Validity of a simplified screening instrument for assessing overweight children in a dental setting: a cross sectional study
© The Author(s). 2017
Received: 26 April 2016
Accepted: 7 February 2017
Published: 17 February 2017
Obesity, with its rising prevalence among Canadians and its estimated cost of $2 billion annually in Canada, is no longer considered a cosmetic issue, but a major health issue that imposes a great burden on the healthcare system and economy. This cross sectional study aims to evaluate the feasibility of identifying the weight status of 6 to 11 year-old children in a university dental clinic using a simplified overweight screening instrument.
One hundred sixty eight healthy children were enrolled. Weight and height were measured and overweight/obesity status was assessed using two techniques: 1) the 2007 World Health Organization Body Mass Index (BMI)-for-age reference Tables, 2) simplified overweight screening instrument without BMI calculation. Measures of overall, positive, and negative percent agreement between the two approaches were computed.
The children’s average weight, height, BMI and BMI z-score were respectively 32.6 ± 9.5 kg, 133.8 ± 10.7 cm, 17.8 ± 3.2, and 0.4 ± 1.0. The overall, positive, and negative percent agreement between the two screening approaches were respectively, 89%, 100%, and 83%.
This study demonstrated the feasibility and parental acceptance of weight, height and BMI measurement in a dental setting and evidence that supports the validity of a new simplified approach to assess children’s weight status without having to compute BMI.
NCT02637752. Registered 18 December 2015.
KeywordsChildhood obesity Child growth Weight BMI (Body mass Index)
The global prevalence of childhood obesity has increased at an alarming rate. In 2014, an estimated 41 million children under 5 years of age were affected by overweight or obesity, of which, almost three quarters are living in developing countries . Hence, obesity is no longer considered a cosmetic issue, but one of the most serious public health challenges of the 21st century , imposing a great burden on the health care system and economy . Therefore, screening children and identifying their overweight and obese status is important  as it leads to assessment of the associated comorbidities that occur at an earlier age and progress into adulthood . For example, both Canadian and U.S. clinical practice guidelines recommend that clinicians screen children at age six and older for overweight/obesity [3, 6, 7], and that for such children, weight-related diet and exercise counselling, provided by a multidisciplinary team, should be increased [6, 8].
The most common and practical method to assess obesity in children and adolescents is the Body Mass Index (BMI), the ratio of weight in kilograms to the square of height in meters [9, 10]. Obesity and overweight are defined through BMI-for age percentile plotting, with BMI from 85th to the 94th percentile considered overweight and BMI at or above 95th percentile considered obese for a specific age and gender . As simple as it sounds, the BMI-for age plotting is only used by half of the U.S. pediatricians and family physicians [12, 13]. Additional undertaking and ‘the cumbersome task’ of computing and assessing BMI from height and weight measurements in primary care settings have also been reported as a barrier to the BMI uptake [14–16]
Another group of health care providers with the potential to screen for childhood obesity is dentists. Given 1) the higher frequency of dental visits compared to medical visits (twice a year vs. once a year, especially during childhood) , and 2) the routine measurement of the children’s weight and height to calculate safe dosages of local anesthesia for most conscious sedation procedures or dental rehabilitation under general anesthesia, dentists, specifically pediatric dentists, have the potential to identify, assess and refer patients to appropriate resources . Yet, only less than 5% of U.S. pediatric and general dentists offer a form of obesity-related services , because mostly they lack training and knowledge for BMI computation and interpretation and guidelines [14, 17].
Recently, a simplified overweight screening instrument was developed based on data derived from the WHO 2007 Growth Reference that would use only the child's height and weight measurements without any additional computation. This simplified screening instrument was based on age- and gender-specific +1 standard deviation z-scores for the BMI, calculated for the various height percentiles at 6-month age intervals (from 5 to 19 years of age), and resulted in two simple tables, one for girls and one for boys that describe overweight screening values for height measurements for all 11 percentiles as described in the 2007 WHO Reference data . With the availability of this simplified approach, our study aims to evaluate the feasibility of identifying the weight status of 6 to 11 year-old children in a university dental clinic setting using either the 2007 WHO BMI-for-age tables or a simplified overweight screening instrument.
The cross sectional study refers to the baseline data of our recent randomized controlled clinical trial , conducted at the University of Toronto, Faculty of Dentistry from September 2011 to April 2014 (Trial Registration No. NCT02637752). The research protocol and its written informed consent were approved by the Research Ethics Board of the University of Toronto (Protocol No. 28052). The methodology was described in detail previously .
With BMI calculation: After a child’s height and weight were measured, BMI was computed as weight in kg/ (height in centimeters)2. The WHO BMI-for-age reference tables were consulted according to the gender of the individual. Then the child’s age was used to determine the tabular row recommended by WHO BMI-for-age reference tables. Any computed BMI value exceeding the ±1SD BMI Z-scores in the screening tabular row of the table was identified as overweight .
- 2)Without BMI calculation: Overweight status was also determined using a simplified screening instrument without any computation of BMI. This instrument, available from http://dx.doi.org/10.1038/oby.2011.159,  consists of two tables, one for girls (Additional file 1: Table S1) and one for boys (Additional file 1: Table S2). To ascertain the weight screening unit grid, the child’s age was selected in the tabular row(s) followed by the height for the tabular column(s). A child was identified as overweight if his/her weight exceeded the screening unit grid. An example is shown in Fig. 1.
Assuming a prevalence of unhealthy weight of 30% in the recruited sample, and using the goodness of fit tables , (with Kappa null value of 0.40, at two-tailed test null value = 0.40) the required sample size of n = 85 would satisfy a power of 80%. The sample size was increased to 168 to satisfy the primary outcome of the larger randomized clinical trial as outlined previously . Data were managed and analyzed using SAS 9.2 software (SAS Institute Inc., Cary, NC, USA). Descriptive analyses were performed using Chi-square test or student t-test as indicated. A 2x2 table of results comparing the two approaches for assessing overweight/obesity status were constructed and measures of overall, and positive and negative percent agreement were computed [26, 27]. Statistical tests were two-tailed and interpreted at the 5% significant level.
Descriptive characteristics of the study participants
Age in months (mean ± SD)
107.6 ± 18.2
Racial or cultural groups (%)
Not aboriginal (%)
Born in a developed country (%)
Speaking English/French (%)
Highest degree of education (%)
No university degree or diploma
Trade certificate or diploma
No post-secondary degree, diploma
Hours at work (%)
Regular day, evening, or night time
Annual income ≤ 40000 (%)
Source of income (%)
Wages and salaries
Canada pension plan
Child tax benefit
Nutrition knowledge (%)
No previous nutrition counselling
Aware of Ontario school nutrition policy
Provided food for school
Allowed children to buy food at school- knowing the choices there are nutritious
Baseline measurement (Mean ± SD) for 6–11 year old children enrolled in the study
Boys 6–8 years old (n = 48)
Girls 6–8 years old (n = 36)
Boys 9–11 years old (n = 40)
Girls 9–11 years old (n = 44)
Total (N = 168)
91.2 ± 9.7
93.4 ± 10.2
122.0 ± 9.0
124.0 ± 9.5
107.6 ± 18.2
27.1 ± 5.4
28.2 ± 7.1
35.7 ± 8.6
39.4 ± 10.0
32.6 ± 9.4
125.4 ± 6.1
127.5 ± 6.8
139.6 ± 8.0
143.0 ± 8.9
133.8 ± 10.7
17.1 ± 2.5
17.1 ± 2.9
18.1 ± 3.3
19.0 ± 3.7
17.8 ± 3.2
0.5 ± 0.9
0.3 ± 1.0
0.2 ± 1.1
0.4 ± 1.0
0.4 ± 1.0
Weight status comparison using the WHO’s 2007 BMI-for-age tables vs. simplified overweight screening instrument
Weight status comparison
WHO’s 2007 BMI-for-age tables
Unhealthy n (%)
Healthy n (%)
Total n (%)
Unhealthy n (%)
59 (35.11) (a)
18 (10.71) (b)
Healthy n (%)
0 (0) (c)
91 (54.16) (d)
Total n (%)
Childhood obesity is a much bigger concern than its obvious impact on physical health. Obese children have a lower quality of life and impaired social functioning , and are at an increased risk of many conditions including: type 2 diabetes, hypertension, dyslipidemia, elevated cholesterol, coronary artery disease, obstructive sleep apnea, stroke, fatty liver disease, osteoarthritis, orthopedic problems and certain forms of cancer [3, 29]. The objective of this study was to identify the weight status of children from 6 to 11 years old in a dental setting and to evaluate the agreement between the WHO BMI-for-age tables and the simplified screening instrument tables, which were developed based on height and weight measurements and are derived from the 2007 WHO reference tables .
The BMI is the best method to identify obesity/overweight in children and depends on accurate weighing and measuring and making correct clinical judgments on the appropriateness of a child’s pattern of growth, for most clinical, screening and surveillance purposes . However, its under-utilization by healthcare providers, in particular in primary care setting, has been a point of concern [12–17, 31]. While it can be argued that the use of online BMI calculator and electronic health record and their integration to the clinical practice would enhance the use of BMI and the adherence to recommendations for screening and identification of childhood overweight and obesity ; some barriers such as navigation pathway needed to locate the required obesity-related form in the electronic health record, and minimal training of physicians, consistent with those encountered in other electronic health record interventions , remains to be the challenges associated with implementing interventions in a complex care system . Furthermore, poor information and communication technology, a limited to no access to internet, defective power resource, costs of equipment supply, and low level of technical skills can all play as barriers for health care providers in developing countries where the most burden of the disease is expected .
The simplified overweight screening instrument utilized in this study was previously published  and was developed following the methodology of Kaelber and Pickett in developing their simplified screening tool to identify children and adolescents needing further evaluation of blood pressure . This simplified tool consists of two gender-specific tables, through which, with the use of only the child's height and weight measurements without any additional computation, overweight screening can be performed.
There has been an increasing trends in visitation patterns of children to dentists , with a higher frequency of annual visits as compared to medical visits [12, 37, 38]. Children’s weight and height data are being routinely collected in dental offices who care for children, as part of a new patient medical history evaluation, and for calculation of safe dosages of local anesthesia for dental treatment under conscious or deep sedation. Therefore, dentists, specially pediatric dentists, can utilize dental visits to add additional screening and counseling that complements physicians’ efforts in addressing overweight or obesity and to refer those with unhealthy weight status to pediatricians or family physicians for further evaluations [14, 39]. In our setting, we found the application of this tool to be very feasible: with the minimal needed equipment, we were able to gather the weight and height from 168 children and use the tool to screen for overweight with no disruption to patient flow.
Our results showed an 89% overall agreement between the WHO BMI-for-age reference tables and the simplified screening instrument utilized in this research. In particular, the positive percent agreement of 100% means that none of the unhealthy weight individuals who were reported by WHO tables were screened as healthy weight status according to the screening tables. The only difference between the two techniques is that the simplified approach identified 18 participants as unhealthy weight status, while these participants were judged as healthy based on the WHO tables. This is in particular for the cases whose weight/height values put them on the borderline of being overweight. An example is illustrated in Fig. 1b. It can be argued that this difference is not only worrying, but also, could be a benefit for early identification of children with borderline unhealthy weight status due to the higher sensitivity of the simplified screening tables.
Although the study population was limited to a convenient university-based sample, for the purpose of the study objective, our study sample has an acceptable generalizability since 64.9% of our subjects, as compared to 65.5% of Canadian children from the Canadian Health Measurement Survey , had healthy weight status (P = 0.72). Hence, based on the generalizability and validity of this simplified screening instrument, it is expected that this screening tool would remove the burden of BMI calculation and would hopefully enhance overweight triage in primary care settings as well as school-based and community surveillance efforts . It has to be acknowledged that regardless, the healthcare professionals, specially those who care for children, would still need to have access to appropriate equipment to measure weight and height, introduce the idea of taking these measurements then undertake these measurements. At the end, health care professionals should promote active healthy living within each family unit, with focus on health rather than the actual weight numbers or physical appearance . An important aspect of the clinician’s responsibility that remains is related to communicating the overweight screening results to the parent in a supportive and culturally appropriate way rather than an accusatory way , in a manner that avoids judgment and the instillation of guilt in the parents .
This study has demonstrated the feasibility of weight, height and BMI measurement in a dental setting. It has further shown evidence that supports validity of a new simplified approach to assess children’s weight status without having to compute BMI. This simplified screening can enhance overweight triage in primary care settings as well as school-based and community surveillance efforts. Dentists who collaborate with other health care professionals have the potential to address childhood overweight/obesity and should determine height, weight for their patients at least annually and refer patients with unhealthy weight status to pediatricians, family physicians or registered dieticians.
Body mass index
World Health Organization.
The authors would like to gratefully acknowledge Junmin Yang for assistance with data analyses, Snezana Djuric for her clinic assistance, Adam Sgro, Santa Rabi, Sara Marandi, and Nima Laghapour-Lighvan for their help with the manuscript. This manuscript is based upon Master of Science thesis submitted by Anoushe Sekhavat to the University of Toronto in 2014 (https://tspace.library.utoronto.ca/bitstream/1807/68056/1/Sekhavat_Anoushe_201411_MSc_thesis.pdf). She expresses her special gratitude to Dr. Hashim Nainar, Faculty of Dentistry, University of Toronto as this work would have not been possible without his help.
This study was funded by Discipline of Pediatric Dentistry, Faculty of Dentistry, University of Toronto.
Availability of data and materials
More data related to this work is available from https://tspace.library.utoronto.ca/bitstream/1807/68056/1/Sekhavat_Anoushe_201411_MSc_thesis.pdf. De-identified raw data may be available upon request from the corresponding author.
AA, AS, and MJS conceptualized and designed the study. AS conducted the study. AA and AS performed the data analysis and interpretation. AA prepared the manuscript. AA and AS reviewed and revised the manuscript. All authors read and approved the final manuscript as submitted.
The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article.
Consent for publication
Ethics approval and consent to participate
The research protocol and its written informed consent were approved by the Research Ethics Board of the University of Toronto (Protocol No. 28052). Written consent to participate was given on behalf of the children (under the age of 16) by their parents/legal guardians.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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