Ambient Air Pollution and Adverse Waitlist Events among Lung Transplant Candidates

Background. Air pollution is associated with cardiopulmonary disease and death in the general population. Fine particulate matter (PM_2.5) is particularly harmful due to its ability to penetrate into areas of gas exchange within the lungs. Persons with advanced lung disease are believed to be particularly susceptible to PM_2.5exposure, but only a few studies have examined the effect of exposure on this population. Here we investigate the association between PM_2.5exposure and adverse waitlist events among lung transplant (LT) candidates. Methods. US registry data were used to identify LT candidates listed between January 1, 2010 and December 31, 2016. Annual PM_2.5concentration at year of listing was estimated for each candidate's ZIP Code using National Aeronautics and Space Administration's (NASA) Socioeconomic Data and Applications Center Global Annual PM_2.5Grids. We estimated crude and adjusted hazard ratios for adverse waitlist events, defined as death or removal, using Cox proportional hazards regression. Results. Of the 15 075 included candidates, median age at listing was 60, 43.8% were female individuals, and 81.7% were non-Hispanic White. Median ZIP Code PM_2.5concentration was 9.06 µg/m³. When compared with those living in ZIP Codes with lower PM_2.5exposure (PM_2.5<10.53 µg/m³), candidates in ZIP Codes in the highest quartile of PM_2.5exposure (≥10.53 µg/m³) had 1.14-fold (95% confidence interval, 1.04-1.25) risk of adverse waitlist events. The result remained significant after adjusting for demographics, education, insurance, smoking, lung allocation score, body mass index, and blood type (hazard ratio, 1.17; 95% confidence interval, 1.07-1.29). Conclusions. Elevated ambient PM_2.5concentration was associated with adverse waitlist events among LT candidates. These findings highlight the impact of air pollution on clinical outcomes in this critically ill population.