# Validation of a Useful Tool for Screening for Overweight and Obesity in Pre-Adolescents
## 4 Discussion  
During the childhood period, there are differences in growth and development between boys and girls, where many changes are observed. Boys begin the onset of puberty from 10 to 15 years of age, while girls begin from 8 to 13 years of age [27], but without evidence of any statistically significant difference in body fat percentage between the sexes [28].  
There is much scientific evidence that suggests that there are differences in many respects, in relation to a school, about sex. Focusing attention on the possible differentiation of the value of MUAC on sex for the screening for overweight and obesity in childhood, the MUAC measure has generally been used as a tool for screening for undernutrition [29; 30], however, there are studies that suggest the possibility of using MUAC for the follow-up of overweight and obesity in public health, as well as a tool to identify children and adolescents who require further evaluation or management of comorbidities [19; 31; 32].  
On the other hand, another study conducted on 5358 Turkish students aged 6 to 17 years, with the same objective as the present study, gave an MUAC value between 19.9 cm and 22.6 cm according to age and sex for students aged 10 to 12 years. This study obtained a value of the area under the curve of (AUC) 0.91, i.e., a high predictive value [31]. In the present study the AUC value was 0.96. This difference may be due to the larger age range studied in the Turkish sample; although this value is above AUC = 85, it has a high predictive value. Comparing the results of the two studies, it is observed that the MUAC cut-off values obtained in the Turkish study do not coincide with the values obtained in this study, although it is observed that the cut-off values are different depending on the age and sex of the participants.  
In another comparative study carried out with Argentinean and American samples, 22,736 schoolchildren aged 4 to 14 years were analysed, measuring the brachial perimeter with a tape measure and MUAC tape, and differences were observed between them based on these anthropometric measurements. Thus, in this study, it was observed that the MUAC value increased progressively with age, as in our study [33].  
Studies have also been undertaken in which the measurement of brachial perimeter is used as a screening tool for excess body fat in the paediatric population, where significant differences also appear between values by sex and course [34; 35]. Moreover, it is possible to carry out a nutritional diagnosis beyond the classic parameters such as BMI, intake, albumin, etc., and focus a new vision for a more precise, simple and rapid nutritional diagnosis that can be more sensitive and specific for nutritional diagnoses [18].  
The overweight model has a sensitivity of 91.5% and a specificity of 86.4%, and the obesity model has a sensitivity of 97.3% and a specificity of 81.5%. Both values are very high, which means that these models are highly suitable for screening for childhood overweight and obesity. Furthermore, the AUC exceeded 0.85 for overweight (AUC = 0.96) and obesity (AUC = 0.96), and the statistical model was significant and very good. However, future studies with a representative sample would be necessary for a final validation.  
As for the limitations of the study, the main ones were the adherence of the participating schools and families. As far as schools are concerned, it takes a lot of time and repeated efforts to get the school to participate in the study. Another point to be taken into account  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Course** & **Female** & **Male** \\ \hline
4 th & 23.14 & 22.30 \\
5 th & 23.68 & 22.84 \\
6 th & 24.54 & 23.71 \\ \hline \hline \end{tabular} Values in centimetres.  
\end{table}
Table 4: Cut-off values for mid-upper arm circumference for children with obesity by course and sex.  
is the adherence of the students, as some did not give informed consent to the parents, or the loss of documents was observed, or the parents ignored it completely.