Effect of School Integrated Pest Management or Classroom Air Filter Purifiers on Asthma Symptoms in Students With Active Asthma: A Randomized Clinical Study

Abstract

To determine if environmental control measures (1) school-wide integrated pest management (IPM) program and/or (2) use of high-efficiency particulate air (HEPA) filter purifiers in inner city elementary school classrooms would reduce asthma morbidity in students with active asthma.Forty-one inner city elementary schools in the Northeastern United States were recruited for this study. There were 236 students with active, physician-diagnosed asthma randomized to IPM (by school) and/or HEPA filter purifiers (by classroom). Physician-diagnosed asthma was defined as the child having had unscheduled doctor visits, hospitalization, corticosteroid bursts, symptoms, or controller medication use in the past year. Fifty seven percent of the children were Hispanic and 24% were Black. Mean age was 8.1 years, 48% female, mean FEV1 97% to 99.7% predicted at randomization. Forty-fifty percent of the children were using short acting β agonists alone and the rest were on inhaled corticosteroids and/or leukotriene modifiers. The study was conducted during the school years 2015 to 2020.All students with active physician-diagnosed asthma had a screening visit with questionnaires, skin testing, and spirometry as well as 2 follow-up visits with the same assessments during the year. Baseline environmental assessment for a panel of allergens (mouse, rat, dust mite, cockroach, cat, dog, Alternaria alternate, and Aspergillus fumigatus) were conducted at the schools by collecting a 1-week air sample, immediately followed by vacuum–settled dust samples from each students’ primary classroom and in the participants homes. The allergens were analyzed using a multiplex assay (MARIA, Indoor Biotechnologies). Follow-up environmental assessment after randomization took place once each winter and spring during the school year.The allocation to free standing classroom HEPA filter purifiers, active or sham, was blinded to the participants and those assessing the outcomes. The IPM program consisted of application of rodenticide, sealing entry points, trap placement, targeted cleaning, and brief educational handouts for the school staff. Infestation was assessed every 3 months and IPM reapplied as needed. Trained pest management specialists providing the school-wide IPM program were unblinded, but the student participants and trial investigators remained blinded throughout the trial.Four groups of 59 students each were randomized using a factorial design to either intervention alone, both interventions together, or neither for the entire school year. Classroom and home allergen and particle levels at randomization were balanced between the 4 groups.The asthma-related health outcomes of the students were assessed by parent survey at baseline and every 2 months until the end of the school year. The primary outcome was the number of symptom-days with asthma during a 2-week period assessed over the 10 months of randomization. Prespecified secondary outcomes were school absences, Composite Asthma Severity Index score, healthcare utilization, and spirometry measurements.Ninety eight percent of the classrooms had detectable levels of mouse allergen and 26% of the participants were sensitized to mouse allergen. More than 90% of baseline classroom allergen levels for cockroach, rat, Alternaria, Aspergillus and dust mite were undetectable.Use of the school-wide IPM program resulted in a mean of 1.5 symptom-days with asthma during a 2-week period versus 1.9 symptom-days for no IPM; use of HEPA filter purifiers resulted in a mean of 1.6 symptom-days with asthma versus 1.8 symptom-days for sham HEPA filter purifiers; neither comparison was statistically significant. Other prespecified secondary outcomes, including healthcare utilization or missed school days because of asthma also did not differ significantly between the intervention groups. The HEPA filter purifiers significantly reduced mouse and dog allergens in the classrooms. The IPM program did not significantly reduce concentrations of any of the allergens or particles measured. A post hoc exploratory analysis found a statistically significant association of reduction in asthma symptoms with the school wide IPM program but only for a limited time (mid-November to February).In an inner-city population of elementary school students with active asthma, use of a school-wide IPM program or HEPA filter purifiers in the classrooms did not significantly reduce symptom-days with asthma.It is possible that these children had asthma that was too mild to see a significant difference in these environmental interventions. Also unclear is whether resources to perform environmental control measures are best used at the school level or at home. As an accompanying editorial notes, “as allergen sensitization is related to the pathogenesis and pathophysiology of childhood asthma,” allergen avoidance should still be a basic tenet of treatment and worth continued investigation.URL: www.pediatrics.org/cgi/doi/10.1542/peds.10.1001/jama.2021.11559