Page 78 - Škrgat, Sabina, ed. 2022. Severe Asthma - Basic and Clinical Views. Koper: University of Primorska Press. Severe Asthma Forum, 1
P. 78
is necessary because positive test during the during pollen season and negative dur-
acute bronchitis episode and 4-6 weeks after ing wintertime; however, this is more an
severe asthma forum 1: severe asthma - basic and clinical views that could produce false positive result and exemption as a rule.
lead physician to false conclusion, that the pa- 2. Workplace-related asthma: the test
tient has asthma. Proper timing of the test is could be repeated if new-onset respira-
also important in elite sportsmen exercising tory symptoms appear in a patient work-
in cold environments (e.g., biathlon runners) ing in asthma-risk workplace; 3-5 years
and in diagnostic procedure of work-related after complete removal from workplace,
asthma. if test was positive (e.g., in retirement).1,8
BHR test has a high (over 95%) nega- Repeatability of the test in the same per-
tive predictive value – to exclude asthma. The son within a week is within two doubling con-
positive predictive value varies very much in centrations of the provoking agent. However,
relation to provocation dose of inhaled agent inter-laboratory repeatability can reach up to
and has over 50% of »false positives« in a 300% difference. That methodological issue
range above 2mg cumulative methacholine makes the interpretation of repeated test even
dose. Therefore, if the test is negative at the more difficult.
time when the patient has symptoms, we can
be sure that the patient does not have asthma. Bronchial Hyper Responsiveness
vs. Bronchial Reversibility
BHR is linked to different genetic loci
on our chromosomes as is atopy. Current ev- Those terms could not be used interchange-
idence suggests, that BHR has two compo- ably since they do not necessary represent
nents: »inducible« – linked to the level of air- the same process within the airways. How-
way inflammation (due to either IgE-mediated ever, many epidemiological studies, looking
and/or neutrophilic-mediated) and »constitu- for population-based bronchial hyper respon-
tive« – linked to the level of airway remode- siveness have used a significant BD response
ling, hypertrophy of bronchial smooth mus- as a surrogate marker of BHR. Therefore,
cles and intrinsic properties of smooth muscle large population cohort data are hard to in-
cell. In that concept, it is understandable, that terpret. Some patients can have a positive BD
the first part of BHR could be diminished or test (defined by increase in FEV1 over 12%
even abolished by proper anti-inflammato- and 200mL) and negative broncho provoca-
ry treatment of airway mucosa and the sec- tion test, while other with documented BHR
ond being more inaccessible to treatment. In could have negative BD response (e.g., COPD
most of asthmatic patients their BHR exists patients). As already stated, both BD response
over the entire lifetime, even though the level as BHR are dynamically changing variables
of BHR may vary significantly and is linked over time, depending both on underlying air-
to expression of their symptoms. way inflammation and structural changes.
Repeated test for BHR is not useful in Structural Changes in Airways Linked
clinical practice. If the first test is done in a to BHR
proper time, its positive value can be consid-
ered significant. Repeated BHR is also not Airway Smooth Muscle (ASM)
recommended to assess the success of medical
treatment (e.g., inhalation drugs for asthma). Human studies in alternations of airway
However, the test could be repeated in certain smooth muscle function require bronchial bi-
circumstances: opsy and are therefore limited. However, ep-
ithelial damage of any kind can result in al-
1. Periodic asthma (allergen driven sea- tered smooth muscle function and thickening
sonal asthma): the test could be positive
acute bronchitis episode and 4-6 weeks after ing wintertime; however, this is more an
severe asthma forum 1: severe asthma - basic and clinical views that could produce false positive result and exemption as a rule.
lead physician to false conclusion, that the pa- 2. Workplace-related asthma: the test
tient has asthma. Proper timing of the test is could be repeated if new-onset respira-
also important in elite sportsmen exercising tory symptoms appear in a patient work-
in cold environments (e.g., biathlon runners) ing in asthma-risk workplace; 3-5 years
and in diagnostic procedure of work-related after complete removal from workplace,
asthma. if test was positive (e.g., in retirement).1,8
BHR test has a high (over 95%) nega- Repeatability of the test in the same per-
tive predictive value – to exclude asthma. The son within a week is within two doubling con-
positive predictive value varies very much in centrations of the provoking agent. However,
relation to provocation dose of inhaled agent inter-laboratory repeatability can reach up to
and has over 50% of »false positives« in a 300% difference. That methodological issue
range above 2mg cumulative methacholine makes the interpretation of repeated test even
dose. Therefore, if the test is negative at the more difficult.
time when the patient has symptoms, we can
be sure that the patient does not have asthma. Bronchial Hyper Responsiveness
vs. Bronchial Reversibility
BHR is linked to different genetic loci
on our chromosomes as is atopy. Current ev- Those terms could not be used interchange-
idence suggests, that BHR has two compo- ably since they do not necessary represent
nents: »inducible« – linked to the level of air- the same process within the airways. How-
way inflammation (due to either IgE-mediated ever, many epidemiological studies, looking
and/or neutrophilic-mediated) and »constitu- for population-based bronchial hyper respon-
tive« – linked to the level of airway remode- siveness have used a significant BD response
ling, hypertrophy of bronchial smooth mus- as a surrogate marker of BHR. Therefore,
cles and intrinsic properties of smooth muscle large population cohort data are hard to in-
cell. In that concept, it is understandable, that terpret. Some patients can have a positive BD
the first part of BHR could be diminished or test (defined by increase in FEV1 over 12%
even abolished by proper anti-inflammato- and 200mL) and negative broncho provoca-
ry treatment of airway mucosa and the sec- tion test, while other with documented BHR
ond being more inaccessible to treatment. In could have negative BD response (e.g., COPD
most of asthmatic patients their BHR exists patients). As already stated, both BD response
over the entire lifetime, even though the level as BHR are dynamically changing variables
of BHR may vary significantly and is linked over time, depending both on underlying air-
to expression of their symptoms. way inflammation and structural changes.
Repeated test for BHR is not useful in Structural Changes in Airways Linked
clinical practice. If the first test is done in a to BHR
proper time, its positive value can be consid-
ered significant. Repeated BHR is also not Airway Smooth Muscle (ASM)
recommended to assess the success of medical
treatment (e.g., inhalation drugs for asthma). Human studies in alternations of airway
However, the test could be repeated in certain smooth muscle function require bronchial bi-
circumstances: opsy and are therefore limited. However, ep-
ithelial damage of any kind can result in al-
1. Periodic asthma (allergen driven sea- tered smooth muscle function and thickening
sonal asthma): the test could be positive
