Study protocol for a 1-year, randomized, single-blind, parallel group trial of stand-alone indoor air filtration in the homes of US military Veterans with moderate to severe COPD in metropolitan Chicago.

Background: Exposure to air pollutants in indoor and outdoor air is associated with adverse chronic obstructive pulmonary disease (COPD) outcomes. To date, few studies have investigated indoor air filtration for improving indoor air quality and health-related outcomes in vulnerable patient populations with COPD.

Methods: This study seeks to evaluate the effectiveness of stand-alone air filtration for reducing residential indoor particulate matter concentrations and improving health-related outcomes in a high-risk urban cohort of US military Veterans with COPD in metropolitan Chicago using a long-term (1-year), randomized, single-blind, placebo-controlled, parallel group trial. Participants are randomized to receive a placebo/sham unit or a normally functioning filtration unit containing high efficiency particulate air (HEPA), activated carbon, and zeolite media. Low-cost sensors are used to measure particulate matter concentrations and plug load data loggers are used to measure air cleaner operation at high time resolution in each home throughout the study duration. The primary outcome is physician-diagnosed exacerbations of acute COPD. Secondary outcomes include changes in health-related quality of life (HR-QoL), assessed at recruitment and after 12 months of intervention using the COPD-specific version of the St. George's Respiratory Questionnaire (SGRQ-C) and Veterans RAND 36-Item Health Survey (VR-36), and clinical outcomes (e.g., emergency room and unscheduled medical visits, 6-min walk distance (6MWD), oxygen saturation) assessed at baseline, endline, and throughout the study. Housing condition assessments are also conducted to characterize participant homes and housing-related factors that may contribute to COPD exacerbations or influence the effectiveness of the intervention. Our goal is to recruit 80 participants. The study population is expected to be predominantly African American, with a significant proportion living in historically underserved, lower socioeconomic status neighborhoods.

Discussion: Outcomes from this pragmatic, real-world trial have the potential to inform policy and practice in both healthy housing and patient medical care by evaluating the impacts of long-term use of stand-alone portable air filtration on indoor pollutant concentrations and COPD outcomes in a high-risk cohort. This trial also offers the potential for providing novel data on associations between housing conditions and COPD outcomes and providing novel insight into air cleaner operation in this vulnerable population.

Trial Registration: ClinicalTrials.gov: NCT05913765. Registered on June 22, 2023.