HEPA air purifiers fall short in cutting respiratory infections in aged-care facilities

By Dr. Liji Thomas, MDReviewed by Lily Ramsey, LLMNov 13 2024

Clinical trial reveals no significant difference in respiratory infection rates among aged-care residents using HEPA-14 air purifiers.

Study: Air Purifiers and Acute Respiratory Infections in Residential Aged Care. Image Credit: Dmitry Galaganov/Shutterstock.com

Patients in residential aged-care facilities (RACFs) may face a higher risk of respiratory infections. A recent study published in JAMA Network Open explores whether high-efficiency in-room portable air purifiers could help reduce this risk.

ARIs and air purification

Acute respiratory infections (ARIs) pose a persistent and significant health risk to elderly individuals, particularly those in long-term care facilities. Reducing this risk requires breaking the chain of transmission, as aerosols are a common mode of spreading respiratory pathogens.

Effective preventive efforts should focus on reducing aerosol emissions, increasing aerosol removal rates, lowering exposure to respiratory pathogens, and ultimately decreasing infection risks. Establishing clean air is, therefore, a critical component of prevention in this setting.

Portable air purifiers have grown in popularity, but there is limited evidence supporting their effectiveness. This gap prompted the current study, which tests the impact of high-efficiency room air purifiers on reducing the risk of ARIs among residents in residential aged-care facilities (RACFs).

About the study

The study took the form of a randomized clinical trial (RCT) where participants crossed over from one arm to the other after a specified interval. This would give all participants the opportunity to experience the intervention at some point.

The number of participants was 135, with 58% being female. The mean age was ~85 years.

Half of the participant residents’ rooms were fitted with high-efficiency particulate air (HEPA)-14 filters (n + 70), while the air purifiers in the rest of the rooms did not have these filters (n = 65). Participants crossed over after three months.

The incidence of ARIs was measured based on the sudden onset of symptoms like sore throat, cold symptoms, shortness of breath, or cough that were thought by a medical professional to be due to a respiratory infection.

The specific pathogens were recorded if diagnostic testing was done, such as influenza A and B viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus (RSV), or rhinovirus.

Along with the ARI incidence, patients were assessed for duration till the first infection, the number of emergency department visits and hospital admissions, and doctor visits because of an ARI.

The effect of air purifiers on acute risk

The results of this experiment, based on ARI incidence in the intention-to-treat (ITT) groups in both study arms, did not show a significant reduction in ARI risk among participants using HEPA filters. However, a separate analysis of the two study phases revealed a difference in the first phase: 30% of the intervention group developed ARIs compared to 44.6% of the control group, suggesting a potential benefit from HEPA filter use.

After the three-month crossover, there was no significant difference in risk between the groups, likely influenced by the first phase concluding at the winter peak of ARIs in Australia, as shown by historical epidemiological data.

Only 104 participants completed the entire study, with the majority (87.5%) of non-completers due to death during the study period. Further analysis of the subgroup that completed the study found a 25% ARI risk in the HEPA group versus 35.6% in those without HEPA filters, resulting in a 47% reduction in ARI risk for HEPA users.

No change was observed at the time of the first infection in the intervention group. Notably, 75.3% of participants who developed an ARI required a doctor’s visit, with 10 participants (13.7%) needing emergency department transfer for urgent care.

Conclusion

In-room portable air purifiers with HEPA-14 filters did not reduce the ARI risk among participants, though a difference was observed when phase-based analysis was performed. That is, in phase 1, the incidence of ARIs dropped in HEPA recipients but not in phase 2.  

Notably, the proportion of ARI patients who required medical help fell considerably to 75%, as did the fraction who had to be treated in the ED. This suggests that the intervention might be clinically significant even though statistical significance was missing.

Further studies will be essential to validate and extend these findings to a more diverse and larger population, improving healthcare quality within this system.