Reply to Letter to: Reference values of waist circumference and waist/hip ratio in children and adolescents of Mérida, Venezuela: Comparison with international references

Sir,

We have carefully read the comments in the letter to the editor on our recently published article.¹ The study was indeed conducted in Municipio Libertador of the state of Mérida, as stated in the Materials and Methods section, and was part of a project called “Assessment of growth, development, and cardiometabolico risk factors in schoolchildren and adolescents of Mérida, Venezuela (CREDEFAR)”. We agree with the comments in the letter to the editor that any confusion should be avoided from the start of any article. This recommendation will therefore be taken into account, and the title of future CREDEFAR reports will state that data were collected in Municipio Libertador, Mérida, Venezuela.

Our study was observational and cross-sectional. We confirm that both the educational centers and the schoolchildren and adolescents participating were randomly selected following a rigorous plan, as stated in the article: “The sample was selected using proportional stratified, multistage random sampling that guaranteed adequate participation by sex, public or private institution (socioeconomic level), and geographical location”. The study population consisted of approximately 4000 children and adolescents for each year of age, in accordance with information provided by the educational area of the state of Mérida. As regards sample size, this was estimated based on the mean waist circumference of 58 cm and a standard deviation of 10 cm, as measured in a prior study conducted in our city,² with an alpha error of 5%, a beta error of 20%, a 2% precision, and an a priori power of 80%. Sample size was 94 participants per year of age, i.e. a total of 846 children and adolescents aged 9 to 17 years. This sample size was exceeded, as 919 students were enrolled into our study. Post hoc power was 96.63%. Calculations were also made to ensure that this sample size was adequate to obtain reference values of other anthropometric, clinical, and biochemical measurements, which will be reported soon. As in other publications,^3–5 such detailed information was not included in the article. However, it was reported in detail in the work project submitted for evaluation to funding agencies, both academic (Consejo de Desarrollo Científico, Humanístico, Tecnológico y del Arte de la Universidad de Los Andes-CDCHTA-ULA) and governmental (Fondo Nacional de Ciencia, Tecnología e Innovación del Ministerio del Poder Popular para la Ciencia, Tecnología e Innovación-FONACIT-MCTI).

The article recommends the use of our references at regional level, because they come from a population in Mérida, in the Andes region, and although some differences exist in its population, our references are undoubtedly closer to reality than those used to date, coming from other countries⁶ where the population is clearly different. As stated in the letter to the editor, national references are available in Venezuela for the vast majority of anthropometric variables, although references for waist circumference are not available yet.

Unfortunately, the literature review made could not find the reference of Hidalgo et al. reference⁷ entitled Measurement of cut-off points for waist circumference through ROC curves in pediatric population from three Venezuelan regions assessed at the SENACREDH referred to in the letter to the editor, which would have been worth discussing in our study. This journal has a year's delay in its publications, and was therefore not available at the time of writing our study. It should be noted that as of the current date, October 2013, the most recent number available is the one issued in October 2012.

We hope that the questions posed have been clarified. Research should be stimulated, particularly in training young people. The more that studies of this type, adequately and responsibly designed, are conducted, the greater the knowledge obtained about the behavior of the different anthropometric, clinical, and biochemical variables in our population, so allowing for the establishing of potential differences between the different geographic areas.