Lessons from the HEPA Filter RCT in JAMA-IM
It’s only been a few years from the pandemic. Remember HEPA filters?
A CDC study (observational) reported HEPA filters reduce COVID-19 spread in schools. The doctors of British Columbia wrote in favor of HEPA filters.
Here is a good one from the Journal of Infection and Public Health:
Science tells us that portable air filters reduce infection risk. It’s time for public health authorities to make this clear.
There are even studies that show HEPA filters remove virus from the air.
This week, JAMA-IM published the pragmatic AFRI-c cluster randomized trial where portable high-efficiency particulate air filters were tested in nursing homes in the UK.
This was a 2-arm cluster RCT conducted in nursing homes in the UK. The active arm included up to 5 HEPA filters for communal areas and up to 16 filters for bedrooms. The control arm continued normal procedures.
The primary outcome was respiratory infection per winter per bedroom resident (exposed to bedroom and communal room filters). Secondary outcomes included staff absenteeism.
Approximately 243 homes were invited to participate and 95 were ultimately randomized. Care home residents were included if expected to reside in a single-occupancy bedroom (the UK norm) for at least 1 month and excluded if expected to die within 7 days or were participating in a conflicting study.
The number of HEPA filters, and filter settings, were selected to balance clean air delivery rate (CADR) with acceptability to residents (noise and air flow cooling).Staff were provided with manufacturer guidance about how to maximize HEPA filter efficiency and with labels to remind staff and all residents to keep all units switched on.
Results:
Randomization was at the level of the care home and the study was conducted over three winters. Baseline characteristics of the homes and bedroom residents were balanced. These were mostly female individuals, median age 88 years.
There was no evidence of a difference in the number of respiratory infections per winter per intervention vs control bedroom residents (0.99 vs 1.04; adjusted incident rate ratio, 0.92; 95% CI, 0.64-1.33; P = .67).
There was also no evidence of a difference in the rates of staff absenteeism (adjusted incident rate ratio, 0.80 95% CI, 0.55-1.16; P = .24).
The authors offer a cost-saving analysis:
Assuming each care home uses 15 filters, the costs of implementing air filters over the first 5 years would be approximately £10 275 (US $13 830) per care home. With approximately 15 000 care homes in England, the budget impact could be as much as £154 million (US $207 million) if HEPA filters were implemented in every care home.
