Browsing by Subject "Case-crossover"
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Item Extreme weather and mortality among a nationwide cohort of Veterans with COPD(2023) Rau, AustinClimate change is increasing the frequency, severity and duration of extreme weather events. Individuals with climate sensitive diseases such as chronic respiratory diseases are at an enhanced risk of health challenges due to climate change. However, there is a lack of individual level studies examining how extreme weather events such as heat and cold waves may increase the risk of mortality among individuals with chronic obstructive pulmonary disease (COPD), a climate sensitive respiratory disease. Using nationwide individual level health data from the Veterans Health Administration, three studies were designed to estimate heat and cold wave associated mortality risk among this susceptible population.The first study evaluated heat and cold wave mortality risk among the entire population of patients with COPD and examined health disparities by individual characteristics including gender, age, race and ethnicity. Results indicated cisgender females had an increased heatwave associated mortality risk. While some racial disparities in mortality risk were detected, the evidence was weak. The second study further examined disparities in heat and cold wave associated mortality via less commonly studied effect measure modifiers including comorbidities, smoking status and urbanicity. Patients with concurrent COPD and asthma had a greater risk of heatwave related mortality whereas patients with COPD alone had the greatest cold wave associated mortality risk. Smokers and patients living in urban settings had enhanced risk of both heat and cold wave related mortality. The third study assessed the added mortality risk incurred during compound climate hazards (droughts and heatwaves) among this susceptible population. Results indicated heatwaves that occurred during droughts had larger mortality risks compared to heatwaves during non-drought conditions. These three studies provide evidence that individuals with COPD are at risk of adverse health events from heat and cold waves and identified heterogeneities in risk based on characteristics including social, biological and geographical constructs. There is an apparent need in climate and health epidemiology for more large-scale individual level assessments of people with climate sensitive diseases. As contemporary impacts of climate change are realized, it is imperative to devote resources and energy into elucidating health risks associated with extreme weather events to identify and protect at-risk segments of the population.Item Investigating Infection-Related Hospitalization as a Risk Factor for Incident Heart Failure and Mortality among Heart Failure Patients(2023-06) Molinsky, RebeccaHF is a growing epidemic with an estimated prevalence of 6.5 million individuals in the U.S., and poor outcomes persist despite recent therapeutic advancements. Studies have shown that an inflammatory response to infections may become dysregulated, thereby promoting collateral myocardial damage that may result in HF. Infection is also a common cause of hospitalization among HF patients and may lead to poor prognosis and high mortality. Limited data exist examining the relationship between infection-related hospitalization (IRH) and HF along with HF subtypes, HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). Further, few studies have explored mortality rates following an IRH in HF patients or whether certain types of IRH are stronger predictors of mortality. This dissertation leveraged the strengths of large claims data (MarketScan) and a community-based study (ARIC) to address these limitations and parse out the dynamic relationship between infection-related hospitalization and HF with several manuscripts. The first manuscript, a case-crossover study of beneficiaries in the MarketScan databases, assessed the association between IRH and incident HF. IRH was associated with incident HF after both 1- and 3-months. The second manuscript investigated the association between IRH and long-term incident HF in the Atherosclerosis Risk in Communities study (ARIC). IRH was associated with a two-fold greater risk of incident HF, HFrEF, and HFpEF. Findings were stronger among those with HFpEF, for which treatment options are limited. Results from the first manuscript aligned with those of the second manuscript and both found respiratory, pneumonia, and blood/circulatory infections to have the strongest associations with incident HF. The third manuscript explored the relationship between IRH and mortality among HF patients in ARIC. IRH was associated with a two-fold greater risk of mortality among those with HFpEF, HFrEF, or unclassified HF. Respiratory, pneumonia, and other infections had the strongest associations with mortality. Our findings support prior literature linking IRH to HF risk and increased mortality among HF patients. These findings may have significant population-level implications given the high prevalence of IRH and the burden of HF on our aging society. Aim 1: Investigate the association between infection-related hospitalization and incident HF using U.S.-based claims data from MarketScan. Aim 2: Investigate the association between infection-related hospitalization and incident HF and HF subtypes (HFrEF or HFpEF) using a longitudinal community-based cohort study, ARIC. Aim 3: Among HF (HFrEF and HFpEF) patients, investigate the association between infection-related hospitalization and mortality using a longitudinal community-based cohort study, ARIC.