DISCUSSION
There are only a limited number of studies, which focused on
environmental allergens, although the relevant literature reported the
importance of environmental factors on the variability in lung function
of the patients with CF.6,23 Previous studies
suggested that the prevalence of atopy in patients with CF was similar
to the general population.24,25 The ISAAC (The
International Study of Asthma and Allergies in Childhood) Phase II
study, which was conducted in Izmir, the prevalence of susceptibility to
at least one aeroallergen was 8.8% in 2112 school-age children based on
the SPT results.26 In the present study, there was
atopy in 33.3% of our patients with CF.
This is indicative of the fact
that the allergen susceptibility in children with CF is higher compared
to the healthy children in Turkish society. Furthermore, it was
suggested that environmental factors were more important regarding the
prevalence of atopy compared to the genetic
differences.6 In the present study, there was no
difference between the presence of atopy and CFTR gene mutations.
The patients susceptible to allergens had higher Total IgE levels,
higher rates of eosinophilia, and higher rates of ICS and SABA use.
There was no difference by bacterial colonization, FEV1predicted value, bronchiectasis, BMI, and MSK scores between SPT
positive and negative groups. Nevertheless, the prevalence of
bronchiectasis was higher and MSK scores were lower in patients
susceptible to AF. Patients with Pa colonization had a higher rate of
positive SPT results compared to non-colonized patients, with manifest
AF susceptibility. Nevertheless, there was no difference by Sa
colonization. This may suggest that certain infectious agents are
associated with atopy.
A study, which investigated 55 patients with CF in the adult population
associated the presence of atopy in CF with rhinitis
symptoms.27 However, the present study did not
identify any correlation between presence of atopy and AR. Based on the
results of the study, we suggest that the effect of AR on CF clinical
findings is not remarkable.
There was susceptibility to fungi (19.6%) followed by pollen (15.7%),
while the most prevalent was the AF susceptibility. It was reported that
35% of children with CF had susceptibility to AF, 25% to grass pollen,
and 13% to house dust mites.8 Relevant studies
suggested the association between susceptibility to AF and severe lung
disease.1,3,6,28 ABPA is defined as a clinical picture
that may result in chronic lung disease due to a sudden hypersensitivity
reaction to AF.20 It was reported that 31-59% of the
patients with CF were susceptible to AF and approximately 1-10%
of those patients had
ABPA.1,3 In the present study, there were clinical
findings suggesting ABPA in 3 patients susceptible to AF. There was
susceptibility to fungi in one case and to pollen in another case.
Although we had a small number of patients, we considered that
additional allergen susceptibility might have an effect on the
occurrence of ABPA. Relevant literature reported that atopy was an
important risk factor for the occurrence of ABPA and ABPA was more
prevalent in SPT positive individuals with CF, who were susceptible to
at least one aeroallergen other than AF.1,3
It was also reported that all the pulmonary function parameters,
including forced expiratory volume in 1 second (FEV1),
were lower in patients with ABPA, infected with Pa, and in atopic
individuals with CF.5 Certain studies suggested that
the effect of atopy on respiratory function was
insignificant.25 In the present study, there was no
significant difference between the FEV1 predicted value
and positive SPT results, eosinophilia, and ICS use. Whereas, the
FEV1 predictive value was significantly lower in
patients with bacterial colonization, bronchiectasis, and lower BMI.
Therefore, we considered that atopy had little effect on the respiratory
function in patients with CF. Nevertheless, the prevalence of bacterial
colonization and bronchiectasis was higher and MSK scores were lower in
our patients susceptible to AF. Therefore, we suggest that AF is
considered in patients with CF with severe clinical prognosis.
It is difficult to prove comorbid asthma in patients with CF. However,
the term ”CF asthma” was introduced for the patients with CF with airway
obstruction attacks responsive to bronchodilators, personal atopy
evidence, and eosinophilia. It was even suggested that the above
definition represented a different phenotype.29,30While certain studies argued that higher Total IgE levels and
eosinophilia might support the CF and asthma combination, other studies
disagreed.3,25,31 The Total IgE and eosinophil levels
were higher in our atopic CF patients. Nevertheless, we were able to
detect early reversibility in a very few patients by means of
spirometry.
Relevant studies in the literature reported that 88.2% of the patients
with CF used some sort of inhaled bronchodilator.29The rate of ICS prescription was reported as 10% in France, 12% in
Germany, and 36% in the United Kingdom.32 Although
the ICS use is frequent in patients with CF, relevant studies found
inconsistent results as regards the effects of ICS use on
FEV1.33-35 The rate of ICS use was
39.2% in our patients. The prevalence of positive SPT results
significantly higher in patients using ICS compared to those who did not
use ICS, and the Total IgE levels were significantly higher. However,
there was no difference by the FEV1 predicted values and
MSK scores. Similarly, there was no significant difference by
FEV1 predicted value and MSK score between atopic and
nonatopic groups using ICS. Obviously, we believe that extensive studies
are needed to assess the effectiveness of and requirement for ICS
treatment in CF cases.
A Turkish study, which investigated 54 patients with CF, reported that
the mean MSK scores of the patients aged between 6 and 22 years was
71±18.7, where the mean BMI was 17.8±3.57. Furthermore, it was
demonstrated that there was a strong positive correlation between
FEV1 and MSK score (r=0.778,
p<0.01).15 Another study reported that there
was a weak correlation between the pulmonary function and BMI in
children with CF (r = 0.52, p <0.001).36
The mean MSK score of our patients was 72.54±11.50, where the mean BMI
was 17.47±3.09. The patients’ MSK scores were moderately correlated with
FEV1 predicted value and weakly correlated with BMI.
Furthermore, the FEV1 predicted values were moderately
correlated with BMI.
Our study is based on the data collected from our clinic; the number of
patients is limited and does not represent the total population of the
patients with CF.
In conclusion; the importance of aeroallergens, which constitute an
important risk factor for asthma and account for a different phenotype,
is unclear as regards CF. Although the same may cause a new phenotype of
CF, their effect on prognosis seem unremarkable, except for the mold
allergens. Nevertheless, the relationship between CF and atopy should be
closely observed for the fact that atopy in patients with CF may mediate
the occurrence of ABPA. Furthermore, the individuals susceptible to AF
should be closely monitored for bacterial colonization, bronchiectasis,
ABPA, and poor clinical outcomes, regardless of other aeroallergens.
Identification of the population, in which the ICS treatment aimed to
prevent pulmonary exacerbation in CF may prove to be effective, may
prevent unnecessary drug use. Extensive studies to investigate this
topic will be useful.