DISCUSION
This secondary analysis of the CHAT data aimed at investigating the
effect of AT on recurrent wheezing in children with OSAS at the 7-month
follow up visit. Results showed that recurrent wheezing was no different
in children randomized to AT compared to those randomized to WWSC after
controlling for the following confounders: age, gender, race, parents
and siblings with asthma, exposure tobacco, siblings, AHI, BMI z-score,
maternal education, and family income.
The results of the present study, which is the first RCT of AT, were
similar to an adenoidectomy RCT previously conducted by Mattila et al.
in Finland [12]. They analyzed 166 children (aged 12–48 months)
with recurrent or persistent otitis media who were followed for 3 years
after randomization to undergo insertion of tympanostomy tubes with or
without adenoidectomy and showed that adenoidectomy did not influence
baseline lung function, exercise-induced bronchoconstriction, exhaled
nitric oxide concentration, the development of positive skin prick
tests, or physician-diagnosed asthma [12].
Those results were in contrast with several observational studies
performed in US. Saito et al. [7] found in 25 asthmatic children
that 88% of them improved their symptoms and reduced or eliminated the
need for asthma medications after AT. Busino et al. [8] compared 93
children with asthma and 372 without asthma who underwent AT mainly for
OSA/adenotonsillar hypertrophy and showed that the Asthma Control Test
(ACT) scores significantly improved 12 months following AT. Levin et al.
[9] conducted a retrospective cohort analysis of 66 children with
asthma and 64 controls and showed 6 months after AT that improvement in
the ACT in 85% of the asthmatic children. In a prospective cohort, 52
out of 92 children with poorly controlled asthma had OSA and after
1-year follow-up of 35 children who underwent AT due to OSA decreased
annual frequency of asthma exacerbation, rescue inhalers use, and asthma
symptoms compared to no changes in the group without OSA [14]. Also,
a large longitudinal cohort comparing asthma outcomes one year preceding
vs. one year following AT, showed that AT was associated with
significant reductions in asthma exacerbation, status and emergency
visits, hospitalization rate and asthma prescription, but no information
was available for race and obesity status [15]. Finally, a
systematic review suggested an overall reduction in asthma severity
following AT e.g., decline in the use of respiratory medications,
reduction in the frequency of asthma exacerbations, decrease in asthma
symptoms and in medication use and emergency department visits for
severe distress [16]. However, since several biases could affect
observational studies, we considered important to further analyze RCT
data. Both RCTs done in Finland [12] and CHAT showed no effect of
adenoidectomy or AT on asthma or wheezing, respectively.
This study has some limitations. First, the diagnosis of asthma was
assessed by questionnaires, and the available baseline and follow up
outcome were wheezing episodes. However, results did not change by
wheezing severity. Second, no pulmonary function tests, respiratory
medications use, decrease in asthma symptoms and emergency department
visits for severe distress were assessed and atopic markers were not
performed. Finally, follow up was limited to 7 months and since asthma
is a chronic condition, a larger follow up time may be required.
Nonetheless, CHAT is the largest AT RCT to date, most patients (more
than 90%) completed the study, and the effect of AT on wheezing was
controlled for several potential confounders.
Conclusions. This post-hoc analysis of the largest AT RCT demonstrated
that AT has not effect on wheezing at 7 months of follow-up.