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## Revista Paulista de Pediatria

##
*versão impressa* ISSN 0103-0582*versão On-line* ISSN 1984-0462

### Rev. paul. pediatr. vol.27 no.3 São Paulo set. 2009

#### http://dx.doi.org/10.1590/S0103-05822009000300003

**ORIGINAL
ARTICLE**

**Nutritional
status evaluation in schoolchildren according to three references**

**Roseane Moreira
S. Barbosa ^{I}; Eliane de Abreu Soares^{II}; Haydée Serrão
Lanzillotti^{III}**

^{I}Nutricionista
da Fundação Ataulpho de Paiva, doutoranda em Nutrição
da UFRJ, Rio de Janeiro, RJ, Brasil

^{II}Nutricionista, Doutora em Ciência dos Alimentos pela Universidade
de São Paulo (USP); professora associada do Instituto de Nutrição
da UFRJ; professora adjunta do Instituto de Nutrição da Universidade
do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, Brasil

^{III}Nutricionista; Doutora em Saúde Coletiva pela UERJ; professora
adjunta da UERJ, Rio de Janeiro, RJ, Brasil

**ABSTRACT**

**OBJECTIVE:**
To compare the nutritional status of schoolchildren according to three different
reference curves.

**METHODS:** The weight and height of 181 children aged 5-10 years were obtained
from a database for the nutritional surveillance of schoolchildren from Paquetá
Island, RJ, Brazil, which had been designed in compliance with recommendations
of the Brazilian Food and Nutrition Surveillance System (Sistema de Vigilância
Alimentar e Nutricional, Sisvan). Bland-Altman plot and deviation ratios were
used to produce profiles of agreement between pairs of nutritional assessment
references using body mass index values. Cutoff values of the following standards
were used in order to determine the prevalence of overweight and weight and
height deficit: Cole, Centers for Disease Control and Prevention (CDC), and
Conde & Monteiro.

**RESULTS:** The prevalence rates for obesity in girls were similar using
the Cole and Conde & Monteiro (3.1%) cutoffs, but the prevalence rate according
to the CDC standard was significantly lower (2.0%). For boys, the prevalence
of obesity using the Conde & Monteiro cutoff (4.8%) was lower than the rates
obtained using the cutoffs suggested by Cole (7.2%) and by the CDC (7.2%).

**CONCLUSIONS:** These results suggest that the choice of the Brazilian reference
curve (Conde & Monteiro) does not impair the comparison with other international
standards, particularly for obesity in male schoolchildren.

**Key words:**
Overweight, obesity, nutritional surveillance, child.

**Introduction**

Anthropometry is
an important diagnostic method both in clinical practice and in population studies,
providing estimates of the prevalence and severity of nutritional disorders.
Anthropometric assessment takes on great importance in the nutritional diagnosis
of children due to its ease of application, objectivity of measurements, and
the fact that it is possible to compare results against a reference standard
that is relatively simple to deal with, particularly in population studies^{(1)}.

Many different
references are used for the nutritional diagnosis of children. In 1977, the
National Center for Health Statistics (NCHS)^{(2)} published a set of
reference data for both sexes within the age group of zero to 18 years based
on weight-for-age (W/A), weight-for-height (W/H), length-for-age (L/A), height-for-age
(H/A), and head circumference-for-age (HC/A), and recommended their use within
the United States. Following their publication, the World Health Organization
(WHO) recognized the NCHS standard (1977)^{(2)} as appropriate for assessing
other racial groups and recommended it for international use. It was also adopted
by the Brazilian Ministry of Health^{(3)}.

Starting in 1985,
the NCHS^{(2)} growth charts that had been used worldwide since 1977
were revised with the objective of reflecting secular changes and correcting
and/or minimizing a series of failures that indicated that they were an imperfect
indicator of growth. All of the criticisms made to the NCHS/1977^{(2)}
were considered and analyzed in detail. In general, the main innovations were:
improvement of the statistical techniques; use of larger samples in order to
guarantee racial representativity and to reflect the ethnic diversity of the
American population; standardization of data collection methods; incorporation
of data from five American studies; extension of all of the curves up to the
age of 20 years; development of body mass index for age (BMI/age); publication
of the lower limits for length (45 *versus* 49 cm) and height (77 *versus*
90 cm); development of the third and 97^{th} percentiles for all curves
and of the 85^{th} percentile for the W/H and BMI/age curves. Furthermore,
data from the Fels^{(3)} study were eliminated from the weight and height
datasets because they had been primarily obtained from children fed on formula,
and it is known that the growth rate of these children is substantially different
from that of breastfed children during the first two years of life^{(4)}.
The new anthropometric reference standard was published by the Centers for Disease
Control and Prevention (CDC) in 2000^{(4)}.

Also in 2000, Cole
*et al*^{(5)} defined age- and sex-dependent BMI cutoff points
for children and adolescents to classify overweight and obesity. The dataset
used for that reference came from six studies that were representative of the
following countries: Brazil, Great Britain, Hong Kong, the Netherlands, and
the United States, including children and adolescents aged six to 18 years.
In that study, the authors established a relationship between adult cutoff points
and BMI percentiles for children with the objective of establishing cutoff points
for overweight and obesity for each age group. According to Cole *et al*^{(5)},
the BMI percentile curves were constructed using the LMS method (lambda, mu,
sigma), where M expresses the median value of the index observed within each
stratus, S represents the coefficient of variation of each stratus, and L is
the mathematical transformation coefficient (Box-Cox) applied to the BMI values
with the objective of obtaining a normal distribution within each stratus. The
curves for each parameter were smoothed using polynomials for each sex, making
it possible to establish cutoff points for BMI, overweight and obesity on the
basis of international data and these were then recommended by the International
Obesity Taskforce (IOTF)^{(6)}. In 2007 and using the same methodology,
Cole *et al*^{(6)} established age- and sex-dependent BMI cutoff
points for children and adolescents in order to classify underweight^{(6)}.

Recently, in 2006,
Conde and Monteiro^{(7)} published a reference system for assessing
the nutritional status of Brazilian children and adolescents. Their system was
based on BMI, included a reference curve, and established static and functional
critical limits for diagnosing underweight, overweight, and obesity. The dataset
used for these Brazilian BMI reference curves came from the National Health
and Nutrition Survey (Pesquisa Nacional Saúde e Nutrição)^{(8)},
carried out in 1989 by the Brazilian Institute of Geography and Statistics (Instituto
Brasileiro de Geografia e Estatística, IBGE)^{(8)}, and covered
children and adolescents aged two to 19 years. The method employed to produce
the Brazilian curves was basically the same as that used in the development
of international BMI standards^{(5)}.

The fact that existing
references for assessing the nutritional status of children are not interchangeable
demonstrates the need to perform investigations comparing these references.
Therefore, the objective of this study was to compare assessments of the nutritional
status of schoolchildren made using three different reference curves: CDC^{(4)},
Cole *et al*^{(5,6)} and Conde and Monteiro^{(7)}.

**Methods**

This study was approved by the Research Ethics Committee at Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro. The data needed to compare the references used to assess nutritional status (underweight, overweight and obesity) were obtained from a database employed in the nutritional surveillance of schoolchildren living on Paquetá Island, RJ, Brazil, designed according to the recommendations of the Food and Nutrition Surveillance System (Sistema de Vigilância Alimentar e Nutricional, Sisvan). The database contains the age, weight and height of 181 schoolchildren, 98 girls and 83 boys, aged five to 10 years.

The surveillance
project records revealed that weight (kg) was measured using a digital balance
(Plenna^{®}) with a capacity of 150kg and an accuracy of 0.1kg,
and that the children were wearing light clothing when weighed. Height (cm)
was measured using a measuring tape (in millimeters) fixed to the wall with
zero at ground level. Children were measured barefoot with nothing on their
heads and in an orthostatic position.

Weight and height
measurements were used to calculate the children's body mass index (BMI). Prevalence
rates were determined using the cutoff points recommended by the three reference
standards: CDC (2000)^{(4)}, Conde and Monteiro (2006)^{(7)},
and Cole *et al* ^{(5,6)}. The figures used by the CDC^{(4)}
to define underweight, overweight and obesity are BMI<5^{th} percentile,
BMI__>__85^{th} percentile and BMI__>__95^{th} percentile,
respectively. Conde and Monteiro^{(7)} used the following BMI values
as cutoff points: <17.5kg/m^{2} for underweight, __>__25kg/m^{2}
for overweight, and __>__30kg/m^{2} for obesity. Cole *et al*^{(5)}
used the same cutoff points for overweight and obesity as Conde and Monteiro^{(7)}.
However, in contrast to Conde and Monteiro, Cole *et al*^{(6)}
defined the cutoff point for underweight as <18.5kg/m^{2}.

When comparing
two methods, one common goal is to establish the degree of agreement between
them. Bland and Altman^{(9)} did not agree that a measure of correlation
could measure the degree of agreement between two methods and so they proposed
an alternative analysis. They suggested plotting the difference between measurements
provided by the two methods on the y-axis of a Cartesian graph and the means
of these measurements on the x-axis. Plotting the difference against the mean
allows to assess whether or not there is a relationship between the error of
the measurement and the true value. If there is no relationship between the
difference and the mean, the authors indicate the lack of agreement by calculating
the estimated divergence in terms of the mean difference () and the standard
deviation of the difference(s). It is expected that the majority of differences
will be within the interval between the mean difference () less 2 standard deviations
and the mean difference () plus 2 standard deviations, which are the limits
of agreement. If there is good agreement, the majority of points should be distributed
around the y-axis, where difference is 0. The precision of the estimated limits
of agreement is given by Student's *t* distribution, and the advantage
of the method is that it does not demand robust samples.

Delcourt *et
al*^{(10)} suggest that the agreement of nutritional assessment methods
should be verified using a standard deviation ratio, calculated by dividing
the standard deviation of the differences in BMI by the standard deviation of
the means of BMI, thereby producing a quantitative definition of the relative
agreement between methods. In this relationship, smaller ratios correspond to
a better agreement between the two methods.

Therefore, the
agreement profiles between pairs of nutritional assessment references were produced
using BMI values (weight/height^{2}). The descriptive statistical analysis
used frequency and range (CI - confidence interval), with significance set at
*p*<0.05. The inferential analysis used Bland-Altman^{(9)} measures
of agreement and deviation ratios^{(10)}.

**Results**

Table
1 shows that there was a statistically significant difference in the calculated
prevalence of obesity among the girls depending on the reference used, where
Cole *et al*^{(2)} and Conde and Monteiro^{(7)} resulted
in the same value (3.1%), which was greater than that obtained using the CDC^{(4)}
reference (2.0%). For the boys, the prevalence of obesity calculated using the
cutoff suggested by Conde and Monteiro^{(7)} (4.8%) was lower than the
percentage according to both Cole *et al*^{(5)} and the CDC^{(4)}
(7.2%).

The prevalence
of overweight was greatest according to Conde and Monteiro^{(7)} for
both girls and boys (not significant). Calculating the percentage difference
between results according to Conde and Monteiro^{(7)} and the other
two references, it was observed that obesity was more expressive for girls (5.1
and 8.2%, respectively) than for boys (2.4 and 3.6%, respectively).

A greater prevalence
of underweight for both sexes was observed using Cole *et al*^{(6)}
when compared with the other two references. It should be emphasized that there
was a significantly lower prevalence for both sexes (*p*=0.04) using Conde
and Monteiro^{(7)} when compared to the other two references. Figures
1 and 2 show the agreement
between pairs of references using the Bland and Altman method^{(9)}.
These results show that, for boys and girls, the points were displaced from
the zero difference axis, but did not pass the limits of agreement at ±2
standard deviations, with the exception of Conde and Monteiro *versus*
CDC for obesity in Figure 2
(boys).

Table
2 shows that the ratio of deviations was particularly low only for the obesity
classification in boys (0.04) when comparing Conde & Monteiro^{(7)}
with the CDC^{(4)}, whereas the ratio for Conde and Monteiro^{(7)}
*versus* Cole *et al* was 0.16^{(5)}. The ratios of deviations
for girls were 0.29 and 0.32. According to Delcourt *et al*^{(10)},
the lower the ratio, the better the relative agreement between the two methods.

**Discussion**

The main limitation of this study is the use of secondary data. Nevertheless, it should be pointed out that the techniques used to measure weight and height are routinely used in anthropometric assessment and are of easy access.

According to Conde
and Monteiro^{(7)}, using curves based on BMI/age to classify the nutritional
status of children and adolescents leads, on one hand, to practical solutions,
and on the other hand, to debates about the use of these curves to assess the
nutritional status of population groups in growth phases. The main point to
be taken into account is the universal or specific nature of body composition,
which is reflected in the discussion over the adoption of local or international
reference curves^{(11,12)}. Another aspect refers to the bases and properties
of classification systems based on BMI for age, which leads on to the debate
about the appropriateness of the use of statistical or epidemiological criteria^{(13)},
since the cutoff points that are the basis of BMI classifications are chosen
according to expected prevalence rates, thus making it possible for healthcare
management professionals to direct the distribution of available healthcare
resources to groups at nutritional risk. Finally, the influence of sexual maturity
on body composition and the need (or not) to take into account the stage of
sexual maturity should also be discussed^{(14,15)}.

The three references
used for nutritional assessment in the present study are different from one
another. We found a higher prevalence of overweight among schoolchildren (girls
19.4% and boys 10.8%) when the Conde and Monteiro curves were applied^{(7)}.
Similar findings were reported by Vitolo *et al*^{(16)} when they
assessed the prevalence of overweight and obesity among adolescents (n=418)
aged ten to 19 years using the reference curves by Cole *et al*^{(5)}
and Conde and Monteiro^{(7)}. They also found that the prevalence of
overweight was greater according to Conde and Monteiro (29% boys and 24.8% girls)
than according to Cole *et al*^{(5)} (27% boys and 19.3% girls),
with a greater percentage difference for the girls. According to Vitolo *et
al*^{(16)}, the reference published by Conde and Monteiro^{(7)}
showed greater sensitivity (83.3%) and positive predictive value (31.3%) than
the international reference. Cutoffs on the Brazilian reference showed greater
sensitivity for diagnosing excess adiposity among adolescents, reducing the
number of false-negative results.

A study by Sotelo
*et al*^{(17)} used WHO criteria (1995)^{(18)}, as well
as the reference curves published by Must *et al*^{(19)} and Cole
*et al*^{(5)}, to diagnose overweight and obesity in schoolchildren
aged six to nine years. They observed that the criteria suggested by Must *et
al*^{(19)} offered early diagnosis of anthropometric risk of obesity,
leading to overestimation of the prevalence in relation to WHO standards^{(18)},
whereas Cole *et al*^{(5)} underestimated the prevalence.

Another study carried
out by Bueno and Fisberg^{(20)} compared the prevalence of overweight
and obesity according to three reference standards (WHO, 1995^{(18)};
CDC, 2000^{(4)}; and Cole *et al*, 2000^{(5)}), in children
from two to seven years. They found prevalence rates of overweight of 18.6,
13.2, and 12.2% according to the WHO^{(18)}, CDC^{(4)}, and
Cole *et al*^{(5)} criteria, respectively. Among children aged
four to seven years, the difference was 2.3% for girls and 0.6% for boys. Our
study found percentage differences of 3.1 and 1.2% for girls and boys (Table
1). Bueno and Fisberg^{(20)} also calculated an agreement ratio
for the criteria, assessed using kappa statistics, and observed that it was
weaker for male overweight according to the CDC^{(4)} and Cole *et
al* criteria^{(5)}. It can be observed that the variety of references
for the diagnosis of nutritional status in children creates limitations and
difficulties for comparing the prevalence rates reported by several different
studies.

In our study, the
prevalence of underweight was greater according to Cole *et al*^{(6)},
probably as a result of the cutoff point chosen (BMI <18.5kg/m^{2}),
which is a diagnosis of grade 1 thinness. According to the authors, the cutoff
represents a -1 score, in contrast with the CDC^{(4)}, which classifies
underweight as <5^{th} percentile. A difference between the prevalence
of underweight was observed when Cole *et al*^{(5)} and the CDC^{(4)}
criteria were compared, reaching 5% for both sexes. In contrast, the prevalence
rates of underweight were the lowest according to Conde and Monteiro^{(7)},
although in their article these authors stress that the use of 17.5kg/m^{2}
as the critical value for weight deficit in children and adolescents requires
further analyses and wider discussion before its possible adoption.

Although the deviation
ratio for male obesity was low for the comparison between the Conde and Monteiro^{(7)}
and CDC^{(4)} references, it was not possible to detect any marked agreement
on the Cartesian graph, since the points were dispersed. As it may be observed,
these references are not interchangeable, and each one should be used in line
with the study objectives.

Classifications of nutritional status obtained using the references most commonly adopted in scientific circles and by health services can result in discrepancies in terms of prevalence rates. The choice of a procedure for the classification of nutritional status should be on the basis of the objectives of the study. There is no consensus on the validity of international references for developing countries, although the choice of a Brazilian reference does not appear to create difficulties for comparisons with international criteria, particularly with reference to the classification of obesity in male schoolchildren.

**References**

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2. NCHS (National Center for Health Statistics). Growth curves children birth - 18, United States. Washington: National Center for Health Statistics. DC: U.S. Printing Office; 1977. [ Links ]

3. Sontag LW. Biological and medical studies at the Samuel S. Fels Research Institute. Child Dev 1946;17:81-4. [ Links ]

4. Soares NT. Um novo referencial antropométrico de crescimento: significados e implicações. Rev Nutr 2003;16:93-104. [ Links ]

5. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000;320:1240-3. [ Links ]

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12. Piers LS, Rowley KG, Soares MJ, O´Dea K. Relation of adiposity and body fat distribution to body mass index in Australians of Aboriginal and European ancestry. Eur J Clin Nutr 2003;57:956-63. [ Links ]

13. Cole TJ, Roede MJ. Centiles of body mass index for Dutch children aged 0-20 years in 1980: a baseline to assess recent trends in obesity. Ann Hum Biol 1999;26:303-8. [ Links ]

14. Bini V, Celi F, Berioli MG, Bacosi ML, Stella P, Giglio P *et al*. Body mass index in children and adolescents according to age and pubertal stage. Eur J Clin Nutr 2000;54:214-8. [ Links ]

15. Wang Y. Is obesity associated with early sexual maturation? A comparison of the association in American boys versus girls. Pediatrics 2002;110:903-10. [ Links ]

16. Vitolo MR, Campagnolo PD, Barros ME, Gama CM, Lopez FA. Evaluation of two classiûcations for overweight among Brazilian adolescents. Rev Saude Publica 2007;41:653-6. [ Links ]

17. Sotelo YO, Colugnati FA, Taddei JA. Prevalência de sobrepeso e obesidade entre escolares da rede pública segundo três critérios de diagnóstico antropométrico. Cad Saude Publica 2004;20:233-40. [ Links ]

18. Organização Mundial de Saúde. WHO Expert Committee on Physical Status: the use and interpretation of anthropometry physical status: WHO technical report series, 854. Geneva: World Health Organization; 1995. [ Links ]

19. Must A, Dallal GE, Dietz WH. Reference data for obesity: 85th and 95th percentiles of body mass index (wt/ht2) and triceps skinfold thickness. Am J Clin Nutr 1991;53:839-46. [ Links ]

20. Bueno MB, Fisberg RM. Comparison of three overweight and obesity criteria among preschoolers. Rev Bras Saude Matern Infant 2006;6:411-7. [ Links ]

** Correspondence:**

Roseane Moreira
Sampaio Barbosa

Rua Visconde de Pirajá, 630/507 - Ipanema

CEP 22410-002 - Rio de Janeiro/RJ

E-mail: roseanesampaio@ig.com.br

Recebido em: 30/9/08

Aprovado em: 21/1/09

Institution: Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brasil