The National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Environmental Health Sciences (NIEHS), both part of that National Institutes of Health (NIH), joined the Environmental Protection Agency (EPA) in convening multidisciplinary experts in areas of cardiopulmonary health effects of particulate matter (PM); large cardiovascular clinical trials; exposure assessment; and air quality interventions to improve health.
The health effects of PM air pollution have been extensively studied in the last two decades, with increasing understanding of acute and chronic exposures, biologic mechanisms, and pulmonary and non-pulmonary disease outcomes. Among the non-pulmonary health effects most studied are effects on cardiovascular disease. The recent wildland fires, both planned and unplanned, have greatly increased the need for public health guidance and clinical recommendations on strategies to reduce individuals’ exposure to PM. Additionally, the Million Hearts 2022 initiative undertaken by the Centers for Disease Control and Prevention (CDC), and the Centers for Medicare and Medicaid Services, has targeted avoiding exposure to PM as one of its goals for individuals with clinical cardiovascular disease (myocardial infarction and stroke), which will likely increase clinical interest in interventions to reduce exposures.
Individual-based intervention strategies, such as using more effective air filters in the home and wearing respirators when going outside, have not been adequately tested in cardiovascular research studies to determine their efficacy and real-world effectiveness. There is a need for further scientific testing of these intervention strategies, particularly in vulnerable populations who are at higher risk. Scientific studies are needed to determine whether interventions that reduce PM exposure also affect relevant biomarkers and health outcomes. Such studies may also provide an opportunity to examine possible synergistic effects of PM with other non-pollution related risk factors for pulmonary and cardiovascular disease. We currently do not know how feasible such studies in large populations are, what initial studies would be informative, and which United States vulnerable populations are the highest priority for study.
Discuss feasible trials or other research designs that will address the efficacy and effectiveness of existing personal interventions in reducing mechanistic, cardiovascular, and respiratory health outcomes in vulnerable populations.
Discussions were centered around several areas. The participants considered what is known about acute and chronic PM associations with major cardiovascular and pulmonary diseases including the strength of the evidence for the chronic effects of PM on coronary artery disease, heart failure, cardiovascular death, and chronic pulmonary disease. There was a presentation about the biological mechanisms underlying the health effects of PM and a synopsis of the current level of PM exposures in the United States. Participants also engaged in a dialogue on what populations are most vulnerable to the adverse effects of PM, including populations with cardiopulmonary disease. There was a particular focus on individuals with chronic clinical cardiovascular diseases. Several high-risk populations were identified that might be included in clinical trials of personal interventions.
This discussion was followed by consideration of personal intervention methods to reduce PM exposure, including interventions directed at reducing exposures in residential dwellings and in individual rooms within a dwelling. The length of time that these personal interventions have been used in past studies was reviewed. The advantages and disadvantages of the competing interventions were discussed from a variety of perspectives including their efficacyand acceptability to individuals in research studies.
The discussion of interventions was followed by consideration of what cardiovascular health outcomes should be a high priority for studies of efficacy and effectiveness. There was also a dialogue about the inclusion of pulmonary outcomes in cardiovascular health outcome trials. The identification of research subjects who are likely to be at high risk for clinical cardiovascular or pulmonary events during a study was reviewed. There was a dialogue on the types of exposures to air pollutants that might be measured during large studies and the frequency of their measurement. Discussants reviewed the lessons from more traditional and newer pragmatic cardiovascular trials as they relate to the recruitment of trial participants, identification of trial outcomes, and size of trial populations. Finally, there was a dialogue about research gaps that should be further reviewed and addressed before large trials are undertaken.
At the conclusion of the workshop, there was general agreement that, when planning a large-outcomes trial in the United States, several questions should be addressed to improve the likelihood of meaningful results that would successfully answer its important scientific hypotheses. An For example, it is important to consider the size of the eligible population for the trial, which would depend on the geographic areas to be included in the trial and on other inclusion factors, such as the disease characteristics of the participants. Another important question is the degree to which participants can be expected adhere to the proposed intervention strategies to reduce PM exposures . A related important question is whether a trial should include more than one intervention strategy.
The meeting participants will develop a workshop report, highlighting the main objectives of the meeting and key recommendations. The report will be published in a peer reviewed journal.
Lawrence J. Fine, MD, DrPH
Division of Cardiovascular Sciences, NHLBI
Presenters and Discussants
NIH and EPA Staff Attendees