Characterizing relations of extreme heat with cardiovascular and pulmonary outcomes and identifying intervention points for health system action to protect health in the context of climate change

Frequent, intense, and long-lasting heat events pose a significant and growing risk to human health. Heat-related morbidity and mortality result not only from heat illnesses but also from exacerbation of chronic diseases, including adverse cardiovascular and pulmonary outcomes. In this way, extreme heat adds to an already substantial public health burden in the United States from these conditions. Health systems have a critical role to play in protecting patients and the communities they serve from health impacts of extreme heat. To inform health system efforts to reduce risks to patients and their communities, the proposed research will systematically identify characteristics of heat exposure that prompt or exacerbate cardiovascular and pulmonary conditions and evaluate how individual and community features strengthen or reduce relations between extreme heat and health. We will study acute events for chronic health conditions, selected based on their public health burden and probability of exacerbation by heat: exacerbations of asthma and chronic obstructive pulmonary disease; coronary artery disease events, including angina pectoris and acute myocardial infarction; congestive heart failure; and stroke. The study will be conducted at Geisinger, a large integrated health system serving a socioeconomically and geographically heterogeneous population in central and northeast Pennsylvania. We will use Geisinger electronic health record data to identify emergency department visits and hospitalizations for the study outcomes, linking patients via their residential address to data on heat exposure. Through a set of outcome-specific case-crossover analyses, we will first rigorously assess several parameters of extreme heat (intensity, latency, duration) and modification by acclimatization in association with acute onset of the health outcomes, accounting for air pollution, to establish heat levels at which intervention is warranted. To identify heat-sensitive individuals and communities to inform potential points of intervention, we will investigate moderators of heat-health associations, including individual factors (e.g., age, various health factors, use of medications that alter physiology and thermoregulation) and community features that increase heat vulnerability (e.g., population susceptibility to heat, built and natural environment features such as greenness, access to services such as cooling facilities). We will develop heat vulnerability indices that may prove useful in identifying heat-sensitive communities and individuals for future intervention. To accelerate translation of our epidemiologic findings into action, we will also engage health system stakeholders to solicit input on intervention development. Developing acceptable, feasible, and effective interventions requires understanding stakeholders’ perspectives regarding interventional needs, priorities for future action, and obstacles and facilitators of such action. The knowledge gained through this project is essential to meeting our long-term goal to develop, implement, and evaluate multilevel health system interventions to protect patients from the health consequences of extreme heat.