HEPA air purifiers cannot cope with respiratory infections in elderly care facilities

A clinical study found no significant differences in the incidence of respiratory infections among senior care facility residents using HEPA-14 air purifiers.

Test: Air purifiers and acute respiratory infections in nursing homes for the elderly. Photo credit: Dmitry Galaganov/Shutterstock.com

Patients living in aged care facilities (RACF) may be at greater risk of respiratory infections. A recent study published in JAMA network open is investigating whether high-efficiency portable indoor air purifiers can support reduce this risk.

ARI and air purification

Acute respiratory infections (ARIs) pose a persistent and significant risk to the health of older adults, especially those living in long-term care facilities. Reducing this risk requires breaking the chain of transmission, as aerosols are a common way for respiratory pathogens to spread.

Effective prevention efforts should focus on reducing aerosol emissions, increasing aerosol removal rates, reducing exposure to respiratory pathogens, and ultimately reducing the risk of infection. Ensuring pristine air is therefore a key element of prevention in this environment.

Portable air purifiers have grown in popularity, but there is constrained evidence to support their effectiveness. This gap formed the basis of the current study, which tested the effect of high-efficiency indoor air purifiers on reducing the risk of ARI among residents of aged care facilities (RACFs).

About the study

The study took the form of a randomized clinical trial (RCT) in which participants switched from one arm to the other after a set period of time. This would give all participants the opportunity to experience the intervention at some point.

The number of participants was 135, of which 58% were women. The average age was ~85 years.

Half of the participating residents’ rooms were equipped with high-efficiency particulate matter (HEPA)-14 filters (n + 70), while air purifiers in the remaining rooms were not equipped with these filters (n = 65). Participants completed the study after three months.

The incidence of ARI was measured by the sudden onset of symptoms such as sore throat, icy symptoms, shortness of breath or cough that the doctor considered to be caused by a respiratory infection.

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

In addition to the incidence of ARI, the duration of disease until the first infection, the number of visits to emergency departments and hospitalizations, and medical visits due to ARI were assessed.

The impact of air purifiers on acute risk

The results of this experiment, based on the incidence of ARI in the intention-to-treat (ITT) groups in both arms of the study, showed no significant reduction in the risk of ARI among participants using HEPA filters. However, separate analysis of both phases of the study revealed a difference in the first phase: 30% of the intervention group experienced ARIs compared with 44.6% of the control group, suggesting a potential benefit from the exploit of a HEPA filter.

After a three-month crossover, there was no significant difference in risk between the groups, which was likely influenced by the first phase ending during the ARI winter peak in Australia, as shown by historical epidemiological data.

Only 104 participants completed the entire study, with the majority (87.5%) of those who did not complete the study dying during the study period. Further analysis of the subgroup that completed the study showed that the risk of ARI was 25% in the HEPA group compared to 35.6% in the no-HEPA filter group, resulting in a 47% reduction in ARI risk for HEPA users.

No changes were observed in the intervention group at the time of first infection. Of note, 75.3% of participants who experienced ARI required a physician visit, and 10 participants (13.7%) required transfer to the emergency department for urgent care.

Application

Indoor portable air purifiers equipped with HEPA-14 filters did not reduce the risk of ARI among participants, although a difference was observed after phase analysis. This means that in phase 1, the incidence of ARI decreased in HEPA recipients, but not in phase 2.

Notably, the proportion of ARI patients requiring medical attention dropped significantly to 75%, as did the proportion of patients requiring treatment in the Emergency Department. This suggests that the intervention may be clinically significant even if statistical significance was lacking.

Further research will be necessary to confirm and extend these findings to a more diverse and larger population, improving the quality of health care in this system.