An interesting new trial looks at the efficacy of RME or adenotonsillectomy on childhood obstructive sleep apnoea.

Researchers are publishing an increasing number of trials on the treatment of paediatric obstructive sleep apnoea (OSA). These studies continue to contribute to the evidence regarding the role of orthodontics and/or adenotonsillectomy in managing this disorder. In previous posts, I have been critical of the quality of research conducted in this area. Therefore, I was very interested in this new trial.

One treatment proposed by those who advocate for the impact of orthodontic treatment on OSA is rapid maxillary expansion (RME). Unfortunately, the current evidence is derived from non-randomised studies. As a result, we need randomised trials to evaluate this form of treatment fully. This study is, therefore, timely.

A team from Bangkok, Thailand, did this study. The Sleep and Breathing journal published the paper.

What did they ask?

This study aims to 

“Demonstrate RME’s ability to improve apnea-hypoxia index and other polysomnographic (PSG) parameters and quality of life, particularly for those with maxillary constriction”.

What did they do?

The study team carried out a two-group parallel allocation RCT. The PICO was

Participants

Children aged between 4 and 10 years with an AHI of greater than 1 confirmed by PSG, with tonsillar and adenoid hypertrophy. They also had to have maxillary constriction with or without posterior dental crossbite.

Intervention 1

Rapid maxillary expansion. One board-certified orthodontist did this treatment. They asked the patients to activate the expander twice daily for 7 days, resulting in 7mm of expansion.

Intervention 2

Adenotonsillectomy. A board-certified ENT surgeon did this.

Outcome

The primary outcome was AHI, recorded at the start of the study and six months after treatment. They also documented several other relevant secondary outcomes.

They analysed the data using the relevant parametric and non-parametric analyses. The power calculation indicated that they needed to recruit 12 participants into each of the intervention groups.

What did they find?

All the participants completed the study. They had a mean age of 6.3 years, and 37% were female. The team presented a large amount of data, and I have decided to keep things simple by focusing on what I felt were the most important pieces of data.

At the start of the study, the median AHI for the participants was 7.0 per hour.  The mean Paediatric Sleep Questionnaire score was 0.62. This indicated significant clinical symptoms of OSA.

They reported that the participants had a narrow maxillary arch, compared to norms from a relevant population. However, they did not report this data.

There was no difference between the groups at the start of treatment.

The team reported on their data in several ways. I decided to examine the differences between the groups at the end of treatment, as this reports on the effect of the interventions.  

The median AHI for the adenotonsillectomy group was 1.4 with an interquartile range of 0.7-1.85. For the RME group, this was 2.3 (1.15-5.7) (<0.07)  

When they looked at the PSG score, the mean for the adenotonsillectomy group was 0.19 (SD=0.11), and for the RME group, it was 0.34 (SD=0.17; <0.01).

When they examined the cure rate (defined as AHI<1), it was 41.7% with the AT and 16.7% with RME (P<0.37).

Their conclusion was

“RME and adenotonsillectomy significantly improved sleep-related parameters in children with OSA. RME had similar efficacy to adenotonsillectomy in reducing AHI. However, AT provided significantly better improvement in clinical symptoms and quality of life”.

What did I think?

I want to begin this section by interpreting the data for AHI and PSQ. The AHI is measured by polysomnography, a standard test for OSA. In children, an AHI below one is considered normal. Mild obstructive sleep apnoea involves fewer than five events, moderate is 5-10 events, and severe is 10 or more events per hour. The results of this study indicate that median scores were higher than normal in both groups after treatment. Therefore, we cannot be certain that RME always resolves OSA.

The PSQ scores are derived from a questionnaire. Scores below 0.33 indicate a high risk of paediatric sleep-related breathing disorder. This implies that the RME group was at risk.

There was no significant difference in the cure rate for AHI between the groups. The difference was 25%. This is a marked difference, but it was not statistically significant. The authors suggested that this was due to a lack of power in the study. I suspect that this may be the case, and we should bear it in mind when interpreting the findings.

Unfortunately, they did not report the age of the participants at the end of the study. This is important because there were differences in the duration of the two interventions. The adenoidectomy treatment must have been shorter than the RME. As a result, the findings do not take into account the effects of growth differences between the groups.

Sample size

This brings me to the size of the study. This was a very small study, and although a sample size calculation was performed, it means there could be random variation in the results, which might influence the observed effect. Furthermore, the authors did not clearly explain how they calculated the sample size. They stated that this was done to calculate a sample based on AHI; however, they were unclear about the statistical test to be used. This is important because they measured other important outcomes, and the sample size calculation is not relevant to them.  As a result, the study may be underpowered. 

Absence of control group?

My other concern, apart from the sample size, is that the authors suggest that treatment affected OSA. Unfortunately, they cannot draw this conclusion because they did not enrol an untreated control group. As a result, the changes they report must include a component of normal growth. The study team explained that it was not possible to include a no-treatment group. Is this debatable, as it may be ethical to delay treatment for a group as an untreated control?

Indeed, this was demonstrated in this classic paper published in a highly influential journal. In fact, the authors of the current paper noted that the success rate of treatment with RME in their study was comparable to that previously reported for watchful waiting. This might address ethical concerns regarding delaying treatment.

We had a good discussion on this area in my previous blog post from 2024. This is worth revisiting.

Final comments

This paper is a good step in the right direction. I would like to congratulate the team on doing this study to attempt to answer a difficult question.  However, I have some doubts about the impact of a small study and its results. If this study were larger, the results would be more reliable and may provide us with important insights.  I wonder if those who promote orthodontic treatment for childhood breathing disorders would like to carry out this research?

Improving the quality and volume of research into this important subject area is necessary. Until this work is done, we must remember that adenoidectomy remains the primary treatment for paediatric OSA until more robust research evidence suggests alternatives.

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