Randomized Clinical Trial of Air Cleaners to Improve Indoor Air Quality and COPD Health: Results of the CLEAN AIR STUDY

Background: Indoor particulate matter is associated with worse outcomes in adults with COPD. It remains unknown whether reductions of indoor pollutants can improve respiratory morbidity. Methods: Eligible former smokers with moderate-severe COPD received active or sham portable HEPA air cleaners and were followed for 6 months in this blinded randomized controlled trial. The primary outcome was 6-month change in Saint George’s Respiratory Questionnaire (SGRQ) . Secondary outcomes were exacerbation risk, respiratory symptoms, rescue medication use and 6MWD. Intention to treat analysis included all subjects and per protocol analysis included adherent participants (greater than 80% use of air cleaner). Findings: 116 participants were randomized of which 84.5% completed study. There was no statistically significant difference in improvement of total SGRQ, but the active filter group had greater reduction in SGRQ symptom subscale (s -7.7 [95% CI, -15.0 to -0.37]) and respiratory symptoms (BCSS, s -0.8 [95% CI, -1.5 to -0.1); and lower risk of moderate exacerbations (IRR 0.32 [95% CI, 0.12-0.91]) and rescue medication use (IRR 0.54 [95% CI, 0.33-0.86]) compared to sham group (all p<0.05). In per protocol analysis, there was statistically significant difference in primary outcome’s improvement (SGRQ) between the active filter vs. sham group (β-4.76 [95% CI, -9.2 to -0.34]) and in moderate exacerbation risk, BCSS and 6MWD. Participants spending more time indoors were more likely to have treatment benefit. Interpretation . This is the first environmental intervention study conducted among former smokers with COPD showing potential health benefits of portable HEPA air cleaners, particularly among those with greater adherence and spending a greater time in their home. Trial Registration: clinicaltrials.gov Identifier: #NCT02236858 Funding: The Clinical trial of air cleaners to improve indoor air quality and COPD health (CLEAN AIR) was supported by NIEHS R01ES022607 and T32HL007534. Air cleaners used in this trial were donated by Austin Air Cleaners, however the company did not have any input on study design, analysis or manuscript preparation. Declaration of Interest: NNH reports grants from NIH, grants from COPD Foundation, grants and personal fees from AstraZeneca, grants and personal fees from GSK, grants from Boehringer Ingelheim, personal fees from Mylan during the conduct of the study. NP reports a grant from NIH K award, during the conduct of the study. RP reports grants from NIH during the conduct of the study and personal fees from the Health Effects Institute outside the submitted work. GD reports grants from NIH, during the conduct of the study. RW reports grants from Sanofi-Aventis, grants and personal fees from Verona and Boehringer Ingelheim, non-financial support from Propeller Health, personal fees from AstraZeneca, Contrafect, Roche-Genentech, Merck, Mylan/Thervance, AbbVie, GSK, ChemRx, Kiniksa, Bristol Myers Squibb, Galderma, Kamada, Pulmonx, Kinevant, Puretech, Arrowhead, VaxArt, Polarean, and Galderma, outside the submitted work. MD reports grants from National Institutes of Health, Office of the Director, during the conduct of the study. AR reports grants from NIH, during the conduct of the study. MCM reports grants from NIH and EPA during the conduct of the study, personal fees from Aridis, GSK and Celgene outside the submitted work. KK reports grants from NIH, during the conduct of the study. HW, AF, KR, ME, PB have nothing to disclose. Ethical Approval: Participants provided written informed consent and the Johns Hopkins Medical Institutional Review Board approved the protocol (NA_00085617).