Comparisons of Measured and Self-Reported Anthropometric Variables and Blood Pressure in a Sample of Hong Kong Female Nurses

Objectives

To assess the validity of self-reported weight, height, body mass index (BMI), waist circumference and blood pressure compared with standardized clinical measurements and to determine the classification accuracy in overweight/obesity and central adiposity.

Methods

This pilot study was integrated into a life-course study entitled “Hong Kong Women''s Health Study” among 1,253 female nurses in Hong Kong who were aged 35 years to 65 years. Data were collected from self-administered questionnaires that were mailed to the respondents. Of these participants, we obtained the standard body measurements of 144 (11.5%) at our research center. We then compared the self-reported anthropometric variables and blood pressure with the measured data to assess validity based on the level of misreporting, percentage of agreement, consistency, sensitivity and specificity.

Results

The self-reported and measured values were highly correlated in terms of anthropometry and blood pressure (correlation coefficients ranged from 0.72 to 0.96). Height was overestimated at an average of 0.42 cm, and waist circumference was underestimated at 2.33 cm (both P<0.05), while no significant differences were observed from weight, blood pressure and BMI (all P>0.05). The proportions of overweight, obesity, and central adiposity by self-reported data did not vary greatly from the measured data (all P>0.05). The self-reporting resulted in correct classifications of BMI, waist circumference, and systolic blood pressure in 85%, 78%, and 87% of women, with corresponding Kappa index values of 0.79, 0.55, and 0.82, respectively. Sensitivity and specificity were 84.6% and 95.7%, respectively, with respect to overweight/obesity detection, whereas those for central adiposity detection were 70.6% and 83.8%, respectively.

Conclusion

In a sample of female Hong Kong nurses, the self-reported measures of height, weight, BMI, waist circumference and blood pressure were generally valid. Furthermore, the classification accuracies of overweight/obesity and central adiposity were acceptable.     

Association between non-suicidal self-injuries and suicide attempts in Chinese adolescents and college students: a cross-section study

Purpose

This study examined the association between non-suicidal self-injury (NSSI) and suicide attempts among Chinese adolescents and college students.

Methods

A total sample of 2013 Chinese students were randomly selected from five schools in Wuhan, China, including 1101 boys and 912 girls with the age ranging between 10 and 24 years. NSSI, suicidal ideation, suicide attempts and depressive symptoms were measured by self-rated questionnaires. Self-reported suicide attempts were regressed on suicidal ideation and NSSI, controlling for participants'' depressive symptoms, and demographic characteristics.

Results

The self-reported prevalence rates of NSSI, suicidal ideation, suicide attempts were 15.5%, 8.8%, and 3.5%, respectively. Logistic regression analyses indicated that NSSI was significantly associated with self-reported suicide attempts. Analyses examining the conditional association of NSSI and suicidal ideation with self-reported suicide attempts revealed that NSSI was significantly associated with greater risk of suicide attempts in those not reporting suicidal ideation than those reporting suicidal ideation in the past year.

Conclusions

These findings highlight the importance of NSSI as a potentially independent risk factor for suicide attempts among Chinese/Han adolescents and college students.     

Trends in Prevalence of Overweight and Obesity in Danish Infants,Children and Adolescents – Are We Still on a Plateau?

Background

After the worldwide steep increase in child and adolescent overweight and obesity during the last decades, there is now evidence of a levelling off in the prevalence in many countries in the Western world.

Aim

To examine whether there still is a plateau in the prevalence of overweight and obesity in Danish children and adolescents, or whether the prevalence is decreasing or rising again.

Methods

The trends in the prevalence rates were based on three data sets providing comparable repeated estimates: 1) the Danish Health Visitors Child Health Database (DHVCHD) with measurements on infant and childhood height and weight from 2002 to 2011 (n up to 39,984), 2) the Danish National Birth Cohort (DNBC) with maternal reports of measured infant and childhood height and weight from 1998 to 2010 (n up to 56,826) and 3) the Danish part of the Health Behaviour in School-aged Children survey (HBSC) with self-reported information on adolescent height and weight from the years 2002 to 2010 (n = 16,557). Overweight and obesity were categorized according to WHO growth standards. Trends were assessed by repeated point estimates and linear regression analyses providing regression coefficients for changes in per cent per year with 95% confidence intervals (CI).

Results

The prevalence rates of overweight and obesity for infants, children and adolescents showed a mixed pattern of decline, stability and increase (ranging from -1.10 through 0.29 per cent per year with CI’s from -3.10 through 2.37). Overall, there were no consistent statistically significant trends upwards or downwards, although some significant downward trends in childhood and adolescence were observed.

Conclusion

This study, based on data from 1998 through 2011, showed that the prevalence rates of overweight and obesity among Danish infants, children and adolescents were largely still on a plateau with tendencies for a decline among children and adolescents.     

Outcomes of Ethnic Minority Groups with Node-Positive,Non-Metastatic Breast Cancer in Two Tertiary Referral Canters in Sydney,Australia

Purpose

There is a lack of information in ethnic minority groups with regard to presentation and treatment of early node-positive breast cancer. We carried out a retrospective study of patients referred to two tertiary cancer centers in South Western Sydney, both of which serve a high proportion of this ethnic minority population.

Patients and methods

Women who had pathologically node-positive non-metastatic breast cancer (T1-3, N1-3, M0) diagnosed between 2003 and 2006 were studied, with variables of interest being tumor size, number of positive nodes, histological grade, hormone receptor status, age at diagnosis, country of birth and treatment. We compared the Asian and Western subgroups with regard to tumor characteristics, treatment and clinical outcomes.

Results

A total of 652 eligible patients were identified, with a median follow-up of 6.1 years. Women with Asian backgrounds (n = 125, 20%) were significantly younger at presentation (48 years versus 55 years, p-value <0.0001) and more likely to undergo mastectomy (53% versus 39%, p-value 0.0009) and chemotherapy (86% versus 72%, p-value 0.0063) than their non-Asian counterparts. Tumor stage, grade and receptor status were not statistically different between these two groups. There were also no differences in disease-free survival and overall survival, with medians of 12.7 and 14.8 years respectively.

Conclusion

Women of Asian background are younger at diagnosis, which may reflect population epidemiology and likely results in higher uptake of chemotherapy. Higher mastectomy rates may be influenced by cultural factors. Future research is warranted to investigate potential differences in tumor biology, psychosocial, economic and cultural factors.     

Secular Trends in Growth and Nutritional Status of Mozambican School-Aged Children and Adolescents

Objectives

The purpose of this study was to examine secular changes in growth and nutritional status of Mozambican children and adolescents between 1992, 1999 and 2012.

Methods

3374 subjects (1600 boys, 1774 girls), distributed across the three time points (523 subjects in 1992; 1565 in 1999; and 1286 in 2012), were studied. Height and weight were measured, BMI was computed, and WHO cut-points were used to define nutritional status. ANCOVA models were used to compare height, weight and BMI across study years; chi-square was used to determine differences in the nutritional status prevalence across the years.

Results

Significant differences for boys were found for height and weight (p<0.05) across the three time points, where those from 2012 were the heaviest, but those in 1999 were the tallest, and for BMI the highest value was observed in 2012 (1992<2012, 1999<2012). Among girls, those from 1999 were the tallest (1992<1999, 1999>2012), and those from 2012 had the highest BMI (1999<2012). In general, similar patterns were observed when mean values were analyzed by age. A positive trend was observed for overweight and obesity prevalences, whereas a negative trend emerged for wasting, stunting-wasting (in boys), and normal-weight (in girls); no clear trend was evident for stunting.

Conclusion

Significant positive changes in growth and nutritional status were observed among Mozambican youth from 1992 to 2012, which are associated with economic, social and cultural transitional processes, expressing a dual burden in this population, with reduction in malnourished youth in association with an increase in the prevalence of overweight and obesity.     

Brazilian Pediatric Reference Data for Quantitative Ultrasound of Phalanges According to Gender,Age, Height and Weight

Aims

To establish normative data for phalangeal quantitative ultrasound (QUS) measures in Brazilian students.

Methods

The sample was composed of 6870 students (3688 females and 3182 males), aged 6 to 17 years. The bone status parameter, Amplitude Dependent Speed of Sound (AD-SoS) was assessed by QUS of the phalanges using DBM Sonic BP (IGEA, Carpi, Italy) equipment. Skin color was obtained by self-evaluation. The LMS method was used to derive smoothed percentiles reference charts for AD-SoS according to sex, age, height and weight and to generate the L, M, and S parameters.

Results

Girls showed higher AD-SoS values than boys in the age groups 7–16 (p<0.001). There were no differences on AD-SoS Z-scores according to skin color. In both sexes, the obese group showed lower values of AD-SoS Z-scores compared with subjects classified as thin or normal weight. Age (r² = 0.48) and height (r² = 0.35) were independent predictors of AD-SoS in females and males, respectively.

Conclusion

AD-SoS values in Brazilian children and adolescents were influenced by sex, age and weight status, but not by skin color. Our normative data could be used for monitoring AD-SoS in children or adolescents aged 6–17 years.     

Life events, coping, and posttraumatic stress symptoms among Chinese adolescents exposed to 2008 Wenchuan Earthquake, China

Purpose

To examine the relationship between negative life events, coping styles, and symptoms of post-traumatic stress disorder (PTSD) among adolescent survivors exposed to 2008 Wenchuan Earthquake, China.

Methods

A survey was conducted in a sample of 2250 adolescent students from two schools in Dujiangyan District, a seriously damaged area, 20 kilometers away from the epicenter, 6 months after the earthquake. Participants completed a self-administered questionnaire including demographics, negative life events, coping styles, and PTSD symptoms.

Results

Academic pressure was the strongest predictor of adolescents'' PTSD symptoms among all negative life events. Main effects of negative life events, positive coping and negative coping on PTSD symptoms were significant in both younger adolescents and older adolescents, while the moderator effects of two coping styles were found significant only within older adolescents.

Conclusions

Coping may play a role to moderate the relationship between post-earthquake negative life events and PTSD symptom, but the function seems to depend on the age of participants. Psychosocial coping skills training may be important in the prevention and intervention of mental health problems in adolescent survivors of traumatic earthquake.     

Serum Acylated Ghrelin Concentrations in Response to Short-Term Overfeeding in Normal Weight,Overweight, and Obese Men

Background

Ghrelin, an orexigenic gut hormone secreted primarily from the stomach, is involved in energy homeostasis. However, little data is available regarding its response to energy surplus and the development of human obesity.

Objective

The present study investigated the response of circulating acylated ghrelin to a 7-day positive energy challenge.

Design

A total of 68 healthy young men were overfed 70% more calories than required, for 1-week. Subjects were classified based on percent body fat (measured by dual-energy X-ray absorptiometry) as normal weight, overweight, and obese. Serum acylated ghrelin concentration was measured before and after the positive energy challenge. Additionally, the relationship between acylated ghrelin and obesity-related phenotypes including weight, body mass index, percent body fat, cholesterol, HDL-c, LDL-c, glucose, insulin and homeostasis model assessment of insulin resistance and β-cell function at baseline and change due to overfeeding, were assessed.

Results

Contrary to our expectations, serum acylated ghrelin was significantly increased in response to overfeeding and the increase was independent of obesity status. There was no significant difference in fasting acylated ghrelin between normal weight, overweight, and obese men at baseline. Acylated ghrelin was negatively correlated with weight and BMI for normal weight and with BMI in overweight men. Also ghrelin was correlated with change in weight and BMI in overweight (negative relationship) and obese (positive relationship) groups.

Conclusion

Our results showed that circulating acylated ghrelin was increased after a 7-day positive energy challenge regardless of adiposity status. However, acylated ghrelin was correlated with change in weight and BMI in opposing directions, in overweight and obese subjects respectively, thus dependent on obesity status.     

An Investigation into the Strength of the Association and Agreement Levels between Subjective and Objective Sleep Duration in Adolescents

Study Objectives

The majority of adolescent sleep research has utilized self-reported sleep duration and some have based information on a solitary question. Whilst some have claimed to have validated sleep survey data with objective actigraphy measures in adolescents, the statistical approach applied only demonstrates the strength of the association between subjective and objective sleep duration data and does not reflect if these different methods actually agree.

Methods

Data were collected as part of the Midlands Adolescents Schools Sleep Education Study (MASSES). Adolescents (n=225) aged 11-13 years provided estimates for weekday, weekend and combined sleep duration based on self-reported survey data, a 7-day sleep diary, and wrist-worn actigraphy.

Results

We assessed the strength of the relationship as well as agreement levels between subjective and objectively determined sleep duration (weekday, weekend and combined). Subjective diary sleep duration was significantly correlated with actigraphy estimates for weekday and weekend sleep duration r=0.30, p≤0.001 and r=0.31, p≤0.001 respectively. Pitman’s test demonstrated no significant difference in the variance between weekend sleep duration (r=0.09, p=0.16) and combined sleep duration (r=0.12, p=0.08) indicating acceptable agreement between actigraphy and sleep diary sleep duration only. Self-reported sleep duration estimates (weekday, weekend and combined) did not agree with actigraphy determined sleep duration.

Conclusions

Sleep diaries are a cost-effective alternative to survey/questionnaire data. Self-reported measures of sleep duration in adolescents do not agree with actigraphy measures and should be avoided where possible. Previous adolescent sleep studies that have utilized self-reported survey data may not provide a complete representation of sleep on the outcome measure of interest.     

HIV Status Disclosure to Perinatally-Infected Adolescents in Zimbabwe: A Qualitative Study of Adolescent and Healthcare Worker Perspectives

Introduction & Objectives

Due to the scale up of antiretroviral therapy, increasing numbers of HIV-infected children are living into adolescence. As these children grow and surpass the immediate threat of death, the issue of informing them of their HIV status arises. This study aimed to understand how perinatally-infected adolescents learn about their HIV-status as well as to examine their preferences for the disclosure process.

Methods

In-depth interviews were conducted with 31 (14 male, 17 female) perinatally-infected adolescents aged 16–20 at an HIV clinic in Harare, Zimbabwe, and focused on adolescents'' experiences of disclosure. In addition, 15 (1 male, 14 female) healthcare workers participated in two focus groups that were centred on healthcare workers'' practices surrounding disclosure in the clinic. Purposive sampling was used to recruit participants. A coding frame was developed and major themes were extracted using grounded theory methods.

Results

Healthcare workers encouraged caregivers to initiate disclosure in the home environment. However, many adolescents preferred disclosure to take place in the presence of healthcare workers at the clinic because it gave them access to accurate information as well as an environment that made test results seem more credible. Adolescents learned more specific information about living with an HIV-positive status and the meaning of that status from shared experiences among peers at the clinic.

Conclusions

HIV-status disclosure to adolescents is distinct from disclosure to younger children and requires tailored, age-appropriate guidelines. Disclosure to this age group in a healthcare setting may help overcome some of the barriers associated with caregivers disclosing in the home environment and make the HIV status seem more credible to an adolescent. The study also highlights the value of peer support among adolescents, which could help reduce the burden of psychosocial care on caregivers and healthcare workers.     

The Association of Longitudinal and Interpersonal Continuity of Care with Emergency Department Use,Hospitalization, and Mortality among Medicare Beneficiaries

Background

Continuity of medical care is widely believed to lead to better health outcomes and service utilization patterns for patients. Most continuity studies, however, have only used administrative claims to assess longitudinal continuity with a provider. As a result, little is known about how interpersonal continuity (the patient''s experience at the visit) relates to improved health outcomes and service use.

Methods

We linked claims-based longitudinal continuity and survey-based self-reported interpersonal continuity indicators for 1,219 Medicare beneficiaries who completed the National Health and Health Services Use Questionnaire. With these linked data, we prospectively evaluated the effect of both types of continuity of care indicators on emergency department use, hospitalization, and mortality over a five-year period.

Results

Patient-reported continuity was associated with reduced emergency department use, preventable hospitalization, and mortality. Most of the claims-based measures, including those most frequently used to assess continuity, were not associated with reduced utilization or mortality.

Conclusion

Our results indicate that the patient- and claims-based indicators of continuity have very different effects on these important health outcomes, suggesting that reform efforts must include the patient-provider experience when evaluating health care quality.     

Effectiveness of YouRAction, an intervention to promote adolescent physical activity using personal and environmental feedback: a cluster RCT

Background

In this study the one and six months effects of the computer-tailored YouRAction (targeting individual level determinants) and YouRAction+e (targeting in addition perceived environmental determinants) on compliance with the moderate-to-vigorous physical activity (MVPA) guideline and weight status are examined. In addition the use and appreciation of both interventions are studied.

Methods

A three-armed cluster randomized trial was conducted in 2009–2010 with measurements at baseline, one and six months post intervention. School classes were assigned to one of the study arms (YouRaction, YouRAction+e and Generic Information (GI) control group). MVPA was derived from self-reports at baseline, one and six months post intervention. Body Mass Index and waist circumference were measured at baseline and six months post intervention in a random sub-sample of the population. Use of the interventions was measured by webserver logs and appreciation by self-reports. Multilevel regression analyses were conducted to study the effects of the intervention against the GI control group. ANOVA''s and chi-square tests were used to describe differences in use and appreciation between study arms.

Results

There were no statistically significant intervention effects on compliance with the MVPA guideline, overweight or WC. Access to the full intervention was significantly lower for YouRAction (24.0%) and YouRAction+e (21.7%) compared to the GI (54.4%).

Conclusion

This study could not demonstrate that the YouRAction and YouRAction+e interventions were effective in promoting MVPA or improve anthropometric outcomes among adolescents, compared to generic information. Insufficient use and exposure to the intervention content may be an explanation for the lack of effects.

Trial Registration

TrialRegister.nl NTR1923     

Variables Associated with Change in Quality of Life among Persons with Dementia in Nursing Homes: A 10 Months Follow-Up Study

Aim

To investigate variables associated with change in quality of life (QOL), measured by QUALID scale and three subscales; tension, sadness and wellbeing, among dementia patients in nursing homes.

Method

A 10 months follow-up study including 198 (female 156, 79%) nursing home patients, mean age 87 (s.d 7.7) years. Scales applied; quality of life in late stage dementia (QUALID) scale and three subscales (wellbeing, sadness and tension), neuropsychiatric inventory questionnaire 10 items (NPI-10-Q), clinical dementia rating (CDR) scale, physical self-maintenance (PSMS) scale and a scale of general medical health. Use of psychotropic medication, gender and age was collected from the patient''s records.

Results

Mean baseline QUALID score: 20.6 (s.d.7.0), follow-up score: 22.9 (s.d.7.4), mean change 2.8 (s.d.7.4). QOL improved in 30.8%, were unchanged in 14.7%, deteriorated in 54.6% of patients. A regression analysis revealed that change in QUALID score was significantly associated with: QUALID baseline score (beta -.381, p-value.000), change in NPI score (beta.421, p-value.000), explained variance 38.1%. Change in score on wellbeing subscale associated with: change in PSMS score (beta.185, p-value.019), wellbeing baseline score (beta -.370, p-value.000), change in NPI score (beta.186, p-value.017), explained variance 25.3%. Change in score on tension subscale associated with: change in CDR sum-of-boxes (beta.214, p-value.003), change in NPI score (beta.270, p-value.000), tension baseline score (beta -.423, p-value.000), explained variance 34.6%. Change in score on sadness subscale associated with: change in NPI score (beta.404, p-value.000), sadness baseline score (beta -.438, p-value.000), explained variance 38.8%.

Conclusion

The results imply that a lower baseline score (better QOL) results in a larger change in QOL (towards worse QOL). Change in QOL is mostly associated with change in neuropsychiatric symptoms. In almost 50% of patients QOL did not deteriorate.     

The Role of Tobacco,Alcohol, and Obesity in Neoplastic Progression to Esophageal Adenocarcinoma: A Prospective Study of Barrett's Esophagus

Background

Esophageal adenocarcinoma (EA) incidence in many developed countries has increased dramatically over four decades, while survival remains poor. Persons with Barrett''s esophagus (BE), who experience substantially elevated EA risk, are typically followed in surveillance involving periodic endoscopy with biopsies, although few progress to EA. No medical, surgical or lifestyle interventions have been proven to safely lower EA risk.

Design

We investigated whether smoking, obesity or alcohol could predict progression to EA in a prospective cohort of 411 BE patients. Data were collected during personal interview. Adjusted hazard ratios (HR) were estimated using Cox regression.

Results

39% had body mass index (BMI) over 30 and 64% had smoked cigarettes. Main analyses focused on those with at least 5 months of follow-up (33,635 person-months), in whom 45 developed EA. Risk increased by 3% per year of age (trend p-value 0.02), with approximate doubling of risk among males. EA risk increased with smoking pack-years (trend p-value 0.04) and duration (p-value 0.05). Compared to never-smokers, the HR for those in the highest pack-year tertile was 2.29 (95%CI 1.04–5.07). No association was found with alcohol or BMI, whereas a suggestion of increased risk was observed in those with higher waist-hip ratio, especially among males.

Conclusion

EA risk significantly increased with increasing age and cigarette exposure. Abdominal obesity, but not BMI, was associated with a modest increased risk. Continued follow-up of this and other cohorts is needed to precisely define these relationships so as to inform risk stratification and preventive interventions.     

Hostility, physical aggression and trait anger as predictors for suicidal behavior in Chinese adolescents: a school-based study

Purpose

This study explored the extent to which trait aggression is associated with suicidal behavior in a nationwide school-based sample of adolescents.

Methods

A nationwide sample of 14,537 high school students in urban areas of China was recruited. Information concerning suicide ideation, plans, attempts, trait aggression and other risk factors was collected by a self-reported questionnaire. Multivariate regression analyses were employed to predict suicidal behavior.

Results

Approximately 18.5% of students reported suicide ideation, 8.7% reported suicide plans, and 4.1% reported attempts during the past one year. Hostility and trait anger had a significant positive association with suicidal ideation. Hostility and physical aggression were positively related to suicide plans. Hostility had a positive correlation with suicide attempts, while trait anger was inversely associated with suicide attempts.

Conclusions

This study suggests that hostility, physical aggression and trait anger may be able to be used to predict suicidal behavior among adolescents. Suicide prevention programs should target at attenuating the severity of hostility, anger and physical aggression. But teachers and parents should also give close attention to students with low trait anger.     

The Association between Maltreatment in Childhood and Pre-Pregnancy Obesity in Women Attending an Antenatal Clinic in Australia

Introduction

Obesity in pregnancy is associated with increased risk of complications and adverse outcomes in mother and child. Childhood adverse experiences are known to have numerous negative physical and emotional sequelae. We aimed to examine if exposure to abuse and/or neglect in childhood increased the likelihood of pre-pregnancy obesity.

Methods

Demographic and clinical data including weight, height, mental health as measured by the General Health Questionnaire and exposure to childhood trauma as measured by the childhood trauma questionnaire was collected from 239 women attending antenatal care at an Australian tertiary hospital.

Results

More than one quarter of women were obese prior to pregnancy and approximately 20% of women self reported experiencing moderate to severe physical, sexual or emotional abuse. Almost 60% of women scored in the clinical range on the GHQ. Pre-pregnancy obesity in women attending antenatal care was associated with a self-reported history of emotional or physical abuse with those exposed to moderate or severe emotional or physical abuse having increased odds of being obese prior to pregnancy (O.R. and 95% CI: 2.40; 1.19–4.84 and 2.38; 1.18–4.79 respectively). There was no significant association between other forms of childhood maltreatment, demographic or current mental health status and pre-pregnancy obesity.

Conclusions

The high rates of obesity, mental health problems and self reported childhood maltreatment in the Australian antenatal population are serious public health concerns due to the extra health risks conferred on mother and offspring. Exposure to physical or emotional abuse during childhood increases the likelihood of obesity in women attending antenatal care. Further research is required to determine reasons for this association.     

Genetic and environmental contributions to weight, height, and BMI from birth to 19 years of age: an international study of over 12,000 twin pairs

Objective

To examine the genetic and environmental influences on variances in weight, height, and BMI, from birth through 19 years of age, in boys and girls from three continents.

Design and Settings

Cross-sectional twin study. Data obtained from a total of 23 twin birth-cohorts from four countries: Canada, Sweden, Denmark, and Australia. Participants were Monozygotic (MZ) and dizygotic (DZ) (same- and opposite-sex) twin pairs with data available for both height and weight at a given age, from birth through 19 years of age. Approximately 24,036 children were included in the analyses.

Results

Heritability for body weight, height, and BMI was low at birth (between 6.4 and 8.7% for boys, and between 4.8 and 7.9% for girls) but increased over time, accounting for close to half or more of the variance in body weight and BMI after 5 months of age in both sexes. Common environmental influences on all body measures were high at birth (between 74.1–85.9% in all measures for boys, and between 74.2 and 87.3% in all measures for girls) and markedly reduced over time. For body height, the effect of the common environment remained significant for a longer period during early childhood (up through 12 years of age). Sex-limitation of genetic and shared environmental effects was observed.

Conclusion

Genetics appear to play an increasingly important role in explaining the variation in weight, height, and BMI from early childhood to late adolescence, particularly in boys. Common environmental factors exert their strongest and most independent influence specifically in pre-adolescent years and more significantly in girls. These findings emphasize the need to target family and social environmental interventions in early childhood years, especially for females. As gene-environment correlation and interaction is likely, it is also necessary to identify the genetic variants that may predispose individuals to obesity.     

Weight-related behavior among adolescents: the role of peer effects

Purpose

To investigate whether social interactions in friendship networks influence the following weight-related behaviors of adolescents: exercising regularly, playing an active sport, hours of TV/Video viewing, sleeping six or fewer hours, eating breakfast on weekdays, frequency of eating at fast food restaurants, eating five servings of fruits/vegetables daily, and consuming calorie-dense snacks.

Method

Data from a nationally representative sample of adolescents are used to examine the association between peer and individual weight-related behaviors. Evidence from multivariate regression analysis controlling for an extensive list of individual- and family-level factors as well as school-level unobserved heterogeneity is obtained.

Results

We find a significant positive association between individuals'' and friends'' behaviors in terms of sports, exercise and fast food consumption. The estimated associations are robust to controls for individual- and family-level factors, unobserved heterogeneity at the school level and our attempts to account for non-random peer selection.

Conclusions

The social transmission of weight-related behaviors is a viable explanation for the spread of obesity in friendship networks documented in recent research. Traditional weight reduction interventions may be fruitfully complemented with strategies that focus on harnessing peer support to modify behaviors.     

Correction of Body-Mass Index Using Body-Shape Perception and Socioeconomic Status in Adolescent Self-Report Surveys

Objectives

To propose a simple correction of body-mass index (BMI) based on self-reported weight and height (reported BMI) using gender, body shape perception and socioeconomic status in an adolescent population.

Methods

341 boys and girls aged 17–18 years were randomly selected from a representative sample of 2165 French adolescents living in Paris surveyed in 2010. After an anonymous self-administered pen-and-paper questionnaire asking for height, weight, body shape perception (feeling too thin, about the right weight or too fat) and socioeconomic status, subjects were measured and weighed. BMI categories were computed according to Cole’s cut-offs. Reported BMIs were corrected using linear regressions and ROC analyses and checked with cross-validation and multiple imputations to handle missing values. Agreement between actual and corrected BMI values was estimated with Kappa indexes and Intraclass correlation coefficients (ICC).

Results

On average, BMIs were underreported, especially among girls. Kappa indexes between actual and reported BMI were low, especially for girls: 0.56 95%CI = [0.42–0.70] for boys and 0.45 95%CI = [0.30–0.60] for girls. The regression of reported BMI by gender and body shape perception gave the most balanced results for both genders: the Kappa and ICC obtained were 0.63 95%CI = [0.50–0.76] and 0.67, 95%CI = [0.58–0.74] for boys; 0.65 95%CI = [0.52–0.78] and 0.74, 95%CI = [0.66–0.81] for girls. The regression of reported BMI by gender and socioeconomic status led to similar corrections while the ROC analyses were inaccurate.

Conclusions

Using body shape perception, or socioeconomic status and gender is a promising way of correcting BMI in self-administered questionnaires, especially for girls.