A recent multicenter clinical trial investigating the impact of HEPA-14 air purifiers on respiratory infections in residential aged-care facilities (RACFs) has yielded mixed results, highlighting the complexities of infection prevention in elderly care settings.
The double-blind, crossover randomized study, conducted between April and October 2023 across three Australian RACFs, examined the effectiveness of in-room air purification systems in reducing acute respiratory infections (ARIs), including respiratory syncytial virus (RSV), influenza, COVID-19, and rhinovirus.
Disease Burden and Study Context
RSV poses a significant threat to older adults, resulting in approximately 160,000 hospitalizations and 10,000 deaths annually in the United States. While symptoms typically manifest as mild cold-like illness in healthy adults, they can become severe in elderly populations, particularly those in residential care settings.
Study Design and Implementation
The trial enrolled 135 participants, with 70 individuals assigned to the intervention-first group and 65 to the control-first group. The study population had a mean age of 85.2 years, with 78 female participants. Researchers installed air purifiers with HEPA-14 filters in intervention group rooms, while control group rooms received units without HEPA filtration.
The air purification systems were programmed to deliver a minimum of 8 air changes per hour during daytime operation and 3 air changes per hour at night. After three months, the groups switched interventions as part of the crossover design.
Key Findings and Clinical Implications
The intention-to-treat analysis revealed that HEPA-14 filtered air purifiers did not significantly reduce ARI incidence compared to control units. However, a subsequent analysis of the 104 participants who completed the full study protocol showed more promising results:
- Control group: 35.6% ARI incidence
- Intervention group: 24% ARI incidence
"Although the study results were not statistically significant, they may be clinically important," noted the study authors. "A reduction in the absolute number of ARIs among participants using the intervention who completed the study was identified."
Technical Considerations
The researchers emphasized the complexity of ARI prevention, stating that "successful prevention of ARIs requires a thorough understanding of pathogen transmission." They identified multiple factors affecting transmission risk, including:
- Pathogen-containing aerosol emission rates
- Removal rates
- Exposure levels
- Cumulative dose
- Probability of infection
The study also tracked secondary outcomes, including emergency department visits, hospital admissions, and medical reviews related to ARIs, though these results were not specifically highlighted in the findings.
