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.