School Pest Management Program Significantly Reduced Asthma Symptoms in Kids

Neither a school-wide integrated pest management (IPM) program nor the placement of classroom HEPA filter purifiers reduced the number of symptom-days in schoolchildren with asthma, according a recent study published in JAMA. Although researchers found large reductions in asthma symptoms early on, these reductions were not sustained in the long-run through the school year.

For the School Inner-City Asthma Interventional Study, Wanda Phipatanakul, MD, MS, of the Boston Children’s Hospital, and fellow researchers included 236 students (mean age: 8.1 years; 48% girls) with active asthma from 41 urban elementary schools throughout the Northeastern U.S.

“Schools are an important area to intervene. We aimed to see if we could make a difference in improving the health of urban children with asthma in a school environment since every child in America has to go to school and it as basically every child’s ’required occupation.’ Intervening in the schools could have tremendous impact because one could benefit a community of children in the school environment as opposed to single families or a single child at home,” she told BreakingMED.

Randomization to IPM was by school, and to HEPA filter purifiers by classroom. The IPM program was comprised of rodenticide application, entry point sealing, trap placement, targeted cleaning, and brief educational handouts for the school staff. Every 3 months, pest infestation was re-assessed and additional treatments applied when needed. Control schools had no IPM, cleaning, or education. Classrooms were given portable HEPA filter purifiers, with filters changed out every 3 months. Control classrooms were given sham HEPA filters.

The baseline 2-week mean symptom-free days were 2.2 in patients with asthma. In addition, almost all classrooms (98%) had detectable levels of mouse allergen.

Because researchers found no statistically significant difference between the interventions (P=0.18 for interaction), they pooled the results.

During a 2-week period, mean symptom free days were not significantly different in children with asthma who attended schools that implemented an IPM program and those attending schools with no IPM across the school year (was 1.5 versus 1.9 days, respectively; incidence rate ratio [IRR]: 0.71; 95% CI: 0.38-1.33).

During a 2-week period, researchers also found no significant difference in the number of symptom-days in children with asthma when comparing those in classrooms using HEPA filter purifiers and those with sham purifiers across the school year (1.6 versus 1.8 days, respectively; IRR: 1.47; 95% CI: 0.79-2.75).

Researchers found no significant differences for the majority of secondary outcomes, including Composite Asthma Severity Index, health care use, and pulmonary function. They did find a significant difference, however, in the reduction in the number of missed school days caused by asthma in children attending schools implementing the IPM program. In these kids, the 2-week mean was 0.11 missed school days, compared with 0.17 missed days in kids attending schools with no IPM (IRR: 0.20; 95% CI: 0.04-0.96).

In their post-hoc exploratory analysis, Phipatanakul and colleagues found a statistically significant improvement in the number of asthma symptom days for the IPM group during the first two postintervention visits, but not later visits.

Two weeks after the intervention, the 2-week mean was 1.1 symptom days in kids attending IPM program school compared with 2.5 symptom-days in those with no IPM (IRR: 0.37; 95% CI: 0.15-0.91). At 8 weeks after the intervention, however, the 2-week mean was 0.8 versus 1.5 symptoms-days respectively (IRR: 0.48; 95% CI: 0.23-0.99), and by 20 weeks after the intervention, these 2-week means were 1.3 versus 1.4 symptom-days, respectively (IRR: 0.80; 95% CI: 0.43-1.49).

“While our benefit did not last the entire school year, school IPM reduced asthma symptoms by 63% in the fall and winter when there is a high rate of seasonal exacerbations. It is interesting that while classroom HEPA filters reduced exposures, they did not improve health,” she told BreakingMED.

In addition, wrote Phipatanakul et al, “Despite the typical seasonal peaks in asthma symptoms during this time as demonstrated in the control group, the school-wide IPM program alleviated these symptoms. It is possible that the reduction in mouse allergens, while reducing irritants and exposures, also reduced the susceptibility to symptomatic viral wheezing illnesses that naturally peak during this period.”

In their accompanying editorial, William W. Busse, MD, and Daniel J. Jackson, MD, both of the Univesrity of Wisconsin, Madison, noted that “In 2000, as part of the National Cooperative Inner-City Asthma Study, Phipatanakul et al established a relationship between mouse allergen exposure and asthma disease activity in a study population of 499 children aged 4 to 13 years with asthma who attended inner-city schools in the northeastern U.S. Mouse allergen emerged as the dominant allergen detected in schools, with higher concentrations in school dust than in home dust (0.90 μg/g vs 0.14 μg/g; P<0.01).”

The value of this latest study from Phipatanakul and colleagues, they noted, is in the following:

“The study endorses the feasibility of using an allergen-rich school environment as a therapeutic target for asthma control, but perhaps benefit would occur if home allergen avoidance was also used to more fully eliminate the environmental allergen exposure. In addition, insights emerged for next steps to answer whether allergen avoidance is effective. Future efforts should more fully phenotype both the environment and study participants, and select environments with consistently higher concentrations of allergen exposure and children with greater levels of allergen sensitization and more symptomatic disease to allow for a greater likelihood of detecting a treatment effect.”

In reviewing these study results for BreakingMED, Jonathan A Bernstein, MD, FAAAAI, allergy specialist, Bernstein Allergy Group, Cincinnati, Ohio, noted, “Implementation of environmental control measures in the classroom and home is very challenging to improve asthma outcomes, as has been shown in multiple studies. It requires constant maintenance and monitoring of allergen levels to ensure they remain low and, as discussed in the editorial, there are multiple confounders such as viral respiratory infections and other allergic and non-allergic triggers that can impact asthma control.”

Despite the lack of significant findings, Bernstein noted that results of the post hoc analysis offered a glimmer of hope.

“A post hoc analysis revealed improvements in asthma symptom scores short term early in the school year that was not sustained into the school year likely because of viral infections and other confounders as well as difficulty maintaining IPM,” he told BreakingMED.

Nevertheless, Bernstein would “still recommend a multifaceted environmental control approach in the home and classroom to reduce exposure to indoor allergens but perhaps recommend investigating more effective whole room/building interventions than HEPAs.”

Study limitations include the possibility that IPM may have been insufficient—and “more aggressive and frequent booster visits may be required to sustain benefit,” possibility of decreases in IPM benefits with decreased viral illness-related asthma symptoms during the warmer months, limitations on dust sampling before necessary IPM booster visits due to school scheduling limitations, participating schools being more likely to undertake behavioral changes related to mouse infestation, and the lower classroom mouse dust allergen levels in these schools compared with observational school study (median levels: 0.17 versus 0.90 ug/g, respectively).

“Environmental studies are hard to do and conduct. We hoped that using similar methods that have been used successfully in homes could help a school environment, but there likely needs to be more resources and aggressive measures in a busy, open school environment. Further work is needed in this area,” Phipatanakul told BreakingMED.

1. Among children 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.

2. Two weeks after the intervention, the reduction in symptom days was significant, but this reduction was not sustained, and was significantly lower at 8 weeks and lower still at 20 weeks.

Liz Meszaros, Deputy Managing Editor, BreakingMED™

Cat ID: 100

Topic ID: 80,100,730,100,637,192,63,925