The American Thoracic Society (ATS) has developed criteria for determining the level of impairment experienced by a patient with asthma. This can be used to monitor a patient and to evaluate the response to interventions.
Parameters:
(1) post-bronchodilator FEV1 relative to predicted value
(2) change in FEV1 (reversibility) OR airway hyperresponsiveness
(3) minimum medication needed
|
Parameter |
Finding |
Points |
|
post-bronchodilator FEV1 |
> lower limit of normal |
0 |
|
|
70% to lower limit of normal |
1 |
|
|
60 – 69% |
2 |
|
|
50 – 59% |
3 |
|
|
< 50% |
4 |
|
reversibility of FEV1 OR airway hyperresponsiveness |
FEV1 change < 10%, OR PC20 > 8 mg/mL |
0 |
|
|
FEV1 change 10 - 19%, OR PC20 0.51 to 8 mg/mL |
1 |
|
|
FEV1 change 20 - 29%, OR PC20 0.126 to 0.50 mg/mL |
2 |
|
|
FEV1 change >= 30%, OR PC20 <= 0.125 mg/mL |
3 |
|
minimum medication |
none |
0 |
|
|
occasional bronchodilator, not daily; occasional cromolyn, not daily |
1 |
|
|
daily bronchodilator; daily cromolyn; low dose inhaled steroid |
2 |
|
|
bronchodilator on demand and daily high dose inhaled steroid or occasional course of systemic steroids |
3 |
|
|
bronchodilator on demand and daily high dose inhaled steroid and daily systemic steroids |
4 |
where:
• Low dose inhaled steroid is < 800 µg beclomethasone or equivalent.
• High dose inhaled steroid is >= 800 µg beclomethasone or equivalent.
• Occasional course of systemic steroids involves 1 to 3 courses per year.
• percent FEV1 change = 100% * (((FEV1 post-bronchodilator) / (FEV1 prebronchodilator)) – 1)
• The calculation for PC20 (as a measure of airway responsiveness to methacholine or histamine) is given in the pulmonary chapter.
impairment score =
= SUM(points for the 3 parameters)
Interpretation:
• minimum score: 0
• maximum score: 11
|
Score |
Impairment Class |
|
0 |
0 |
|
1, 2 or 3 |
I |
|
4, 5 or 6 |
II |
|
7, 8, or 9 |
III |
|
10 or 11 |
IV |
|
asthma not controlled despite maximal treatment |
V |
where:
• Asthma not controlled despite maximal treatment = FEV1 < 50% despite prednisone dosing at >= 20 mg/day.
Purpose: To use the American Thoracic Society (ATS) criteria for impairment in a patient with asthma.
Specialty: Sports Medicine & Rehabilitation
Objective: risk factors, severity, prognosis, stage, selection, response to therapy, disability and performance
ICD-10: J45,
