Asthma Precautions Largely Ineffective for Students with Active Asthma

Wanda Phipatanakul, MD, MS

Recent data from Boston suggested that use of a school-wide integrated pest management (IPM) or classroom high-efficiency particulate air (HEPA) filter purifiers did not significantly reduce symptom-days with asthma among children with active asthma.

Investigators led by Wanda Phipatanakul, MD, MS, Boston Children’s Hospital, reported that urban minority populations had experienced greater asthma-related morbidity and mortality than nonurban, nonminority counterparts.

Additionally, environments such as elementary schools were cited as sources of “occupational environmental asthma triggers” for children.

Previous studies such as the School Inner- City Asthma Study, detected mouse allergens in 99% of school dust samples that were associated with asthma morbidity, independent of home exposure and sensitization. A separate, clinical trial reported that classroom HEPA filter purifiers reduced allergen particles as measured by fine particulate matter (PM2.5) by approximately 45% compared with sham HEPA filter purifiers.

The study lacked data on overall health effects, however.

As such, Phipatanakul and colleagues conducted The School Inner-City Asthma Intervention Study, which test the efficacy of a school-wide IPM program and use of HEPA filter purifiers in the classrooms for reducing asthma morbidity.

The Study

The clinical trial was conducted at 41 urban elementary schools in the Northeastern US.

Recruitment began on April 1, 2015, with a total of 247 children with asthma enrolled in the study, with 236 being randomized into equal-sized treatment groups.

Prior to randomization, participants were involved in a screening visit that included questionnaires, allergy skin testing to 14 common aeroallergens (ALK-Abelló) using the MultiTest II device (Lincoln Diagnostics), standard procedures,and spirometry (Koko, Respitech) per guidelines from the American Thoracic Society.

Baseline environmental assessments were conducted via 1-week air samples, which were immediately followed by vacuum-settled dust samples from each student’s primary classroom.

Active or sham HEPA air purifiers were installed in each primary classroom and were replaced every 3 months for maximum efficiency. This was considered 1 of 2 interventions, the second being a the IPM intervention that focused on surrounding areas that fed into the student’s primary classroom and could harbor infestation by food and water sources

Asthma-related health outcomes were recorded through a parent survey. The primary outcome was the number of symptom-days with asthma during a 2-week period, and secondary outcomes were school absences, data from the Composite Asthma Severity Index, health care use, pulmonary function testing, and forced expiratory flow between the 25% and 75% of FVC.

The Findings

Phipatanakul and colleagues recorded no statistically significant interaction between the 2 interventions (incidence rate ratio [IRR], 0.43 [95% CI, 0.12- 1.49], P = .18 for interaction).

No statistically significant differences were found for most of the secondary outcomes as well.

Investigators noted that the 2-week mean was 0.11 missed school days due to asthma after use of the school-wide IPM program vs 0.17 days after no IPM across the school year.

Additionally, the school-wide IPM program did not significantly reduce any of the measured allergens or particles. However, the use of the HEPA filter purifiers significantly reduced airborne mouse and dog allergen particles compared with the sham HEPA filter, adjusting for differences prior to the intervention and for the use of the school-wide IPM program.

Overall, the trial showed that neither the program or filter purifiers significantly reduce the number of symptom-days in children with asthma during a 2-week period.

Despite this, the team believed certain considerations were necessary when reviewing the data, and that future studies might present alternative findings.

“However, interpretation of the study findings may need to consider allergen levels, particle exposures, and asthma symptoms at baseline,” the investigators wrote.

The study, “Effect of School Integrated Pest Management or Classroom Air Filter Purifiers on Asthma Symptoms in Students with Active Asthma A Randomized Clinical Trial,” was published online in JAMA Network.