Assessment of obesity among children aged 4’17 years using waist-to-height ratio and its correlation with blood pressure

Archana Reddy Damireddy; Sumanth Reddy Musali

doi:10.4103/mjhs.mjhs_55_22

ORIGINAL ARTICLE

Year : 2023 | Volume : 11 | Issue : 2 | Page : 154-159

Assessment of obesity among children aged 4’17 years using waist-to-height ratio and its correlation with blood pressure

Archana Reddy Damireddy¹, Sumanth Reddy Musali²
¹ Department of Pediatrics, SVS Medical College, Mahbubnagar, Telangana, India
² Department of General Medicine, SVS Medical College, Mahbubnagar, Telangana, India

Date of Submission	20-Jul-2022
Date of Decision	12-Aug-2022
Date of Acceptance	25-Sep-2022
Date of Web Publication	18-Apr-2023

Correspondence Address:
Sumanth Reddy Musali
Department of General Medicine, SVS Medical College, Mahbubnagar, Telangana
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjhs.mjhs_55_22

Abstract

Background: A tool to detect overweight and obesity among children should be simple, reliable, valid, and cost-effective. There is a need to monitor obesity among children in different populations. For this, there should be only one tool that is accepted worldwide or nationally which can be used to detect and compare the trends in different population settings.
Objective: To assess obesity among children aged 4–17 years using waist-to-height ratio and to study its correlation with blood pressure.
Materials and Methods: A hospital-based cross-sectional study was carried out among 261 children aged 4–17 years. Different variables such as age, sex, residence, parent's education and occupation, total family income per year, total family members, height, weight, waist circumference, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were considered.
Results: The mean age was 8.05 ± 2.75 years. The mean height was 122.71 ± 16.06 cm. The mean waist-to-height ratio was 0.45 ± 0.05. Males were more than females. Children from rural areas were more. The prevalence of obesity based on waist-to-height ratio was 19.2%. Waist-to-height ratio was significantly correlated with age, height, weight, body mass index (BMI), DBP, father education, mother education, and mother occupation. SBP was not correlated with waist-to-height ratio, but DBP was significantly correlated. As waist-to-height ratio increased by one unit, DBP increased by 0.157 mmHg. Age and weight were significantly associated with waist-to-height ratio.
Conclusion: The overall prevalence of obesity using waist-to-height ratio was 19.2%. Waist-to-height ratio was significantly correlated with age, height, weight, BMI, DBP, waist circumference, father education, mother education, and mother occupation. Age and body weight were significantly associated with waist-to-height ratio.

Keywords: Age, blood pressure, children, obesity, waist-to-height ratio

How to cite this article:
Damireddy AR, Musali SR. Assessment of obesity among children aged 4’17 years using waist-to-height ratio and its correlation with blood pressure. MRIMS J Health Sci 2023;11:154-9

How to cite this URL:
Damireddy AR, Musali SR. Assessment of obesity among children aged 4’17 years using waist-to-height ratio and its correlation with blood pressure. MRIMS J Health Sci [serial online] 2023 [cited 2023 Oct 4];11:154-9. Available from: http://www.mrimsjournal.com/text.asp?2023/11/2/154/374280

Introduction

Globally, there is an increasing trend of the obesity among children. Children who are obese are more likely to be obese in their adult life, leading to increased risk of morbidity and mortality associated with the obesity.^[1],[2] Slowly and steadily, obesity is becoming more and more common even in developing countries like India. It is likely to replace the problem of undernutrition in coming decades. India faces double burden of undernutrition and overnutrition in the form of obesity. Undernutrition in India is more common among those who live in rural and urban slum areas. Children from other places of India are more prone to overweight and obesity problem. These are linked to the increase in the income, changes in the lifestyle of the people, availability of food, etc.^[3]

Thus, early detection and appropriate intervention are need of the hour. The tool to detect overweight and obesity among children should be simple, reliable, valid, and cost-effective. There is also a need to monitor the obesity among children in different populations. For this, there should be only one tool that is accepted worldwide or nationally which can be used to detect and compare the trends in different population settings. There is no dearth of tools available. We have different available tools such as percentiles for body mass index (BMI), waist circumference, and waist-to-height ratio. These are all accepted and widely used. However, which one fits better for children is not so clear yet.^[4]

Percentiles for BMI are used in children for the purpose of epidemiological studies and clinical purpose. However, many suggest that BMI is not that sensitive for pediatric obesity as it is unable to indicate about the distribution of the fat in the body. Some have suggested to use the waist circumference as among children, the fat is deposited beneath the skin and intra-abdominally.^[5]

However, in the waist circumference, body height and weight are not taken into consideration as they are important. Therefore, waist-to-height ratio has been considered to overcome these limitations associated with the BMI and the waist circumference. It effectively predicts the metabolic risk and has been considered a better measure of distribution of the fat in the body. Compared to BMI, the advantage is that it can be used for all age groups and both the genders with single cutoff point. It is simply 0.5, which means that those having <0.5 are normal weight with minimum risk and those having 0.5 or more have moderate to increased risk for cardiovascular and metabolic diseases.^[6]

There is a lack of data which can tell about the relation of the waist-to-height ratio with overweight or obesity. It needs to be standardized. Till now, it has been established that those with waist-to-height ratio of more than or equal to 0.5 are considered overweight or obese irrespective of age and sex.^[7]

There is also a need to have more studies and data pertaining to waist-to-height ratio and its relation with blood pressure among children. Such studies are few. Hence, with this background, the present study was carried out to assess obesity among children aged 4–17 years using the waist-to-height ratio and to study its correlation with blood pressure.

Materials and Methods

A hospital-based cross-sectional study was carried out among 261 children aged 4–17 years from January 2022 to June 2022. The study was carried out at a tertiary care hospital among children who were attending the outpatient department of the hospital.

Children in the age group of 4–17 years and who were apparently healthy were included in the present study. Children with known chronic diseases were excluded.

The institutional ethics committee permission was obtained. Child assent was taken from parents of the children included in the study.

Sample size was calculated based on a previous study conducted by Kankaria et al.^[8] who found that the mean waist-to-height ratio in their study was 0.40 with a standard deviation of 0.05. Taking this into consideration, with 95% confidence level and absolute precision = 0.05, the sample size came out to be 246. Finally, we were able to include 261 eligible children.

Different variables such as age, sex, residence, parent's education and occupation, total family income per year, total family members, height, weight, waist circumference, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were considered in the present study.

Age was confirmed from the school records. The parents were requested to get any of the available school record to confirm the age. Parent's (mother and father) education was categorized as illiterate, primary, secondary, inter, and higher. Father occupation was categorized as unemployed, labor, service, and business. Mother occupation was categorized as homemaker, labor, service, and business. Total family income from all sources for that family was recorded in Indian Rupees.

Height, weight, and waist circumference were measured as per the standard guidelines laid down by the World Health Organization (WHO). Height was measured with the help of a stadiometer nearest to 0.5 cm. Weight was recorded with a digital standard weighing machine. The weighing machine was first standardized. At each recording, it was ensured to be zero. It was kept on a flat surface. The child was asked to remove shoes and any extra material in the pockets and to have minimal clothing. Weight was recorded to the nearest 0.1 kg. A flexible and inelastic measuring tape (2 m) was used to measure the waist circumference. It was taken at the level of umbilicus with abdomen exposed sufficiently in standing position and legs apart.^[9] Blood pressure was measured and classified as suggested by the WHO. Blood pressure was measured with the help of a standard mercury sphygmomanometer in the right arm in sitting position. It was kept at heart level and three readings at 5 min intervals were taken. The lowest reading was entered in the study questionnaire.^[10]

Waist-to-height ratio was calculated by dividing waist circumference in cm by height in cm. A cutoff of 0.5 cm was used to differentiate between normal weight and overweight obesity.^[11]

The data were collected using the Epicollect5 tool. This tool is available free and online. The study questionnaire was prepared and uploaded in this tool. The data were collected by trained nurses. Data quality and monitoring was done by the principal investigator. After data collection was complete, the Excel file was downloaded and exported to IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp. IBM Corp. Released 2015. Descriptive statistics was presented as number, proportion for categorical variables, and mean and standard deviation for continuous variables. Pearson's correlation was used to study correlation between different variables. Waist-to-height ratio was the outcome in the present study. Hence, those variables found to be correlated significantly with waist-to-height ratio were entered in the multiple linear regression model. Two-sided P < 0.05 was considered statistically significant.

Results

The mean age was 8.05 ± 2.75 years. The mean height was 122.71 ± 16.06 cm. The mean weight was 24.24 ± 10.33 kg. The mean BMI was 15.46 ± 2.93 kg/m². The mean waist circumference was 55.32 ± 8.9 cm. The mean SBP and DBP were 99.76 ± 11.35 mmHg and 67.02 ± 10.12 mmHg, respectively [Table 1].

Table 1: Distribution of study subjects as per anthropometry and clinical data

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Males were more than females. Children from rural areas were more compared to those from urban areas. The majority of parents (both mother and father) were educated to the level of higher than inter. Among fathers, majority (40.6%) were doing service, while among mothers, majority (58.6%) were homemakers. Majority (55.6%) had total family members up to four [Table 2].

Table 2: Distribution of study subjects as per sociodemographic characteristics

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The prevalence of obesity based on the waist-to-height ratio among children aged 4–17 years in this study was 19.2% [Table 3].

Table 3: Prevalence of obesity among children 4–17 years based on waist-to-height ratio

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Waist-to-height ratio was found to be significantly correlated with age, height, weight, BMI, DBP, father education, mother education, and mother occupation. There was a negative and significant correlation of age and height with waist-to-height ratio. Other variables from the above-mentioned list were positively and significantly correlated. As the parent's education and occupation (only mothers) moved toward the service and business, the waist-to-height ratio increased. As the age increased, the waist-to-height ratio tended to decrease by 0.15 cm with each increment of age by 1 year. SBP was not found to be correlated with waist-to-height ratio, but DBP was significantly correlated. As the waist-to-height ratio increased by one unit, the DBP increased by 0.157 mmHg [Table 4].

Table 4: Correlation of waist-to-height ratio with different variables

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Significantly correlated variables such as age, weight, father education, mother education, and mother occupation were entered in the multiple linear regression model. Other significantly correlated variables such as height and BMI were not entered in the model due to high levels of multicollinearity. SBP and DBP were also not entered as they are dependent on the waist-to-height ratio. The entered variables were able to explain 34.8% of variation in waist-to-height ratio. Among them, only age and weight were found to be significantly associated with waist-to-height ratio [Table 5].

Table 5: Correlates of waist-to-height ratio (results of multiple linear regression model)

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Age, waist circumference, and urban residence were significantly associated with SBP. As the age increased by 1 year, SBP increased by 0.780 mmHg. As the waist circumference increased by one cm, the SBP increased by 0.353. The children from urban areas had on an average SBP 5.085 mmHg more compared to their rural counterparts. BMI was not found to be associated with SBP even though it was significantly correlated with SBP [Table 6].

Table 6: Correlates of systolic blood pressure (results of multiple linear regression model)

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Only waist circumference was found to be significantly associated with DBP. As the waist circumference increased by one cm, DBP increased by 0.357 mmHg. Other variables such as BMI, residence, age, and waist-to-height ratio were not found to be associated with DBP [Table 7].

Table 7: Correlates of diastolic blood pressure (results of multiple linear regression model)

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Discussion

We found that the prevalence of obesity among children aged 4–17 years based on the waist-to-height ratio was 19.2%. Waist-to-height ratio was significantly correlated with age, height, weight, BMI, DBP, waist circumference, father education, mother education, and mother occupation. On multiple regression analysis, age and body weight were significantly associated with waist-to-height ratio, whereas for SBP, age, waist circumference, and urban residence were significantly associated, and for DBP, only waist circumference was significantly associated.

Maffeis et al.^[12] studied metabolic risk among children based on waist-to-height ratio. They found that children with high waist-to-height ratio had seven times the odds of metabolic risk compared to children with normal waist-to-height ratio. They stated that for waist circumference, population-based percentile charts are required for use, but the same is not required for waist-to-height ratio.

Campagnolo et al.^[13] assessed accuracy of waist-to-height ratio among 315 children aged 3–4 years compared to BMI and waist circumference in predicting cardiovascular risk. They observed that all these three parameters were equally good for predicting cardiovascular risk.

Kilinc et al.^[14] investigated the prevalence of obesity and to determine cutoff points of waist-to-height ratio among 2718 children aged 6–17 years. They found that obesity and central obesity were very well predicted by waist-to-height ratio. They concluded that for the diagnosis of central obesity and obesity, waist-to-height ratio can be used.

McCarthy and Ashwell^[15] studied 8135 children of age 5–16 years to see if waist-to-height ratio is influenced by age and sex. They found that as the age increased, waist-to-height ratio decreased significantly. The mean waist-to-height ratio was significantly more in boys. In the second survey, they found that the prevalence of obesity among boys was 17% and that among the girls was 11.7%, which was based on the waist-to-height ratio. This was lesser than that we found in the present study of 19.2%. They concluded that compared to BMI, waist-to-height ratio is a better predictor of morbidity among children.

Sarna et al.^[16] constructed age- and sex-specific reference growth charts for waist-to-height ratio (N = 68,261), BMI (N = 67,741), and waist circumference (N = 68,261). They observed that the waist circumference and BMI percentiles were lower in their study compared to other country data as well as data which reported previously from India. They found that the prevalence of obesity was 5.3% using waist-to-height ratio >0.5. This is very low compared to the present study finding of 19.2%.

Kuriyan et al.^[17] studied 9060 children aged 3–16 years from urban areas of India. They found that as the age increased, the mean waist circumference also increases in both the genders. They also observed that as the age increased, the waist-to-height ratio decreased. We also found in the present study that as the age increased by 1 year, the waist-to-height ratio decreased significantly by 0.016. They concluded that a cutoff point of waist-to-height ratio of 0.5 can be used.

Panjikkaran and Kumari^[18] found that the prevalence of overweight and obesity among children was 6.2% and 3.6%, respectively. However, in the present study, we found that the prevalence of obesity based on the waist-to-height ratio was 19.2%. The authors concluded that waist-to-height ratio and BMI can be used to establish obesity percentiles among school going children.

Mishra et al.^[19] examined whether waist-to-height ratio can be used to predict high blood pressure among 1913 children from urban schools of Bengaluru. They observed that the prevalence of high waist-to-height ratio was 13.9%, which is slightly lower compared to the present study of 19.2%. They also found that high BMI, waist circumference, and high waist-to-height ratio were associated with the high blood pressure. However, we found that waist-to-height ratio and BMI were not associated with high blood pressure; however, waist circumference was associated with high blood pressure. The authors concluded that as waist-to-height ratio is simple to measure and interpret, it is better to use to predict high blood pressure among children.

Kankaria et al.^[8] found from their study that the mean waist-to-height ratio was 0.40 ± 0.05, which is comparable to the present study finding of the mean waist-to-height ratio of 0.45 ± 0.05. They observed a U-shaped relation of age with waist-to-height ratio. We found an inverse relation of age with waist-to-height ratio. As the age increased by 1 year, the waist-to-height ratio decreased by 0.016. They noted that weight more than 30 kg was positively associated with waist-to-height ratio. We also found that after adjusting for age, parent education, and mother occupation, the weight was positively associated with waist-to-height ratio. The authors also reported a positive association with socioeconomic status, which we did not find.

Conclusion

The overall prevalence of obesity using waist-to-height ratio was 19.2%. Waist-to-height ratio was significantly correlated with age, height, weight, BMI, DBP, waist circumference, father education, mother education, and mother occupation. Age and body weight were significantly associated with waist-to-height ratio.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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