Environmental NO2 Level is Associated with 2-Year Mortality in Patients Undergoing Peritoneal Dialysis

An ongoing issue related to global urbanization is the association of air pollution with increased incidences of morbidity and mortality. However, no in-depth study has investigated this issue focusing on peritoneal dialysis (PD) patients. Therefore, this study assessed the effects of traffic-related air pollutants and other important mortality-associated factors on 2-year mortality in PD patients. A total of 160 PD patients were recruited in this 2-year retrospective observational study. Differences in air quality were analyzed with respect to the patients' living areas. The PD patients were categorized into 2 groups according to high (n = 65) and low (n = 95) nitrogen dioxide (NO2) exposure. Demographic, hematological, nutritional, inflammatory, biochemical, air pollutants, and dialysis-related data were analyzed. Univariate and multivariate Cox regression analyses were used for 2-year mortality analysis. A total of 160 PD patients (38 men and 122 women) were enrolled. Fourteen patients (8.8%) died within 2 years; among them, the causes of death were infection (n = 10), malignancy (n = 1), and cardiovascular events (n = 3). Among the 10 patients who died from infection, 5, 4, and 1 died from pneumonia, PD-related peritonitis, and sepsis of unknown origin, respectively. All patients who died from pneumonia were living in high environmental NO2 exposure areas. Multivariate Cox regression analysis showed that age (hazard ratio [HR] 1.073, 95% confidence interval [CI] [1.013-1.137]; P = 0.017), white blood cell count (HR 1.41, 95% CI [1.116-1.781]; P = 0.004), log normalized protein nitrogen appearance (HR 0.0001, 95% CI [0-0.073]; P = 0.005), high cardiothoracic ratio (HR 14.28, 95% CI [1.778-114.706]; P = 0.012), and high environmental NO2 exposure (HR 3.776, 95% CI [1.143-12.47]; P = 0.029) were significantly associated with 2-year mortality. PD patients with high environmental NO2 exposure had a higher 2-year mortality rate than those with low exposure. Therefore, air pollution may be associated with 2-year mortality in such patients.