Validity of self-reported weight, height and resultant body mass index in Chinese adolescents and factors associated with errors in self-reports

Validity of self-reported weight and height among female young adults in the United Arab Emirates

Self-reported weight and height serve as important metrics in estimating overweight and obesity prevalence within epidemiological studies, primarily due to their cost and time efficiency. However, the accuracy and reliability of these self-reported measures remain controversial, with conflicting reports emerging from different regions. This study aims to compare self-reported weight and height with measured values among young female adults in the United Arab Emirates. A cross-sectional study of 131 female university students aged 17-27 reported their weight and height on a self-administered questionnaire and on the same day had their height and weight measured. Body Mass Index (BMI) values of both self-reported and measured weight and height were calculated and categorized according to the World Health Organization's cut-off points. Overall, 87% of students had a resultant self-reported BMI value within their actual BMI category. The mean differences between self-reported and measured weight and height in the present study were -0.92 kg and 0.38 cm, respectively. Results indicated strong agreement between self-reported and direct measurements, as demonstrated by weighted Kappa statistics (kappa = 0.87). Bland & Altman plots illustrated that the majority of values fell within the limits of agreement (2 SD), with no systemic bias detected. BMI calculated from self-reported data demonstrates high sensitivity and specificity. Linear regression analyses revealed that self-reported weight (r2 = 0.973; p<0.001), height (r2 = 0.902; p<0.001), and BMI (r2 = 0.964; p<0.001) accurately predicted measured weight, height, and BMI. The study's results highlight the ability of female university students in the UAE to accurately provide self-reports of their weight and height. This finding provides further support for the utilization of self-reported data on height and weight as a valid method for collecting anthropometric information.

Reliability of Self-Reported Height and Weight in Children: A School-Based Cross-Sectional Study and a Review

Since anthropometric measurements are not always feasible in large surveys, self-reported values are an alternative. Our objective was to assess the reliability of self-reported weight and height values compared to measured values in children with (1) a cross-sectional study in Switzerland and (2) a comprehensive review with a meta-analysis. We conducted a secondary analysis of data from a school-based study in Switzerland of 2616 children and a review of 63 published studies including 122,629 children. In the cross-sectional study, self-reported and measured values were highly correlated (weight: r = 0.96; height: r = 0.92; body mass index (BMI) r = 0.88), although self-reported values tended to underestimate measured values (weight: -1.4 kg; height: -0.9 cm; BMI: -0.4 kg/m²). Prevalence of underweight was overestimated and prevalence of overweight was underestimated using self-reported values. In the meta-analysis, high correlations were found between self-reported and measured values (weight: r = 0.94; height: r = 0.87; BMI: r = 0.88). Weight (-1.4 kg) and BMI (-0.7 kg/m²) were underestimated, and height was slightly overestimated (+0.1 cm) with self-reported values. Self-reported values tended to be more reliable in children above 11 years old. Self-reported weight and height in children can be a reliable alternative to measurements, but should be used with caution to estimate over- or underweight prevalence.

Linking EORTC QLQ-C-30 and PedsQL/PEDQOL physical functioning scores in patients with osteosarcoma

PURPOSE

The available questionnaires for quality-of-life (QoL) assessments are age-group specific, limiting comparability and impeding longitudinal analyses. The comparability of measurements, however, is a necessary condition for gaining scientific evidence. To overcome this problem, we assessed the viability of harmonising data from paediatric and adult patient-reported outcome (PRO) measures.

METHOD

To this end, we linked physical functioning scores from the Paediatric Quality of Life Inventory (PedsQL) and the Paediatric Quality of Life Questionnaire (PEDQOL) to the European Organisation for Research and Treatment of Cancer Core Questionnaire (EORTC QLQ-C30) for adults. Samples from the EURAMOS-1 QoL sub-study of 75 (PedsQL) and 112 (PEDQOL) adolescent osteosarcoma patients were concurrently administered both paediatric and adult questionnaires on 98 (PedsQL) and 156 (PEDQOL) occasions. We identified corresponding scores using the single-group equipercentile linking method.

RESULTS

Linked physical functioning scores showed sufficient concordance to the EORTC QLQ-C30: Lin's ρ = 0.74 (PedsQL) and Lin's ρ = 0.64 (PEDQOL).

CONCLUSION

Score linking provides clinicians and researchers with a common metric for assessing QoL with PRO measures across the entire lifespan of patients.

Adolescent's self-reported weight and its association with media impact on decision to lose weight and body thinness perception

This study investigated the accuracy of self-reported weight among Kuwaiti adolescents and the associations of self-reported weight and calculated BMI with the impact of media use on adolescent’s decision to lose weight and body thinness perception. A total of 706 Kuwaiti adolescents (363 females) 15–18 year-olds were randomly selected from schools. Weight and height were self-reported by the adolescents and measured by the researchers. A specifically designed questionnaire reported the impact of media use on adolescent’s decision to lose weight and body thinness perception. There were significant (p < 0.001) relationships between measured and reported weight (r = 0.947), height (r = 0.777), and calculated BMI (r = 0.623). Intraclass correlation coefficients (95% CI) between self-reported and measured weight and height were 0.973 (0.968–0.977) and 0.867 (0.839–0.891), respectively. The mean differences between self-reported and measured weight (1.26 kg) and BMI (0.478 kg/m²) were relatively small. Females under-reported their weight and the calculated BMI from estimated weight and height was underestimated by adolescents with overweight/obesity. The impact of media use on the adolescent’s perception of being thin relative to the accuracy of the calculated BMI was significant (p = 0.043–0.001). The age-adjusted odds ratio of the calculated (underestimated) BMI in adolescents without overweight/obesity was 0.437 (95% CI = 0.257–0.741; p = 0.002). It was concluded that the validity of self-reported weight was high. Adolescents with overweight/obesity were more likely to underestimate their weight and calculated BMI. Educating adolescents about proper lifestyles and weight loss through media appears warranted.

Nationwide Trends of Pediatric Obesity and BMI z-Score From 2017-2021 in China: Comparable Findings From Real-World Mobile- and Hospital-Based Data

INTRODUCTION

Lifestyle changes including COVID-19 lockdown cause weight gain and may change obesity trends; however, timely changes are largely unknown and monitoring measures are usually lack. This first large-scale study aimed to analyze the real-world national trends of obesity prevalence of Chinese children in the past five years, and the impact of COVID-19 pandemic on pediatric obesity development through both mobile- and hospital-based data.

METHODS

This study included children aged 3 to 19 years old all over China from January 2017 to April 2021. Hospital-measured and parent-reported cases from XIGAO database were analyzed. Body mass index (BMI) z-score calculation and obesity status evaluation were made according to Chinese standards. We evaluated obesity/overweight prevalence over the past five years and the changes of BMI z-score during COVID-19 lockdown.

RESULTS

A total of 656396 children from 31 provinces were involved, including 447481 hospital-measured cases and 208915 parent-reported cases. The obesity and overweight prevalence were 8.05% (95%CI 7.76%-8.39%) and 10.06% (95%CI 10.79%-11.55%), comparable to those of China National Nutrition Surveys during 2015-2019. Northern China had the highest obesity prevalence. Parent-reported data had higher obesity/overweight prevalence than hospital-measured data (18.3% [95%CI 17.7%-18.9%] vs. 21.7% [95%CI 20.7%-23.0%]). The trend of obesity prevalence remained stable with slight decrease, but COVID-19 lockdown caused a significant increase of 1.86% in 2020. Both mobile- and hospital-based data showed weight gain in the first half of 2020. High BMI z-score increase were found among primary and junior middle school children, and children in northeast area during lockdown.

CONCLUSION

Weight gain during COVID-19 among Chinese children had regional differences and mainly affect primary and junior middle school children, thus warrants targeted interventions. The mobile growth assessment based on parent-reported data was a feasible, efficient and timely way for obesity monitoring among Chinese children, especially during epidemic.

Potential Impacts of Body Image Perception in Female Equestrians

Female body image (BI) has been investigated in many sports yet, in female-dominated equestrianism, there is a paucity of BI research. This study aimed to identify self-perceptions of BI, rider perceptions of judge and coach bias, relationships between BI and self-consciousness and effect of breast size. A four-part, 27 question survey (GoogleForms) was completed by female equestrians (n = 493). The second smallest BI was considered ideal for equestrianism (χ² = 352.751, P < .001) regardless of age, own BI or level of riding commitment. There was a perception judges favor riders with smaller frames (χ² = 54.2111, P < .001) and an association between riders with a larger BI feeling self-conscious when riding (χ² = 87.514, P < .001). More respondents perceived the ideal equestrian BI to be smaller than theirs (Median = -1.5, W = 7777.00, P < .001) and an association between those dissatisfied with their BI and self-consciousness when riding was seen (χ² = 83.649, P < .001). Perception of the ideal equestrian frame is smaller than many riders' own BI, and a larger BI perception negatively impacts self-confidence, potentially hindering performance and participation. Female riders with a larger frame feel they are perceived negatively by judges and further study is indicated to investigate the extent of this potential bias on subjective judging in equestrian disciplines.

Validity of Self-reported Height, Weight, Body Mass Index, and Waist Circumference in Iranian Adults

Context:

The validity of self-reported anthropometric indices has been examined in previous studies in different populations.

Aims:

The aim of our study was to evaluate the validity of self-reported height, weight, body mass index (BMI), and waist circumference (WC) for the first time in middle-age staffs of Isfahan University of Medical Sciences.

Settings and Design:

In this cross-sectional study, a total of 171 men and women were selected from staffs of Isfahan University of Medical Sciences, Isfahan, Iran.

Methods and Materials:

Technician- and self-reported measurements of height, weight, and WC were collected from all participants. BMI was calculated by dividing weight in kg by height in meters squared. Overweight and obesity were defined as BMI ≥25-<29.9 and ≥30 kg/m², respectively. Abdominal obesity was defined as WC ≥94 and ≥80 cm in men and women, respectively.

Statistical Analysis:

Independent t-test, chi-square, Pearson and intraclass correlation coefficients (ICCs), as well as Kappa measurements, were used.

Results:

Fifty and 19 percentages of the study population were overweight and obese, respectively. Self-reported height (r = 0.83, P < 0.001, ICC =0.89, 95% confidence interval (CI): 0.85–0.92), weight (r = 0.95, P < 0.001, ICC = 0.979, 95% CI: 0.971–0.98), BMI (r = 0.70, P < 0.001, ICC = 0.81, 95% CI: 0.74–0.86), and WC (r = 0.60, P < 0.001, ICC = 0.71, 95% CI: 0.51–0.81) were highly correlated with actually measured ones. Approximately 80% and 65% of individuals who were defined as overweight and obese, respectively, based on actually measured data were correctly diagnosed as overweight and obese, respectively, based on self-reported data. The Kappa coefficients for different categories of weight situation and abdominal obesity were 0.59 and 0.32, respectively. Fifty-seven percent of participants who were diagnosed with abdominal obesity based on actually measured data were correctly diagnosed with abdominal obesity based on self-reported data. Also, approximately 48% and 69% of men and women, respectively, who were diagnosed with abdominal obesity based on actually measured data were correctly diagnosed with abdominal obesity based on self-reported ones.

Conclusions:

We found that self-reported data of anthropometric measures are reasonable in middle-age staff of Isfahan University of Medical Sciences. Nevertheless, self-reported data on WC should be cautiously relined on, in particular, among men.

Accuracy of self-reported height, weight and BMI in a multiethnic Asian population

Introduction: The study assessed whether self-reported height, weight and derived body mass index (BMI) can provide an accurate measure of anthropometric data in a multiethnic adult population in Singapore. Methods: Standardised anthropometric measurements were compared against the self-reported values from 5,132 adult residents in a cross-sectional, epidemiological survey. Discrepancies in self-reports from measurements were examined by comparing overall mean differences. Intraclass correlations, Cohen’s kappa and Bland-Altman plots with limits of agreement, and sub-analysis by sex and ethnicity were also explored. Results: Data were obtained from 5,132 respondents. The mean age of respondents was 43.9 years. Overall, the height was overestimated (0.2cm), while there was an underestimation of weight (0.8kg) and derived BMI (0.4kg/m2). Women had a larger discrepancy in height (0.35cm, 95% confidence interval [CI] 0.22 to 0.49), weight (-0.95kg, 95% CI -1.11 to -0.79) and BMI (-0.49kg/m2, 95% CI -0.57 to -0.41) compared with men. Height reporting bias was highest among Indians (0.28cm, 95% CI 0.12 to 0.44) compared with Chinese and Malays, while weight (-1.32kg, 95% CI -1.53 to -1.11) and derived BMI (-0.57kg/m2, 95% CI -0.67 to -0.47) showed higher degrees of underreporting among Malays compared with Chinese and Indians. Substantially high self-reported versus measured values were obtained for intraclass correlations (0.96–0.99, P<0.001) and kappa (0.74). For BMI categories, good to excellent kappa agreement was observed (0.68–0.81, P<0.0001). Conclusion: Self-reported anthropometric estimates can be used, particularly in large epidemiological studies. However, sufficient care is needed when evaluating data from Indians, Malays and women as there is likely an underestimation of obesity prevalence. Keywords: Body mass index, epidemiology, public health, self-report, validity

Accuracy of self-reported BMI using objective measurement in high school students

Self-reported measures for body mass index (BMI) are considered a limitation in research design, especially when they are a primary outcome. Studies have found some populations to be quite accurate when self-reporting BMI; however, there is mixed research on the accuracy of self-reported measurements in adolescents. The aim of this study is to examine the accuracy of self-reported BMI by comparing it with measured BMI in a sample of U.S. adolescents and to understand gender differences. This cross-sectional study collected self-reported height and weight measurements of students from five high schools in four states (Tennessee, South Dakota, Kansas and Florida). Trained researchers took height and weight of students for an objective measurement. BMI was calculated from both sources and categorized (underweight, normal, overweight and obese) using the Centers for Disease Control and Prevention's BMI-for-age percentiles. Participants (n 425; 51⋅0 % female) had a mean age of 16⋅3 years old, and the majority were White (47⋅5 %). Limits of agreement (LOA) analysis revealed that BMI and weight were underreported, and height was overreported in the overall sample, in females, and in males. LOA analysis was fair for BMI in all three groups. Overall agreement in BMI categorisation was considered substantial (Κ 0⋅71, P < 0⋅001). As BMI increased, more height and weight inaccuracies led to decreased accuracy in BMI categorisation, and the specificity of obese participants was low (50⋅0 %). This study's findings suggest that using self-reported values to categorize BMI is more accurate than using continuous BMI values when self-reported measures are used in health-related interventions.

Use and reporting of Bland-Altman analyses in studies of self-reported versus measured weight and height

BACKGROUND/OBJECTIVES

Bland-Altman methods for assessing the agreement between two measures are highly cited. However, these methods may often not be used to assess agreement, and when used, they are not always presented or interpreted correctly. Our objective was to evaluate the use and the quality of reporting of Bland-Altman analyses in studies that compare self-reported with measured weight and height.

METHODS

We evaluated the use of Bland-Altman methods in 394 published articles that compared self-reported and measured weight and height data for adolescents or adults. Six reporting criteria were developed: assessment of the normality of the distribution of differences, a complete and correctly labeled Bland-Altman plot displaying the mean difference and limits of agreement (LOA), numerical values and confidence intervals, standard errors, or standard deviations for mean difference, numerical values of LOA, confidence intervals for LOA, and prespecified criteria for acceptable LOA.

RESULTS

Only 72/394 (18%) studies comparing self-reported with measured weight and height or BMI used some form of Bland-Altman analyses. No study using Bland-Altman analyses satisfied more than four of the six criteria. Of the 72 studies, 64 gave mean differences along with confidence intervals or standard deviations, 55 provided complete Bland-Altman plots that were appropriately labeled and described, 37 provided numerical values for LOA, 4 reported that they examined the normality of the distribution of differences, 3 provided confidence intervals for LOA, and 3 had prespecified criteria for agreement.

CONCLUSIONS

Bland-Altman methods appear to be infrequently used in studies comparing measured with self-reported weight, height, or BMI, and key information is missing in many of those that do use Bland-Altman methods. Future directions would be defining acceptable LOA values and improving the reporting and application of Bland-Altman methods in studies of self-reported anthropometry.

Inequality, validity of self-reported height, and its implications for BMI estimates: An analysis of randomly selected primary sampling units' data

Any systematic errors in self-reported height, a measure commonly used in health research, may produce biased BMI estimates and reduce the effectiveness of public health interventions. To our knowledge, none of the studies evaluating the validity of self-reported height explore this issue in cross-national settings. This study analyses data on a sub-set of 750 individuals with information on self-reported and measured height from the Life in Transition Survey (LITS) conducted in 34 European and Central Asian countries in 2016. We make use of the unique design of LITS in which all respondents reported their height, but in one randomly selected primary sampling unit in each country the actual height was also measured, using a portable stadiometer. In addition to analysing individual-level characteristics, using a multiply imputed dataset for missing data and multilevel mixed-effects regressions, we test if macro-level factors are associated with respondents under- or over-reporting their height. We find that on the aggregate level self-reported and measured height estimates are not statistically different, but some socio-demographic groups such as women and those who live in rural areas are likely to overestimate their height. Adjusting for this bias would lead to the higher estimates of the proportion of individuals who are overweight and obese. The results from multilevel analysis also show that macro-level factors do not per se explain the likelihood of misreporting height, but rather some of the effects of individual characteristics are moderated by income inequality.

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Systematic errors in self-reported height may produce biased BMI estimates.

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On the aggregate level self-reported and measured height are indistinguishable.

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Women and those who live in rural areas are likely to overestimate their height.

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This bias can increase the estimated population BMI level by 2.1%.

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Some of the effects of individual variables are moderated by income inequality.

Biases in self-reported height and weight measurements and their effects on modeling health outcomes

Self-reported anthropometrics are often used as proxies for measured anthropometrics, but research has shown that heights and weights are often misreported. Using the Study on global AGEing and adult health, I analyze misreporting patterns of height, weight, and BMI in China, India, Russia, and South Africa. Adjustments of self-reported heights and weights using demographic, social, and anthropometric characteristics are evaluated and found to be useful in studying the distribution of anthropometrics within a population. Measured, self-reported, and adjusted BMI are then compared in logistic regression models on the reporting of health outcomes, as well as the resulting accuracy of individual prediction. When BMI is used as a continuous variable in models of health outcomes, measured, self-reported, and adjusted BMI produce similar coefficient estimates, and so self-reported data would be a natural choice because of its accessibility and convenience. In other applications, such as models using categorical BMI and individual prediction using either continuous or categorical BMI, self-reported data in lieu of measured data might not be accurate enough, but adjustments could serve as a potential compromise.

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There is heterogeneity in height and weight reporting patterns.

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Adjustments can be useful in studying population-level distributions.

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Variants of continuous BMI produce similar results in models of health outcomes.

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Variants of categorical BMI should not be used in lieu of measured data.

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Measured BMI is better for individual prediction of health outcomes.

Body mass index, body shape, and risk of nasopharyngeal carcinoma: A population-based case-control study in Southern China

Whether the association between body size or shape and nasopharyngeal carcinoma (NPC) risk exists or varies by age-specific body size indicators is unclear. In a population-based case-control study conducted in Southern China between 2010 and 2014, self-reported height, weight, and body shape at age 20 and 10 years before interview were collected from 2448 histopathologically confirmed NPC cases and 2534 population-based controls. Body mass index (BMI) was categorized according to the World Health Organization guidelines for Asian populations: underweight (<18.5 kg/m2 ), normal weight (18.5-22.9 kg/m2 ), overweight (23.0-27.4 kg/m2 ), and obese (≥27.5 kg/m2 ). Multivariate odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using logistic regression. Furthermore, restricted cubic spline analysis was employed to examine nonlinear effects of BMI and body shape as continuous covariates. Underweight vs normal weight at age 20 years was associated with a 22% decreased NPC risk (OR, 0.78; 95% CI, 0.67, 0.90), whereas obesity was not significantly associated with NPC risk. Associations with BMI 10 years before the interview were similar. Having the leanest body shape at age 20 years, compared with the mode was not significantly associated with NPC risk (OR, 0.85; 95% CI, 0.62, 1.16), but having a larger body shape was associated with an elevated risk (OR, 1.25; 95% CI, 1.03, 1.52). Increasing BMI revealed positive trends with NPC risk. Despite some indication of significant findings, evidence for a strong association between BMI or body shape and NPC risk is still limited.

How accurate is the prevalence of overweight and obesity in children and adolescents derived from self-reported data? A meta-analysis

OBJECTIVE

The aim of the current meta-analysis was to evaluate the accuracy of using BMI based on self-reported height and weight (BMIsr) to estimate the prevalence of overweight and obesity among children and adolescents.

DESIGN

A systematic literature search was conducted to select studies that compared the prevalence rates of overweight and obesity based on BMIsr and BMIm (BMI based on measured height and weight). A random-effect model was assumed to estimate summary prevalence rates and prevalence ratio (PR).

RESULTS

Thirty-seven studies were included. The aggregated prevalence of overweight and obesity based on BMIsr (0·190, 95 % CI 0·163, 0·221) was significantly lower than that based on BMIm (0·233, 95 % CI 0·203, 0·265). The pooled mean PR was 0·823 (95 % CI 0·775, 0·875). Moderator analyses showed that the underestimation was related to gender, age, weight status screened (overweight v. obesity) and weight status screening tool.

CONCLUSIONS

BMIsr may produce less biased results under some conditions than others. Future researchers using BMIsr may consider these findings and avoid the conditions that could lead to more severe underestimation of the prevalence of overweight and obesity among children and adolescents.

The validity of self-reported vs. measured body weight and height and the effect of self-perception

INTRODUCTION

The objective was to assess the validity of self-reported body weight and height and the possible influence of self-perception of body mass index (BMI) status on the actual BMI during the adolescent period.

MATERIAL AND METHODS

This cross sectional study was conducted on 3918 high school students. Accurate BMI perception occurred when the student's self-perception of their BMI status did not differ from their actual BMI based on measured height and weight. Agreement between the measured and self-reported body height and weight and BMI values was determined using the Bland-Altman metod. To determine the effects of "a good level of agreement", hierarchical logistic regression models were used.

RESULTS

Among male students who reported their BMI in the normal region, 2.8% were measured as overweight while 0.6% of them were measured as obese. For females in the same group, these percentages were 1.3% and 0.4% respectively. Among male students who perceived their BMI in the normal region, 8.5% were measured as overweight while 0.4% of them were measured as obese. For females these percentages were 25.6% and 1.8% respectively. According to logistic regression analysis, residence and accurate BMI perception were significantly associated with "good agreement" (p ≤ 0.001).

CONCLUSIONS

The results of this study demonstrated that in determining obesity and overweight statuses, non-accurate weight perception is a potential risk for students.

Self-Reported Height and Weight in Oceanian School-Going Adolescents and Factors Associated With Errors

We examined the accuracy of self-reported weight and height in New Caledonian school-going adolescents. Self-reported and measured height and weight data were collected from 665 adolescents of New Caledonia and were then compared. Multivariable logistic regressions identified the factors associated with inaccurate self-reports. Sensitivity and specificity of self-reported body mass index values to detect overweight or obesity were evaluated. Self-reported weight was significantly lower than measured weight (boys, -3.56 kg; girls, -3.13 kg). Similar results were found for height (boys, -2.51 cm; girls, -3.23 cm). Multiple regression analyses indicated that the difference between self-reported and measured height was significantly associated with ethnicity and pubertal status. Inaccurate self-reported weight was associated with socioeconomic status, place of residence, body-size perception and weight status. Screening accuracy of self-reported body mass index was low, particularly in the Melanesian subgroup. These findings should be considered when overweight is estimated in the Melanesian adolescent population at individual scale.

Validity of self-reported weight and height: a cross-sectional study among Malaysian adolescents

Background

Self-reported weight and height are commonly used in lieu of direct measurements of weight and height in large epidemiological surveys due to inevitable constraints such as budget and human resource. However, the validity of self-reported weight and height, particularly among adolescents, needs to be verified as misreporting could lead to misclassification of body mass index and therefore overestimation or underestimation of the burden of BMI-related diseases. The objective of this study was to determine the validity of self-reported weight and height among Malaysian secondary school children.

Methods

Both self-reported and directly measured weight and height of a subgroup of 663 apparently healthy schoolchildren from the Malaysian Adolescent Health Risk Behaviour (MyAHRB) survey 2013/2014 were analysed. Respondents were required to report their current body weight and height via a self-administrative questionnaire before they were measured by investigators. The validity of self-reported against directly measured weight and height was examined using intraclass correlation coefficient (ICC), the Bland-Altman plot and weighted Kappa statistics.

Results

There was very good intraclass correlation between self-reported and directly measured weight [r = 0.96, 95% confidence interval (CI): 0.93, 0.97] and height (r = 0.94, 95% CI: 0.90, 0.96). In addition the Bland-Altman plots indicated that the mean difference between self-reported and direct measurement was relatively small. The mean difference (self-reported minus direct measurements) was, for boys: weight, −2.1 kg; height, −1.6 cm; BMI, −0.44 kg/m² and girls: weight, −1.2 kg; height, −0.9 cm; BMI, −0.3 kg/m². However, 95% limits of agreement were wide which indicated substantial discrepancies between self-reported and direct measurements method at the individual level. Nonetheless, the weighted Kappa statistics demonstrated a substantial agreement between BMI status categorised based on self-reported weight and height and the direct measurements (kappa = 0.76, 95% CI: 0.67, 0.84).

Conclusion

Our results show that the self-reported weight and height were consistent with direct measurements and therefore can be used in assessing the nutritional status of Malaysian school children from the age of 13 to 17 years old in epidemiological studies and for surveillance purposes when direct measurements are not feasible, but not for assessing nutritional status at the individual level.

Accuracy of using self-reported data to screen children and adolescents for overweight and obesity status: A diagnostic meta-analysis

OBJECTIVE

To estimate the accuracy of using the self-reported body mass index (BMIsr) for screening children and adolescents for overweight and obesity status by quantitatively synthesizing individual studies in the research literature.

METHOD

Three databases, namely PubMed, Web of Science, and EBSCOhost were searched up to September 2016. Studies were included that collected both the self-reported data (BMIsr) and direct measurement data (i.e., BMI based on measured height and weight, BMIm) to screen children and adolescents for overweight and obesity status, and provided sufficient data on sensitivity and specificity. Sensitivity, specificity, likelihood ratios, and diagnostic odds ratios from each of the included studies were pooled by using a random-effects meta-analytic model, and summary receiver operating characteristic curve (ROC) was also constructed.

RESULTS

Twenty-three studies were identified. For screening children and adolescents with overweight and obesity, the use of BMIsr presented a pooled sensitivity of 0.76 (95% CI, 0.76-0.77), a pooled specificity of 0.96 (95% CI, 0.96-0.97) and a pooled DOR of 92.4 (95% CI: 74.3-114.8). Moderator analyses showed that the sample regions (America vs. Europe vs. Asia), weight status screening references (IOTF vs. CDC vs. Nation-specific standard) and weight status screened (overweight vs. obesity) had contributed to the inconsistent findings concerning the screening accuracy across the studies.

CONCLUSIONS

Based on the results of current meta-analysis, the use of BMIsr has good overall performance with moderate sensitivity and high specificity, and it is a viable alternative when direct measurement of BMI is not available.

Investigating the accuracy of parentally reported weights and lengths at 12 months of age as compared to measured weights and lengths in a longitudinal childhood genome study

BACKGROUND

Childhood obesity studies rely on parentally reported anthropometrics. However, the accuracy of such data has not been evaluated for 12-month-old children. Moreover, methods to improve the accuracy of reported data have not been assessed in prior studies.

METHODS

A total of 185 children enrolled in a northern Virginia childhood longitudinal cohort genomic study had parentally completed surveys at 12 months. Measured weights and lengths were recorded for the same children from their 12-month paediatrician visit. Weight for length percentiles were calculated using World Health Organization gender-specific growth charts. The agreement between reported and measured values was examined using Pearson's correlation, paired t-test and κ statistics. The interquartile outlier rule was used to detect and remove outliers.

RESULTS

Parentally reported weight was strongly associated with measured weight at 12 months (r=0.90). There was only a moderate correlation between parentally reported and measured lengths (r=0.52) and calculated weight for length percentiles (r=0.65). After removing outliers from parentally reported data, there was an increase in correlation between parentally reported and measured data for weight (r=0.93), length (r=0.69) and weight for length percentiles (r=0.76). Outliers removed compared to all children included were more likely to have maternal education less than a bachelor's degree (p=0.007).

CONCLUSIONS

After removal of outliers from reported data, there is a strong correlation between calculated reported and measured weight for length percentiles suggesting that this may be an effective method to increase accuracy when conducting large-scale obesity studies in young children where study costs benefit from using parentally reported data.

Social factors, weight perception, and weight control practices among adolescents in Mexico

We evaluated the association of social factors and weight control practices in adolescents, and the mediation of this association by weight perception, in a national survey of students in Mexico ( n = 28,266). We employed multinomial and Poisson regression models and Sobel's test to assess mediation. Students whose mothers had a higher level of education were more likely to perceive themselves as overweight and also to engage in weight control practices. After adjusting for body weight perception, the effect of maternal education on weight control practices remained significant. Mediation tests were significant for boys and non-significant for girls.

Validity of Self-Reports of Height and Weight among the General Adult Population in Japan: Findings from National Household Surveys, 1986

Background/Objectives

Growing evidence indicates that self-reported height and weight are biased, but little is known about systematic errors in the general adult population in Japan. This study takes advantage of the unique opportunity to examine this issue provided by the 1986 National Nutrition Survey.

Subjects/Methods

Individual-level data on a nationally representative sample aged 20–89 years from the National Nutrition Survey (November 1986) were merged with Comprehensive Survey of Living Conditions (September 1986) data to obtain a dataset containing both self-reported and measured data on height and weight for each person (n = 10,469). Discrepancies between self-reported and measured means of height, weight, and body mass index (BMI) were tested across measured BMI categories (<18.5, 18.5–24.9, 25.0–27.4, 27.5–29.9, and ≥30.0 kg/m²), age groups (20–44, 45–64, and 65–89 years), and sexes. Reporting bias in mean BMI was decomposed into the contributions of misreporting height and weight. The sensitivity and specificity of self-reported BMI categories were estimated.

Results

Mean self-reported BMI was substantially underestimated in older women (P<0.001; Cohen’s d, -0.4), and the major contributor to the bias was their over-reported height. Mean self-reported BMI was also considerably underestimated in both men and women who were overweight and obese (P<0.001; Cohen’s d, -1.0 to -0.6), due mainly to their underreported weight. In contrast, mean self-reported BMI was considerably overestimated in underweight men (P<0.001; Cohen’s d, 0.5), due largely to their over-reported weight. The sensitivity of self-reported BMI categories was particularly low for individuals who had a measured BMI of 27.5–29.9 kg/m² (40.9% for men and 26.8% for women).

Conclusions

Self-reported anthropometric data were not sufficiently accurate to assert the validity of their use in epidemiological studies on the general adult population in Japan in the late 1980s.

Decomposing the effect of height on income in China: The role of market and political channels

It is well known that height is positively associated with earnings. Based on individual level data, this paper investigates the channels through which height influences income in China. Our first key finding is that for males (females) a 1 centimeter (cm) increase in height leads to a 0.5% (0.02%) increase in the probability that he (she) becomes a Communist Party member. Further, the hourly wage of Communist Party members is approximately 11% higher than non-members for males, while no difference in the hourly wage between Party members and non-members is observed for females. Therefore, a 1cm increase in height leads to approximately a 0.06% increase in the hourly wage, which is observed only for males. We label this the height premium in earnings through the political channel. Second, controlling for the political channel of the height premium, a 1cm increase in height leads to a 1.18% (1.04%) increase in the hourly wage for males (females). We label this the height premium through the market channel. Together, these results suggest that the height premium in earnings through the market channel is much larger than that through the political channel.

Does BMI generated by self-reported height and weight measure up in older adults from middle-income countries? Results from the study on global AGEing and adult health (SAGE)

BACKGROUND

Self-reported (SR) body mass index (BMI) values are often used to determine obesity prevalence. However, individuals frequently overestimate their height and underestimate their weight, resulting in artificially lower obesity prevalence rates. These patterns are especially apparent among older adults and overweight individuals. The present cross-sectional study uses nationally representative datasets from five countries to assess the accuracy of SR BMI values in diverse settings.

METHODS

Samples of older adults (≥50 years old) and comparative samples of younger adults (18-49 years old) were drawn from five middle-income countries (China, India, Mexico, Russian Federation, and South Africa) in the World Health Organization's Study on global AGEing and adult health (SAGE). Participant-reported and researcher-obtained height and weight measures were used to calculate SR and measured BMI, respectively. Paired t-tests assessed differences between SR and measured BMI values by country. Linear regressions examined the contribution of measured weight and age to differences between SR and measured BMI.

RESULTS

Significant differences between SR and measured BMI values were observed (p < 0.05), but the direction of these discrepancies varied by country, age, and sex. Measured weight significantly contributed to differences between SR and measured BMI in all countries (p < 0.01). Age did not contribute significantly to variation in BMI discrepancy, except in China (p < 0.001).

CONCLUSIONS

These results suggest that SR BMI may not accurately reflect measured BMI in middle-income countries, but the direction of this discrepancy varies by country. This has considerable implications for obesity-related disease estimates reliant on SR data.

Validity of self-reported height and weight for estimating prevalence of overweight among Estonian adolescents: the Health Behaviour in School-aged Children study

Background

Low to moderate agreement between self-reported and directly measured anthropometry is shown in studies for adults and children. However, this issue needs further evaluation during puberty, a period marked by several transitions. We examined the correspondence of BMI status based on self-reported versus measured anthropometric data among Estonian adolescents with a specific focus on gender and age differences.

Methods

Self-reported height and weight were determined in a national representative sample of Estonian schoolchildren collected within the framework of the HBSC (health behaviour of school-aged children) survey. Self-reported and directly measured height and weight were collected from 3379 students (1071 aged 11, 1133 aged 13 and 1175 aged 15 years). The standardized HBSC questionnaire was used for collecting self-reported data; direct anthropometric measures were taken after the HBSC questionnaires were completed. The accuracy of the self-reported values by age and gender groups were determined by comparing mean differences, Bland–Altman plots with limits of agreement, Kappa statistics, and by estimation of the sensitivity and positive predictive value for detecting overweight.

Results

Mean self-reported weight, height and body mass index (BMI) values were significantly lower than corresponding values obtained using direct measurements. Mean differences between self-reported and directly measured weight, height and BMI were largest among 11-year-olds and smallest among students aged 15 years. Underestimation of overweight prevalence (includes obese) showed a graded trend which decreased in older age groups; the difference was greater among girls than boys in all age groups. The mean underestimation of overweight prevalence based on self-reported anthropometry was 3.6 percentage points. The positive predictive value was 72.3 % for boys and 63.4 % for girls.

Conclusion

A distinct age-related pattern in underestimation of weight, height and prevalence of overweight was found; the bias decreased with increasing age. The mean underestimation of overweight prevalence based on self-reports was small, 3.6 %. Self-reported height and weight remain the method of choice in large surveys for practical and logistical reasons.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1587-9) contains supplementary material, which is available to authorized users.

The Causal Effects of Rural-to-Urban Migration on Children's Wellbeing in China

China's rural-to-urban migration has affected 12.6 million school-age rural children who have migrated with their parents and another 22 million who have been left behind by their migrant parents. Not enough is known, either theoretically or empirically, about the causal impact of migration on the wellbeing of this large number of Chinese children affected by migration. Propensity score matching methods are applied to estimate the effects of migration in children 10-15 years old from a 2010 national survey (N = 2,417). Children's migration has significant positive effects on their objective wellbeing but no negative effects on their subjective wellbeing. There is little difference between the left-behind and non-migrant children across multiple life domains. The Rosenbaum bounds tests indicate that the causal effects of child migration are sensitive to hidden bias for certain outcomes, but not for others.

Systematic review to identify and appraise outcome measures used to evaluate childhood obesity treatment interventions (CoOR): evidence of purpose, application, validity, reliability and sensitivity

BACKGROUND

Lack of uniformity in outcome measures used in evaluations of childhood obesity treatment interventions can impede the ability to assess effectiveness and limits comparisons across trials.

OBJECTIVE

To identify and appraise outcome measures to produce a framework of recommended measures for use in evaluations of childhood obesity treatment interventions.

DATA SOURCES

Eleven electronic databases were searched between August and December 2011, including MEDLINE; MEDLINE In-Process and Other Non-Indexed Citations; EMBASE; PsycINFO; Health Management Information Consortium (HMIC); Allied and Complementary Medicine Database (AMED); Global Health, Maternity and Infant Care (all Ovid); Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCOhost); Science Citation Index (SCI) [Web of Science (WoS)]; and The Cochrane Library (Wiley) - from the date of inception, with no language restrictions. This was supported by review of relevant grey literature and trial databases.

REVIEW METHODS

Two searches were conducted to identify (1) outcome measures and corresponding citations used in published childhood obesity treatment evaluations and (2) manuscripts describing the development and/or evaluation of the outcome measures used in the childhood intervention obesity evaluations. Search 1 search strategy (review of trials) was modelled on elements of a review by Luttikhuis et al. (Oude Luttikhuis H, Baur L, Jansen H, Shrewsbury VA, O'Malley C, Stolk RP, et al. Interventions for treating obesity in children. Cochrane Database Syst Rev 2009;1:CD001872). Search 2 strategy (methodology papers) was built on Terwee et al.'s search filter (Terwee CB, Jansma EP, Riphagen II, de Vet HCW. Development of a methodological PubMed search filter for finding studies on measurement properties of measurement instruments. Qual Life Res 2009;18:1115-23). Eligible papers were appraised for quality initially by the internal project team. This was followed by an external appraisal by expert collaborators in order to agree which outcome measures should be recommended for the Childhood obesity Outcomes Review (CoOR) outcome measures framework.

RESULTS

Three hundred and seventy-nine manuscripts describing 180 outcome measures met eligibility criteria. Appraisal of these resulted in the recommendation of 36 measures for the CoOR outcome measures framework. Recommended primary outcome measures were body mass index (BMI) and dual-energy X-ray absorptiometry (DXA). Experts did not advocate any self-reported measures where objective measurement was possible (e.g. physical activity). Physiological outcomes hold potential to be primary outcomes, as they are indicators of cardiovascular health, but without evidence of what constitutes a minimally importance difference they have remained as secondary outcomes (although the corresponding lack of evidence for BMI and DXA is acknowledged). No preference-based quality-of-life measures were identified that would enable economic evaluation via calculation of quality-adjusted life-years. Few measures reported evaluating responsiveness.

LIMITATIONS

Proposed recommended measures are fit for use as outcome measures within studies that evaluate childhood obesity treatment evaluations specifically. These may or may not be suitable for other study designs, and some excluded measures may be more suitable in other study designs.

CONCLUSIONS

The CoOR outcome measures framework provides clear guidance of recommended primary and secondary outcome measures. This will enhance comparability between treatment evaluations and ensure that appropriate measures are being used. Where possible, future work should focus on modification and evaluation of existing measures rather than development of tools de nova. In addition, it is recommended that a similar outcome measures framework is produced to support evaluation of adult obesity programmes.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Web-based self-reported height, weight, and body mass index among Swedish adolescents: a validation study

Background

Web-collected height and weight are increasingly used in epidemiological studies; however, the validity has rarely been evaluated.

Objective

The aim of the study was to validate self-reported height, weight, and corresponding body mass index (BMI) among Swedish adolescents aged approximately 16 years. A secondary aim was to investigate possible prediction factors for validity of self-reported BMI.

Methods

The study included 1698 adolescents from the population-based cohort BAMSE. Height and weight were collected through a Web-based questionnaire and subsequently measured using standard procedures. Differences between reported and measured height, weight, and corresponding BMI were compared by t tests and agreement was evaluated by Pearson correlation and Bland-Altman plots. Multivariable linear regression analysis was used to investigate whether lifestyle and demographic factors predicted validity of self-reported BMI.

Results

On average, weight was underestimated by 1.1 kg and height was overestimated by 0.5 cm, leading to an underestimation of BMI by 0.5 kg/m2. Correlation coefficients were .98 for height, .97 for weight, and .94 for BMI, and highly significant. Females underestimated weight to a higher extent than males and overweight and obese participants underestimated weight to a higher extent than normal-weight participants, which resulted in higher underestimation of BMI. Underweight participants, on the contrary, overestimated weight and correspondingly BMI. Overall, a high proportion of participants were classified into the correct BMI category; however, among overweight and obese participants, only 60.2% (139/231) and 46% (20/44) were correctly classified, respectively. In the multivariable prediction model, only gender and BMI status significantly predicted discrepancy between reported and measured BMI.

Conclusions

Web-collected BMI may be used as a valid, quick, and cost-effective alternative to measured BMI among Swedish adolescents. The accuracy of self-reported BMI declines with increasing BMI and self-reported BMI should not be used to estimate the prevalence of overweight or obesity.

The role of answering behaviours on weight misreporting

BACKGROUND

Biases in self-reported weight are very common among young adults and adults. Although social norms are the most commonly accepted explanation for these misreports, corresponding evidence is scarce and conflict-ridden. An alternative explanation for biases in weight self-reports comes from answering behaviours; non-random rounding, formally an answering behaviour, has been found to play a significant role in several studies of weight misreporting. However, the presumably rich role of answering behaviours has seldom been explored. This study brings a second answering behaviour into the analysis: inconsistency.

METHODS

An inconsistency index was computed as an individual-level score from several questions across waves in the National Health and Nutrition Examination Survey. By regression analysis (N=3480 men and 1856 women) the simultaneous role of inconsistency and of non-random rounding on weight misreporting was explored.

RESULTS

Inconsistency was found to be associated with higher self-reported weights. Inconsistent individuals provided significantly different misreports, with women under-reporting 0.23[kg] (0.01-0.45) less and men over-reporting 0.42[kg] (0.02-0.82) more than their consistent counterparts. Inconsistency was found to play a simultaneous and substantially larger role than non-random rounding. This result was clearer among men than it was among women.

DISCUSSION

Although social norms are usually thought to be the central explanation of weight-biased misreports, there are other factors, such as answering behaviours, that might play a more influential role.

Factor structure and psychometric properties of the Body Appreciation Scale among adults in Hong Kong

Previous research has suggested that the factor structure of Body Appreciation Scale (BAS), a widely-used measure of positive body image, may not be cross-culturally equivalent. Here, we used confirmatory factor analysis to evaluate the conceptual equivalence of a Chinese (Cantonese) translation of the BAS among women (n=1319) and men (n=1084) in Hong Kong. Results showed that neither the one-dimensional nor proposed two-dimensional factor structures had adequate fit. Instead, a modified two-dimensional structure, which retained 9 of the 13 BAS items in two factors, had the best fit. However, only one of these factors, reflective of General Body Appreciation, had adequate internal consistency. This factor also had good patterns of construct validity, as indicated through significant correlations with participant body mass index, self-esteem, and (among women) actual-ideal weight discrepancy. The present results suggest that there may be cultural differences in the concept and experience of body appreciation.

The prevalence of underweight, overweight, obesity and associated risk factors among school-going adolescents in seven African countries

Background

The burden caused by the coexistence of obesity and underweight in Low and Middle Income Countries is a challenge to public health. While prevalence of underweight among youth has been well documented in these countries, overweight, obesity and their associated risk factors are not well understood unlike in high income countries.

Methods

Cross-sectional data from the Global School-based Student Health Survey (GSHS) conducted in seven African countries were used for this study. The survey used a clustered design to obtain a representative sample (n = 23496) from randomly selected schools. 53.6% of the sample was male, and participants ranged in age from 11-17 years old. Body Mass Index (BMI) was calculated using age and sex adjusted self-reported heights and weights. Classification of weight status was based on the 2007 World Health Organization growth charts (BMI-for-age and sex). Multivariable Logistic Regression reporting Odds Ratios was used to assess potential risk factors on BMI, adjusting for age, sex, and country. Statistical analyses were performed with Stata with an alpha of 0.05 and reporting 95% confidence intervals.

Results

Unadjusted rates of being underweight varied from 12.6% (Egypt) to 31.9% (Djibouti), while being overweight ranged from 8.7% (Ghana) to 31.4% (Egypt). Obesity rates ranged from 0.6% (Benin) to 9.3% (Egypt). Females had a higher overweight prevalence for every age group in five of the countries, exceptions being Egypt and Malawi. Overall, being overweight was more prevalent among younger (≤12) adolescents and decreased with age. Males had a higher prevalence of being underweight than females for every country. There was a tendency for the prevalence of being underweight to increase starting in the early teens and decrease between ages 15 and 16. Most of the potential risk factors captured by the GSHS were not significantly associated with weight status.

Conclusions

The prevalence of both overweight and underweight was relatively high, demonstrating the existence of the double burden of malnutrition among adolescents in developing countries. Several factors were not associated with weight status suggesting the need to explore other potential risk factors for overweight and underweight, including genetic factors and socioeconomic status.

Discrepant body mass index: behaviors associated with height and weight misreporting among US adolescents from the National Youth Physical Activity and Nutrition Study

BACKGROUND

The accuracy and reliability of self-reported height and weight among adolescents in the process of calculating BMI is usually subject to bias. The aim of this study was to determine whether over- and under-reporting of self-reported height and weight existed among US high school students by weight category; if so, to examine anthropometric, behavioral, and demographic factors associated with over- and under-reporting.

METHODS

Data were retrieved from the National Youth Physical Activity and Nutrition Study, 2010, a nationally representative sample (7160 students, grades 9-12). Analysis of variance was performed to determine any significant difference between weight categories in misreporting. Discriminant function analysis and sequential logistic regression were executed to detect behavioral and demographic predictors of reporting accuracy, respectively.

RESULTS

The mean over-reporting of height and under-reporting of weight were 1.1 cm and 1.020 kg, respectively, which underestimated BMI and BMI percentile by 0.671 and 2.734, respectively. Use of self-reported height and weight for BMI calculation overestimated prevalence of healthy weight by 3.8% and underestimated prevalence of obesity by 4.1%. Underweight students under-reported height and over-reported weight, whereas overweight and obese students over-reported height and under-reported weight. Reporting accuracy of females was significantly higher. Weight loss behaviors, both healthy and unhealthy, were associated with BMI underestimation, whereas fast foods and screen time were associated with overestimation.

CONCLUSION

Whenever possible, measuring height and weight is essential. However, because many studies must rely on self-reported values alone, additional research should examine the relationships between misreport of anthropometric data and lifestyle features in diverse adolescent samples to better interpret self-reported anthropometric data.

Validity of self-measured waist and hip circumferences: results from a community study in Malaysia

Background

Measures of central adiposity are better predictors of adverse health events than BMI. Nonetheless, BMI is more widely used in health research. One reason for this may be the limited research supporting the self-measurement of waist and hip circumference. The lack of validity studies is particularly acute in Asia. The main objective was to establish the validity of self-measurement of waist and hip circumference in a community setting and the correlation of those measures with BMI, blood pressure, and blood glucose levels.

Methods

A community based, cross-sectional survey. A “healthy living expo” at a shopping mall in a rural town on peninsular Malaysia One hundred and thirty six (136) individuals volunteered to participate in the study, 125 of whom met the inclusion criteria. The ethnic distribution of the participants was 80% Chinese, 17% Malay and 3% Indian. Most participants were female (60%), with participants’ ages ranging from 18 to 78 years (mean, 47.2). Self and assisted measurements of waist and hip were taken. Blood pressure, non-fasting blood glucose, height, and weight were also measured. Bland Altman plots and Lin’s concordance coefficient were used to measure agreement between self and assisted measures. Pearson’s correlation was used to examine the association of self and assisted measures with blood pressure, blood glucose, and BMI.

Results

There was a downwards bias in self measured waist (-0.81 cm) and hip (-1 cm) circumferences compared with assisted measures. The concordance for the self and assisted measures of waist, hip and the ratio of the two were, respectively, .96, .93 , and .84. The correlation between measures of central adiposity and BMI, blood pressure and blood glucose were similar for self and assisted measures.

Conclusion

The results provide additional support for the use of self-measurement of waist and hip circumference studies of central adiposity, but is limited by the specificity of the setting.

Validity of self-reported weight and stature in adolescents from Cuiabá, Central-Western Brazil

OBJECTIVE: This study assessed the agreement between self-reported and measured weight and stature in adolescents. METHODS: Ninety-seven students from public and private high schools of Cuiabá, in the state of Mato Grosso, Brazil (14 to 19 years old), were examined to assess the validity of self-reported weight and stature. The adolescents reported their weight and stature, which were subsequently measured by standard procedures. The body mass index was calculated from both self-reported and measured data. Weight status was classified according to body mass index Z-score and World Health Organization criteria. The differences between the self-reported and measured means were tested by the Student's paired t-test. Weighted Kappa's coefficient of agreement was used to assess the variations in weight status categorization using informed and measured data. Agreement between measurements was assessed by the Bland-Altman method and intraclass correlation coefficient. RESULTS: The means of self-reported and measured weights (p=0.30), statures (p=0.76) and body mass index (p=0.47) were not significantly different. There was high agreement between self-reported and measured measurements according to intraclass correlation coefficient (weight: r=0.99; stature: r=0.96; body mass index: r=0.97) and the mean agreements estimated by the Bland-Altman method were 99% for weight and 100% for stature. CONCLUSION: Given the excellent agreement with measured data, self-reported weight and stature are considered valid to be used in epidemiological studies on adolescents of Cuiabá, Mato Grosso, Brazil.

[Self-assessment of BMI data : verification of the practicability of a correction formula on a sample of 11- to 13-year-old girls]

The decision to measure or to ask about data concerning height and weight in order to calculate body mass index (BMI) has an influence on the economy and validity of the measurements. Although self-reported information is less expensive, this information may possibly have a bias on the determined prevalences of different weight groups. Using representative data from the KiGGS study with a comparison of directly measured and self-reported BMI data, Kurth and Ellert (2010) developed two correction formulas for prevalences resulting from self-reported information. The aim of the study was to examine the practicability of the proposed correction formulas on our own data concerning self-reported BMI data of 11- to 13-year-old girls (n=1,271) and to assess the plausibility of the corrected measurements. As a result, the prevalences of our own data changed in the expected direction both for underweight and for overweight. Both formulas were found to be practicable, the consideration of the subjective weight status (formula 2) resulted in a greater change in prevalences compared to the first correction formula.

Validity and predictors of BMI derived from self-reported height and weight among 11- to 17-year-old German adolescents from the KiGGS study

Background

For practical and financial reasons, self-reported instead of measured height and weight are often used. The aim of this study is to evaluate the validity of self-reports and to identify potential predictors of the validity of body mass index (BMI) derived from self-reported height and weight.

Findings

Self-reported and measured data were collected from a sub-sample (3,468 adolescents aged 11-17) from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). BMI was calculated from both reported and measured values, and these were compared in descriptive analyses. Linear regression models with BMI difference (self-reported minus measured) and logistic regression models with weight status misclassifications as dependent variables were calculated.

Height was overestimated by 14- to 17-year-olds. Overall, boys and girls under-reported their weight. On average, BMI values calculated from self-reports were lower than those calculated from measured values. This underestimation of BMI led to a bias in the prevalence rates of under- and overweight which was stronger in girls than in boys. Based on self-reports, the prevalence was 9.7% for underweight and 15.1% for overweight. However, according to measured data the corresponding rates were 7.5% and 17.7%, respectively. Linear regression for BMI difference showed significant differences according to measured weight status: BMI was overestimated by underweight adolescents and underestimated by overweight adolescents. When weight status was excluded from the model, body perception was statistically significant: Adolescents who regarded themselves as 'too fat' underestimated their BMI to a greater extent. Symptoms of a potential eating disorder, sexual maturation, socio-economic status (SES), school type, migration background and parental overweight showed no association with the BMI difference, but parental overweight was a consistent predictor of the misclassification of weight status defined by self-reports.

Conclusions

The present findings demonstrate that the observed discrepancy between self-reported and measured height and weight leads to inaccurate estimates of the prevalence of under- and overweight when based on self-reports. The collection of body perception data and parents' height and weight is therefore recommended in addition to self-reports. Use of a correction formula seems reasonable in order to correct for differences between self-reported and measured data.

Need for weight management in Switzerland: findings from National Blood Pressure Week 2009

Background

The Swiss Health Survey (SHS) provides the only source of data for monitoring overweight and obesity in the general population in Switzerland. However, this survey reports body mass index (BMI) based on self-reported height and weight, and is therefore subject to measurement errors. Moreover, it is not possible to differentiate between overall and abdominal overweight. In this study, we aimed to gain a better understanding of the need for weight management in the general population of Switzerland by exploring and comparing prevalence rates of BMI and waist circumference (WC) based on physical measurements by trained observers, based on data from the 2009 National Blood Pressure Week (NBPW).

Methods

Sample selection was based on a one-stage cluster design. A total of 385 pharmacies representing 3,600 subjects were randomly selected from pharmacies participating in NBPW. BMI measures based on physical weight and height (NBPW) were compared with self-reported BMI measures from the SHS. BMI and WC measurements from NBPW were then used to produce population estimates of overweight and obesity.

Results

BMI-based overall prevalence of overweight and obesity was 43.6%, which was 4.7% higher than the value based on the respective SHS data. Overweight and obesity were more common in men (54.3%) than in women (33.5%). However, the overall prevalence of increased WC in the general population was estimated to be 64.4%, with more women (68.4%) than men (60.1%) exhibiting a WC above the threshold. The prevalence of subjects requiring weight management in the Swiss population remained high, even after adjusting WC for false positive and negative cases.

Conclusions

Firstly, it may be more appropriate for health promotion programs to address the wider group identified by WC, which includes subjects who need to reduce their weight, or gain no further weight. Secondly, the gender differences are reversed depending on the use of WC or BMI to identify subjects suitable for health promotion programs; more women than men are identified by WC, and more men than women using BMI. These differences should be accounted for in gender-specific health promotion programs.