A Piecewise Exponential Change Point Model to Estimate the Duration of the Effect of World Trade Center Exposure on Incident Diagnoses of Chronic Rhinosinusitis

• Activity Number: 554
• Type: Contributed
• Date/Time: Wednesday, August 12, 2015 : 10:30 AM to 12:20 PM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Charles B. Hall and Jessica Weakley* and Xiaoxue Liu and Rachel Zeig-Owens and Mayris Webber and David Prezant
• Companies: Albert Einstein College of Medicine and Montefiore Medical Center and Montefiore Medical Center and Montefiore Medical Center and Montefiore Medical Center and Fire Department of the City of New York
• Keywords: iIncidence models ; change points ; survival analysis ; disaster epidemiology

Abstract

Adverse upper respiratory effects of exposure to the World Trade Center (WTC) disaster site have been previously reported. We model how the effect of WTC exposure on physician-diagnosed chronic rhinosinusitis in firefighters changed over 13 years (9/11/2001-9/10/2014) using incidence models with change points. Exposure was grouped by time of arrival at the WTC site as follows: (high) morning 9/11/2001 (n=1,631); (moderate) afternoon 9/11/2001 or 9/12/2001 (n=7,082); or (low) 9/13-24/2001 (n=1,209). Piecewise exponential survival models were used to estimate incidences by exposure group, with change points in the relative incidences estimated by maximum likelihood. Due to a programmatic change, incidences dramatically increased in all exposure groups starting in 2007. We observed only one change point during the study period, 3/2012, with relative incidence (high vs. low exposure) of 1.99 (95% CI 1.65-2.39) prior to 3/2012 and no significant difference in relative incidences after 3/2012. These results show that change point models are a practical method for evaluating change(s) in exposure/response relationships over time.