonary function in newly hired, non-World Trade Center-exposed fire department City of New York firefighters: the first 5 years

Abstract

Background: Few longitudinal studies characterize firefighters’ pulmonary function. We sought to determine whether firefighters have excessive FEV(1) decline rates compared with control subjects.

Methods: We examined serial measurements of FEV(1) from about 6 months prehire to about 5 years posthire in newly hired male, never smoking, non-Hispanic black and white firefighters, hired between 2003 and 2006, without prior respiratory disease or World Trade Center exposure. Similarly defined Emergency Medical Service (EMS) workers served as control subjects.

Results: Through June 30, 2011, 940 firefighters (82%) and 97 EMS workers (72%) who met study criteria had four or more acceptable posthire spirometries. Prehire FEV(1) % averaged higher for firefighters than EMS workers (99% vs 95%), reflecting more stringent job entry criteria. FEV(1) (adjusted for baseline age and height) declined by an average of 45 mL/y both for firefighters and EMS workers, with Fire 2 EMS decline rate differences averaging 0.2 mL/y (CI, 2 9.2 to 9.6). Four percent of each group had FEV(1) less than the lower limit of normal before hire, increasing to 7% for firefighters and 17.5% for EMS workers, but similar percentages of both groups had adjusted FEV(1) decline rates 10%. Mixed effects modeling showed a significant influence of weight gain but not baseline weight: FEV(1) declined by about 8 mL/kg gained for both groups. Adjusting for weight change, FEV(1) decline averaged 38 mL/y for firefighters and 34 mL/y for EMS workers.

Conclusions: During the first 5 years of duty, firefighters do not show greater longitudinal FEV(1) decline than EMS control subjects, and fewer of them develop abnormal lung function. Weight gain is associated with a small loss of lung function, of questionable clinical relevance in this fit and active population.

Figure 1.

Flow diagram of the study population. Of the 1,169 never smoking firefighters and 134 never smoking EMS workers in the cohort, one firefighter and no EMS workers died; 13 firefighters (1%) and 29 EMS workers (22%) resigned, were terminated, or retired (none on respiratory disability); and 155 firefighters (13%) and five EMS workers (4%) were not yet due for their fourth posthire spirometry. Only 60 firefighters (5%) and two EMS workers (1%) were overdue for their fourth posthire spirometry. EMS = Emergency Medical Service; FIRE = firefighters.

Figure 2.

Average unadjusted FEV₁ by visit for firefighters and EMS workers. Data are mean ± SEM for the same 940 firefighters and 97 EMS workers at each time point. Mean data and SEMs are also shown for time relative to the date of hire. (SEMs are too small to be separable from the means for firefighters). See Figure 1 legend for expansion of abbreviations.

Figure 3.

Matched pair analysis for 42 firefighters and 42 EMS workers, matched by age, race, height, baseline FEV₁, baseline weight, and average percentage of weight change per year. Data are mean ± SEM. See Figure 1 legend for expansion of abbreviations.

Figure 4.

A, The percentage of each group (firefighters and EMS workers) whose FEV₁ fell below the LLN. B, Percentage of firefighters and EMS workers who showed excessive decline in FEV₁ (≥ 10% decline in FEV₁ vs baseline, after correction for the average decline of FEV₁ for EMS workers cohort and firefighters cohort). LLN = lower limit of normal. See Figure 1 legend for expansion of other abbreviations.