Does RME reduce bedwetting?
There is an increasing interest in maxillary expansion for disordered breathing. It has been suggested that bedwetting is related to upper airway obstruction. As a result, expansion may be a potential treatment for bedwetting (nocturnal enuresis). This interesting new trial was done to look at this question. A team from Uppsala, Sweden did this study. The Angle Orthodontist published the paper.
What did they ask?
They did this trial to answer this question
“Was RME a useful treatment for bedwetting and can any prognostic variables be identified”?
What did they do?
They did a parallel-group randomised controlled trial with a 1:1 treatment allocation. The PICO was:
Children who were younger than 14 years with Nocturnal Enuresis (NE) with at least 7 wet nights out of 14. Most of the participants were non-responders to first-line treatments. They were classified as therapy-resistant. A paediatrician assessed all the children.
Tooth borne RME with a Hyrax screw designed to generate 0.5mm expansion per day. The endpoint of treatment was when the palatal cusp of the upper first molar came into contact with the buccal cusp of the lower first molar.
They fitted a placebo appliance identical to the RME appliance except it did not generate any expansion.
The primary outcome was the number of wet nights. Secondary outcomes were measures of expansion.
They took dental casts at the start of the expansion and after 6 months.
They used pre-determined computer-generated randomisation, with good concealment using remote allocation. This separated the recruitment and randomisation processes. The patients were blinded to the allocation. Their statistics were linear modelling and this was relevant.
What did they find?
They randomised 18 patients to each group. The mean age of the participants was 10.2 years in the control group and 10.3 years in the intervention group. Two dropped out of the control group.
In the expansion group, the mean expansion was 5.7 mm at the molars.
I have extracted the data on the number of wet nights into this table.
Number of wet nights over two weeks.
|RME||Control||RME Vs Control|
|T0 (mean and SD)||T1 (mean and SD)||Difference (95% CI)||T0 (mean and SD)||T1 mean and SD||Difference (95% CI)||Difference (95% CI)|
|11.4 (2.9)||9.2 (4.0)||-2.2 |
|12.4 (2.3)||11.7 (2.5)||-0.6 |
(-2. to 0-0.8)
(-3.6 to 0.4)
In summary, when they looked at the treatment group in isolation there was a statistically significant reduction in NE. They did not find this for the control group. However, when they compared the RME and the control group they found no significant differences in the episodes of NE between the groups.
Their overall conclusions were:
“RME has a modest effect on children with therapy-resistant nocturnal enuresis”.
What did I think?
I was very interested in this study because it was concerned with an outcome measure that is important to our patients. It was also great to see that they did not get bogged down in a mass of cephalometrics and dental measurements. They carried out and reported the study well and the paper was very clear. It was also great that they used a placebo as control and this meant that they had taken into the account any placebo effect. They clearly could not have left a group totally untreated. I liked the trial.
However, I hope that I have not looked at their data too critically. But, my interpretation is different from the authors. Their statistical analysis shows that there is no difference in NE between the RME and the control group. As a result, I cannot see how they could conclude that there was a modest effect of RME. While I concede that this may be my reliance on statistics and I may have missed something. I would be interested to hear what other readers, or the authors, think about the conclusions?
Emeritus Professor of Orthodontics, University of Manchester, UK.