A Randomized Controlled Trial of Home Air Purification for Eosinophilic COPD

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PROJECT SUMMARY/ABSTRACT Chronic obstructive pulmonary disease (COPD) is an incurable and deadly disease that affects 15% of adults over 40 years of age in the United States, and is exacerbated by exposure to air pollution. Up to 40% of COPD patients have a more inflammatory subtype with eosinophilia (>150 eosinophils per µL) and appear to be more responsive to anti-inflammatory medications, including inhaled steroids and novel targeted antibodies that block eosinophil formation. However, these medications are expensive and have adverse side effects. It is unknown if prevention of exposure to air pollution and allergens—which have been demonstrated to interact with each other to cause airway inflammation—may be of therapeutic benefit in eosinophilic COPD. High efficiency particulate air (HEPA) purifiers hold great promise to improve COPD symptoms and lung function, because they effectively remove particles from the indoor air, including traffic-related particles that are associated with reduced lung function in COPD, and allergens that can provoke airway inflammation, especially in those with atopy which is common in eosinophilic COPD. Recent studies have found that HEPA filters improve symptoms and lung function for allergic asthma, but this intervention has never been evaluated for eosinophilic COPD. The overall objective is to evaluate the effect of a one-year blinded randomized controlled trial of a HEPA vs sham air purifier intervention on lung function, respiratory symptoms, and the upper respiratory tract (as a site of inhaled exposure and biologic response) among 200 former smokers with eosinophilic COPD. The central hypothesis is that removal of particles in the bedroom and living room by a HEPA air purifier will improve the respiratory health of patients with eosinophilic COPD. The first aim will test if a one-year HEPA filter intervention in the bedroom and living room affects lung function (primary outcome), respiratory symptoms, and health status compared to sham filter. The second aim will test if the intervention affects levels of inflammatory mediators in the nasal epithelial lining fluid. The third (exploratory) aim will evaluate if the intervention affects levels of certain dust- and combustion-related metals in the nasal epithelial lining fluid. The investigators hypothesize that improved air quality due to HEPA filters will improve lung function, respiratory symptoms, and health status by St. George Respiratory Questionnaire. It is further hypothesized that air purification will reduce inflammatory mediators relevant to allergic and non-allergic airway pathophysiology, and also reduce dust- and combustion-related metals in the upper respiratory tract. The findings of this project may provide the medical community with two new tools—(1) a HEPA filter intervention, and (2) an assay of upper respiratory exposure and response—that can be used to promote healthier lives among people with eosinophilic COPD. Without such knowledge, the medical community may miss an opportunity to reduce exposure to noxious particles that drive disease progression, and instead rely only on costly medications for disease control in this more inflammatory subtype of COPD.