Asthma
Conditions
Keywords
Exposure to Oxford Street, Exposure to Hyde Park
Brief summary
Acute exposure to diesel exhaust under normal city conditions leads to a worsening of symptoms of asthma, with reduction in lung function in asthmatic nonsmoking adults, dependent on the exposure dose and on the background severity of asthma. The worsening asthma is accompanied by increased oxidative stress and inflammation in the lungs.
Detailed description
The investigators will recruit 60 nonsmoking asthmatics of mild and of moderate severity. They will be exposed to Oxford St. or to Hyde Park for 2 hours each, at a walking pace. Real time exposure to PM2.5, carbon monoxide and nitrogen dioxide will be made each time. Health outcome measurements will be made before and after exposure to each street. Statistical analyses will be made to examine the effect of diesel exposure on changes in health outcome measures.
Interventions
OTHEROxford street
2 h walk around Oxford street
OTHERHyde park
2 h walk around Hyde park
Sponsors
Health Effects Institute
Imperial College London
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 55 Years
Healthy volunteers
No
Inclusion criteria
Subjects will be selected according to the current severity of their asthma; thirty from Steps 1 and 2 and thirty from Step 3 of the World Health Organization (WHO) Global Initiative for Asthma (GINA) asthma guidelines. These will include mild and moderate asthmatic states. Depending on baseline FEV1, subjects will undergo either a methacholine bronchial hyperresponsiveness assessment or airways reversibility testing. Subjects with normal FEV1 (\>80% predicted) or normal FEV1/FVC ratio will undergo methacholine challenge. Subjects with FEV1 \<80% predicted will undergo airways reversibility testing. Subjects must have either a PC20 of less than 8mg/ml methacholine, or improvement in FEV1 of 12% or more, following inhalation of short acting β-agonist (salbutamol 200μg from metered dose inhaler \[MDI\]). Skin prick testing will be conducted for common allergens (house dust mite, grass pollen, aspergillus fumigatus and cat hair). The results will only be for descriptive purposes, not as subject inclusion/
Exclusion criteria
. Subjects may be atopic or non-atopic (according to history and allergy testing).
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Spirometry, Percentage Change in FEV1 From Baseline | baseline, 24 hours after |
Participant flow
Pre-assignment details
Healthy volunteers were not recruited. Only asthma patients.
Participants by arm
| Arm | Count |
|---|---|
| Mild Asthma Asthma patients with mild asthma | 31 |
| Moderate Asthma Asthma patients with moderate asthma | 29 |
| Total | 60 |
Baseline characteristics
| Characteristic | Moderate Asthma | Total | Mild Asthma |
|---|---|---|---|
| Age, Continuous | 34 years | 32 years | 31 years |
| Race and Ethnicity Not Collected | — | 0 Participants | — |
| Region of Enrollment United Kingdom | 29 participants | 60 participants | 31 participants |
| Sex: Female, Male Female | 15 Participants | 29 Participants | 14 Participants |
| Sex: Female, Male Male | 14 Participants | 31 Participants | 17 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 31 | 0 / 31 | 0 / 29 | 0 / 29 |
| other Total, other adverse events | 0 / 31 | 0 / 31 | 0 / 29 | 0 / 29 |
| serious Total, serious adverse events | 0 / 31 | 0 / 31 | 0 / 29 | 0 / 29 |
Outcome results
Primary
Spirometry, Percentage Change in FEV1 From Baseline
Time frame: baseline, 24 hours after
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Mild Asthma Hyde Park | Spirometry, Percentage Change in FEV1 From Baseline | -1.0 percentage change in FEV1 from baseline |
| Mild Asthma Oxford Street | Spirometry, Percentage Change in FEV1 From Baseline | -4.8 percentage change in FEV1 from baseline |
| Moderate Asthma Hyde Park | Spirometry, Percentage Change in FEV1 From Baseline | -2.2 percentage change in FEV1 from baseline |
| Moderate Asthma Oxford Street | Spirometry, Percentage Change in FEV1 From Baseline | -7.4 percentage change in FEV1 from baseline |
p-value: <0.05t-test, 2 sided
p-value: >0.05t-test, 2 sided