Asthma and Indoor-air: Reducing Exposures

Study Overview
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Brief Summary
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Two hundred moderate to severely asthmatic children (6-12 years) will be enrolled in a study to look at the effectiveness of high efficiency filtration of indoor air in homes on reducing asthma symptoms. One intervention group will have high efficiency filters or filtration systems installed in their central heating and air conditioning (HVAC) system. The second intervention group will have high efficiency portable air cleaners placed in the child's bedroom and in the main living area. Each participant will receive true air filtration for a year and a placebo for a year. During the placebo period a sham filter will be used that removes very little of the particles. Measures of health effects will include days of symptoms, unplanned utilization of the healthcare system for asthma-related illness, short-term medication use, peak exhaled flow, spirometry, and exhaled nitric oxide (eNO).

Official Title
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Benefits of High Efficiency Filtration to Children With Asthma

Conditions
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Asthma

Intervention / Treatment
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* Other: Stand Alone Air Cleaner
* Other: HVAC Modification


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 6-12 years of age Living in Fresno, San Bernardino or Riverside Counties. Physician diagnosed asthma, as stated by the participant's caregiver. In the last six months, the child must have had asthma symptoms at least twice a week for several weeks in a row. Exclusion Criteria: Children living in homes where more than 2 cigarettes are smoked per week in the home. Children that spend 2 or more nights per week in another home. Children living in homes that are planning on moving in the next 2 years. Children living in homes that keep their windows open most of the time. Children living in homes that have existing high efficiency filtration.

Ages Eligible for Study
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Minimum Age: 6 Years
Maximum Age: 12 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Stand Alone Air Cleaner-True/Sham<br>The participant will have stand alone air cleaners placed in their home. They will have true filtration followed by sham filtration. | Other: Stand Alone Air Cleaner<br>* This is an environmental intervention using a stand alone air cleaner designed to reduce the air pollution levels in the home.<br>|
| Experimental: Stand Alone Air Cleaner-Sham/True<br>Participants will have stand alone air cleaners placed in their homes. They will begin with sham filtration. | Other: Stand Alone Air Cleaner<br>* This is an environmental intervention using a stand alone air cleaner designed to reduce the air pollution levels in the home.<br>|
| Experimental: HVAC modification-True/Sham<br>Participants will have their HVAC system modified to include high efficiency filtration. They will begin true filtration followed by sham filtration. | Other: HVAC Modification<br>* This is an environmental intervention that modifies the home HVAC system to include high efficiency air filtration designed to reduce the air pollution levels in the home.<br>|
| Experimental: HVAC Modification-Sham/True<br>Participants will have their HVAC system modified to include high efficiency filtration. They will begin sham filtration. | Other: HVAC Modification<br>* This is an environmental intervention that modifies the home HVAC system to include high efficiency air filtration designed to reduce the air pollution levels in the home.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Days with asthma symptoms | The maximum number of days with symptoms, from a two-week recall period, will be determined every three months. The maximum number of days with symptoms will be defined as the largest value among the following three variables: (i) number of days with wheezing, tightness in the chest, or cough because of asthma, (ii) number of days that the child had to slow down or stop his/her play or activities because of asthma, wheezing or tightness in the chest, or cough, or (iii) number of nights that the child woke up because of asthma, wheezing or tightness in the chest, or cough. The seasonally adjusted mean difference in the number of symptom days between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 3, 6, 9, 12, 15, 18, 21, and 24 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Forced expiratory volume at one second, percent predicted (FEV1 % predicted) | Lung function will be assessed using FEV1 % predicted. The adjusted mean difference in the FEV1% predicted between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 12 months and 24 months | 
| Forced vital capacity, percent predicted (FVC % predicted) | Lung function will be assessed using FVC % predicted. The adjusted mean difference in the FVC% predicted between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 12 months and 24 months | 
| Peak Expiratory Flow Rate (PEFR) | Lung function will be assessed using morning peak expiratory flow rate (PEFR), averaged for all days over one-week testing periods. The seasonally adjusted mean difference in the PERF measure between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 3, 6, 9, 12, 15, 18, 21, and 24 months | 
| Exhaled NO | The seasonally adjusted mean difference in the Exhaled NO between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measure at 6, 12, 18, and 24 months | 
| Days of missing school due to asthma | Days of missing school due to asthma will be expressed as a proportion of days of missing school versus the total number of school days during a two-week period. The seasonally adjusted mean difference in the proportion of missed school days between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 3, 6, 9, 12, 15, 18, 21, and 24 months | 
| Days of missing work for parents due to child's asthma | Days of missing work due to child's asthma will be expressed as a proportion of days of missing work versus the total number of work days during a two-week period. The seasonally adjusted mean difference in the proportion of missed work days between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 3, 6, 9, 12, 15, 18, 21, and 24 months | 
| Hospitalizations | The number of overnight hospitalizations due to asthma will be assessed every 3 months during real and sham periods. Participants will report number of overnight hospitalizations due to asthma that occurred in the previous three months. The adjusted mean hospitalization incidence ratio between the true and sham filtration periods will be compared using mixed-effects Poison regression models. | Count during 1-year true filtration period and count during 1-year sham filtration period | 
| Emergency Room Visits | The number of emergency room visits due to asthma will be assessed every 3 months during real and sham periods. Participants will report number of emergency room visits due to asthma that occurred in the previous three months. The adjusted mean emergency room visit incidence ratio between the true and sham filtration periods will be compared using generalized mixed-effects regression models. | Count during 1-year true filtration period and count during 1-year sham filtration period | 
| Unplanned Clinic Visits | The number of unplanned clinic visits due to asthma will be assessed every 3 months during real and sham periods. Participants will report number of unplanned clinic visits due to asthma that occurred in the previous three months. The adjusted mean unplanned clinic visit incidence ratio between the true and sham filtration periods will be compared using generalized mixed-effects regression models. | Count during 1-year true filtration period and count during 1-year sham filtration period | 
| Unplanned Steroid treatments | The number of unplanned steroid treatments due to asthma will be assessed every 3 months during real and sham periods. Participants will report number of unplanned steroid treatments due to asthma that occurred in the previous three months. The adjusted mean unplanned steroid treatment incidence ratio between the true and sham filtration periods will be compared using generalized mixed-effects regression models. | Count during 1-year true filtration period and count during 1-year sham filtration period | 
| Mini Pediatric Asthma Quality of Life Questionnaire (MiniPAQLQ) | The MiniPAQLQ has three composite domains, symptoms, emotional function, and activity limitation, each of which will be analyzed separately. The seasonally adjusted mean difference in each domain score between the true and sham filtration periods will be estimated using generalized linear mixed-effects regression models. | Measured at 3, 6, 9, 12, 15, 18, 21, and 24 months | 
| Allergy symptoms | Allergy symptoms during two week recall periods will be summarized into a composite score. The seasonally adjusted mean difference in the scores between the true and sham filtration periods will be using generalized linear mixed-effects regression models. | Measured at 3, 6, 9, 12, 15, 18, 21, and 24 months | 
| Respiratory disease | The number of incidents of respiratory disease will be assessed every 3 months during real and sham periods. Participants will report number of incidents of respiratory disease that occurred in the previous three months. The adjusted mean respiratory disease incidence ratio between the true and sham filtration periods will be compared using generalized mixed-effects regression models. | Count of incidents of respiratory disease during 1-year true filtration period and count during 1-year sham filtration period |