Short-term PM2.5 exposure and early-readmission risk: A retrospective cohort study in North Carolina Heart Failure Patients
Background
Short-term changes in ambient fine particulate matter (diameter ≤ 2.5 μm, PM2.5) air pollution increase the risk for cardiovascular hospital admission and readmission.
Objectives
Associations described in prior studies were reported using low-resolution PM2.5 data from city monitors and large administrative regions. Here we improve on these methods and utilize fine-resolution air pollution data to examine the PM2.5-related 30-day readmission risk in heart failure (HF) patients and examine how this risk varies with respect to time following discharge.
Methods
We performed a retrospective cohort study of 17,674 patients with a recorded HF diagnosis between 2004 and 2016. The cohort was identified using the EPA CARES electronic health record resource. The association between daily PM2.5 and 30-day readmissions were evaluated using time-dependent Cox proportional hazard models. Fine-resolution ambient PM2.5 data were assigned to patient residential address and hazard ratios are expressed per 1 μg/m3 of PM2.5.
Results
The hazard of a PM2.5-related readmission within three days of discharge was 1.029 (95% CI 1.017-1.042). This PM2.5 readmission hazard was significantly elevated in non-urban areas (1.036, 95%CI 1.020-1.052) and for events not preceded by a prescription for a beta-blocker (1.030; 95% CI 1.018-1.043).
Conclusions
Our findings add to the evidence indicating increased air quality-related health risks in individuals with underlying cardiovascular disease. Hospital readmissions are key metrics for patients and providers alike. As a potentially modifiable risk factor, air pollution-related interventions may be enacted that might assist in reducing costly and burdensome unplanned readmissions.