Estimating the Time Interval Between Exposure to the World Trade Center Disaster and Incident Diagnoses of Obstructive Airway Disease

Abstract

Respiratory disorders are associated with occupational and environmental exposures. The latency period between exposure and disease onset remains uncertain. The World Trade Center (WTC) disaster presents a unique opportunity to describe the latency period for obstructive airway disease (OAD) diagnoses. This prospective cohort study of New York City firefighters compared the timing and incidence of physician-diagnosed OAD relative to WTC exposure. Exposure was categorized by WTC arrival time as high (on the morning of September 11, 2001), moderate (after noon on September 11, 2001, or on September 12, 2001), or low (during September 13–24, 2001). We modeled relative rates and 95% confidence intervals of OAD incidence by exposure over the first 5 years after September 11, 2001, estimating the times of change in the relative rate with change point models. We observed a change point at 15 months after September 11, 2001. Before 15 months, the relative rate for the high- versus low-exposure group was 3.96 (95% confidence interval: 2.51, 6.26) and thereafter, it was 1.76 (95% confidence interval: 1.26, 2.46). Incident OAD was associated with WTC exposure for at least 5 years after September 11, 2001. There were higher rates of new-onset OAD among the high-exposure group during the first 15 months and, to a lesser extent, throughout follow-up. This difference in relative rate by exposure occurred despite full and free access to health care for all WTC-exposed firefighters, demonstrating the persistence of WTC-associated OAD risk.

FDNY and 9/11: Clinical services and health outcomes in World Trade Center‐exposed firefighters and EMS workers from 2001 to 2016

“…In 2011, we showed that early arrival time at the WTC‐site was significantly associated with scoring at high risk for obstructive sleep apnea (OSA) using an adapted Berlin screening survey [Webber et al, ]. In a later study, we confirmed that 89% of 636 participants who scored high risk for OSA had polysomnogram‐confirmed OSA [Glaser et al, ]. We also found that FDNY rescue/recovery workers who arrived at the WTC during the morning of 9/11 had almost twice the odds (OR: 1.91; 95%CI: 1.15–3.17) of polysomnogram‐confirmed OSA than those with lower levels of WTC‐exposure.…”

The Duration of an Exposure Response Gradient between Incident Obstructive Airways Disease and Work at the World Trade Center Site: 2001-2011

“…The change points are the times that the relative rates change (increase or decrease) during the follow-up period; these change points are estimated from the data using profile likelihood. 21 , 22 , 23 A change point after which relative incidences did not differ significantly (p<0.05) from one would show that the exposure-response relationship between WTC exposure intensity and incident OAD was limited to the period prior to the change point. All models included as covariates: age on 9/11/2001, retirement status, if applicable, as a time-dependent predictor, and self-reported smoking status (ever vs. never) as of the last completed questionnaire.…”

“…Details of the methodological approach have been reported previously. 21 Briefly, we used piecewise exponential survival models with change points to estimate relative rates across the three exposure groups during follow up (9/11/2001 to 9/10/2011). Piecewise exponential survival models are similar to Cox regression models, but with baseline hazards that are allowed to change at a fixed number of time intervals rather than with every new event.…”

The Effect of World Trade Center Exposure on the Timing of Diagnoses of Obstructive Airway Disease, Chronic Rhinosinusitis, and Gastroesophageal Reflux Disease

“…We have previously reported that FDNY WTC rescue/recovery workers were more frequently diagnosed with OAD than CRS in the months and years after exposure, but that over time, diagnoses of CRS increased ( 2 , 3 , 15 ). Similarly, about 6 years postexposure, GERD diagnoses, which had the lowest immediate post-9/11 incidence of these aerodigestive conditions, started to increase (unpublished data).…”