Cardiovascular disease (CVD) is the leading cause of death in the US. There has been an increasing recognition of the important contribution of fine particulate pollution (PM 2.5 ) to CVD morbidity and mortality. Mounting evidence suggests that the use of indoor air filtration to reduce PM 2.5 exposure from days to weeks leads to improvement in acute atherothrombosis biomarkers. However, no trials have assessed whether these short-term effects are sustained or further improved with prolonged filtration.
The proposed study is the longest intervention trial investigating the effect of using low-cost air purifiers in residences on ameliorating atherothrombosis progressions in vulnerable individuals. The study will examine atherothrombosis responses to High Efficiency Particulate Air (HEPA) filtration across and within four subgroups of male or female and Hispanic or non-Hispanic participants. We will leverage the diverse population in Los Angeles to investigate the effect of indoor PM 2.5 filtration on both levels and slopes of change in atherothrombosis biomarkers including arterial stiffness, blood pressure, targeted proinflammatory and prothrombotic markers, and novel proteomic makers, as well as CVD risk score.
We have an experienced team of investigators at the University of Southern California (USC) and Duke University and will leverage the rich patient resource from the USC KECK electronic medical records and the linked census-track PM 2.5 data to enroll 100 participants of 65-84 years old non-smokers with a history of ischemic heart disease (clinically stable for at least 6 months) who have lived in the census track with higher ambient PM 2.5 exposure in the past years. Participants will be block-randomized to two intervention arms (HEPA or sham filtrations, each of 9-month duration) and crossed over to the other intervention arm after a 3-month washout period. Three home visits will be conducted during each intervention arm to set-up and calibrate air monitors, measure health outcomes, and collect biospecimens. Lifestyle and health covariates will be collected through online questionnaires. Indoor and outdoor PM 2.5 and co-pollutants will be measured; and meteorological data as well as wildfire events will be recorded throughout the trial. Findings of the proposed study will provide the efficacy and feasibility data to support future nationwide or multi-center trials to further investigate the air filtration effect on adverse CVD event incidence and mortality