AIRWEIGHS: Investigating Obesity as a Susceptibility Factor for Air Pollution in Childhood Asthma

Johns Hopkins University

Status: Active, not recruiting

Conditions: Asthma

Treatments: Device: Placebo Air Purifier; Device: Active Air Purifier

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT02763917

IRB00074171

P50ES018176 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

Background: Asthma and obesity are public health crises that have concurrently risen over the past decades, affecting millions of children in the United States and disproportionately affecting low-income minority children in urban areas. The same children at highest risk for asthma and obesity also have greater exposure to indoor and outdoor pollution. Emerging evidence suggests that obesity may confer increased susceptibility to health effects of air pollution.

Methods: Aiming to provide causal-level evidence of these observational findings, we propose a home intervention study to 1) test whether targeted reductions of indoor Particulate Matter (PM) concentrations improve the respiratory health of overweight inner-city children with asthma more than that of lean inner-city children with asthma and 2) investigate mediators of susceptibility to indoor PM among overweight versus lean children with asthma. We will accomplish these aims using a 1:1 randomized controlled trial of 200 children with persistent asthma (half normal weight, half overweight) living in Baltimore City. Participants will be randomized to receive either two active air purifiers containing high-efficiency particulate air (HEPA) filters or two sham air purifiers with their filters removed.

Implications: If the aforementioned observational findings are confirmed, implications will be directly relevant to the over 170 million children around the world now estimated to be overweight or obese.

Full description

The primary object of this study is to determine the efficacy of a targeted environmental intervention among overweight inner city children as compared to normal weight inner city children with asthma.

Specific Aim #1: To determine if overweight inner-city children, compared to lean inner-city children, have greater improvement in asthma with an air purifier intervention aimed at reducing indoor PM.

Hypothesis 1: An intervention using HEPA filter air purifiers in the homes of inner-city children with asthma will be associated with greater respiratory improvement in overweight children than in normal weight children.

Specific Aim #2a: To investigate mediators of susceptibility among overweight versus normal weight children with asthma.

Hypothesis #2. Candidate mediators, including increases in a) tidal volume and thereby increases in doses of inhaled particles, b) inflammatory and oxidative stress responses, c) corticosteroid resistance, and d) sleep disordered breathing mediate increased susceptibility to indoor PM among overweight versus normal weight children with asthma.

Children with asthma will be enrolled in the study for about 16 weeks. They will have three clinic visits, an overnight sleep study, and two home environmental assessments for one week each. They will have a home and clinical assessment before randomization and another home and clinical assessment about 12 weeks after randomization. The primary outcome measure is maximum number of asthma symptom days.

Enrollment: 198 patients

Sex: All

Ages: 8 to 17 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. 8-17 years of age
2. Persistent asthma (NAEPP criteria)
3. Exacerbation in previous 12 months
4. Non-smoker
5. Spends ≥4 nights/week at home
6. No plans to move during the study

Exclusion criteria

1. Significant pulmonary or cardiac disease
2. Home not appropriate candidate due to disrepair
3. Underweight, defined by BMI <5th percentile
4. Pregnancy

Trial design

Primary purpose: Other

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Quadruple Blind

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198 participants in 2 patient groups, including a placebo group

Active Air Purifier

Active Comparator group

Description:

Two portable air purifiers containing HEPA filters will be placed in the bedroom and room where the participant reports spending the most time. We have chosen to deploy two air purifiers because we have observed a 50% reduction in indoor PM concentrations with two air purifiers. Participants will be instructed to run the air purifiers continually. Participants will receive educational materials about environmental factors that are important for asthma health and environmental modification strategies. Participants will also receive educational materials about health benefits of maintaining a normal weight.

Treatment:

Device: Active Air Purifier

Placebo Air Purifier

Placebo Comparator group

Description:

Homes in the control group will receive placebo air purifiers that have the internal air filters removed, but which will run normally. Participants will receive educational materials about environmental factors that are important for asthma health and environmental modification strategies, and educational materials about health benefits of maintaining a normal weight. At the end of the study, participants in the control group will receive active air purifiers. A control group is needed to ensure that reduced pollutant levels and health effects are not due to temporal trends and 'placebo effects' of being enrolled in an intervention trial. Participants will also be informed that being in the study does not prevent them from purchasing and using air cleaners during the study period.

Treatment:

Device: Placebo Air Purifier