The respiratory pyramid: From symptoms to disease in world trade center exposed firefighters

Justin K. Niles, Mayris P. Webber, Hillel W. Cohen, Charles B. Hall, Rachel Zeig-Owens, Fen Ye, Michelle S. Glaser, Jessica Weakley, Michael D. Weiden, Thomas K. Aldrich, Anna Nolan, Lara Glass, Kerry J. Kelly, David J. Prezant

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Background: This study utilizes a four-level pyramid framework to understand the relationship between symptom reports and/or abnormal pulmonary function and diagnoses of airway diseases (AD), including asthma, recurrent bronchitis and COPD/emphysema in WTC-exposed firefighters. We compare the distribution of pyramid levels at two time-points: by 9/11/2005 and by 9/11/2010. Methods: We studied 6,931 WTC-exposed FDNY firefighters who completed a monitoring exam during the early period and at least two additional follow-up exams 9/11/2005-9/11/2010. Results: By 9/11/2005 the pyramid structure was as follows: 4,039 (58.3%) in Level 1, no respiratory evaluation or treatment; 1,608 (23.2%) in Level 2, evaluation or treatment without AD diagnosis; 1,005 (14.5%) in Level 3, a single AD diagnosis (asthma, emphysema/COPD, or recurrent bronchitis); 279 (4.0%) in Level 4, asthma and another AD. By 9/11/2010, the pyramid distribution changed considerably, with Level 1 decreasing to 2,612 (37.7% of the cohort), and Levels 3 (N=1,530) and 4 (N=796) increasing to 22.1% and 11.5% of the cohort, respectively. Symptoms, spirometry measurements and healthcare utilization were associated with higher pyramid levels. Conclusions: Respiratory diagnoses, even four years after a major inhalation event, are not the only drivers of future healthcare utilization. Symptoms and abnormal FEV-1 values must also be considered if clinicians and healthcare administrators are to accurately anticipate future treatment needs, years after initial exposure. Am. J. Ind. Med. 56:870-880, 2013.

Original languageEnglish (US)
Pages (from-to)870-880
Number of pages11
JournalAmerican Journal of Industrial Medicine
Issue number8
StatePublished - Aug 2013


  • Asthma
  • Pulmonary function
  • Treatment outcomes
  • World Trade Center

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health


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