Measuring the effects of air pollution in patients with severe emphysema: The national emphysema treatment trial (NETT)

Background: Emphysema is a chronic obstructive pulmonary disease that affects approximately 5 million people in the US. For patients with severe emphysema, few effective treatment options exist, however, the recent adoption of lung volume reduction surgery (LVRS) is considered a promising alternative to traditional therapy. The national emphysema treatment trial (NETT) was a randomized controlled trial designed to assess the efficacy of LVRS and medical therapy versus standard medical management in patients with severe emphysema. Results from the trial showed that patients receiving the surgery fared better in terms of survival and morbidity. To date, the potential effects of air pollution on the health of these patients have not been evaluated. Methods: NETT trial data and kriged daily values of fine particulate matter (PM2.5) and ozone from the EPA air quality systems database were used to assess the effects of air pollution on the respiratory morbidity and mortality of NETT participants. Mixed linear models were employed to examine both the short- and long-term health effects of ozone and PM2.5. In addition, frailty survival models were constructed to investigate how post-operative mortality was impacted as a result of air pollutant exposures. Results: Preliminary results indicate that NETT patients experienced varying levels of exposure to ozone and PM2.5. We hypothesize that MT patients exposed to higher levels of pollutants (both chronically and acutely) will report more incidents of adverse respiratory outcomes than LVRS patients. Moreover, LVRS patients exposed to higher levels of pollution will be at increased risk for post-operative mortality.