The association between particulate matter 2.5 and hospitalization and mortality rates of heart failure: The CAPACITY study

BACKGROUND: Considering the high concentrations of pollutants in large cities of Iran and the high prevalence of heart failure (HF) among Iranians, especially with increasing life expectancy, this study investigated the relationship between airborne contaminants with a diameter < 2.5 µm or particulate matter 2.5 (PM2.5) and hospitalization and mortality in patients with HF in Isfahan, Iran, during 2011. METHODS: This ecological study was carried out on a part of data from the CAPACITY study. A total of 275 patients with HF were randomly selected from 840 subjects with International Statistical Classification of Diseases, 10th Revision (ICD-10) diagnosis code I50 in the CAPACITY study. Patients’ records were evaluated and their clinical characteristics, disease history, and laboratory and echocardiographic findings were extracted. Air pollution and climatic data were extracted from the CAPACITY study. Poisson regression was used in crude and adjusted models to evaluate the association between PM2.5 and study outcomes. All analyses were performed using crude models and models adjusted for temperature, dew point, and wind speed. RESULTS: 54.9% (n = 151) were men with mean age of 70.4 ± 13.7 years. While most patients (85.8%) were discharged after recovery, 14.2% of the patients died in the hospital. Blood glucose, heart rate, and ejection fraction (EF) were significantly higher on unhealthy days than normal days. Regression analysis revealed no significant relationships between hospitalization and mortality rates and PM2.5 concentrations on healthy days, unhealthy days for sensitive people, and unhealthy days. CONCLUSION: The model used in our study revealed no significant relationships between PM2.5 concentrations and hospital admission on healthy days, unhealthy days for sensitive people, and unhealthy days.