Estimating the proportion of metabolic health outcomes attributable to obesity: a cross-sectional exploration of body mass index and waist circumference combinations

BACKGROUND: Recent evidence suggests that a substantial subgroup of the population who have a high-risk waist circumference (WC) do not have an obese body mass index (BMI). This study aimed to explore whether including those with a non-obese BMI but high risk WC as 'obese' improves prediction of adiposity-related metabolic outcomes.

METHODS: Eleven thousand, two hundred forty-seven participants were recruited. Height, weight and WC were measured. Ten thousand, six hundred fifty-nine participants with complete data were included. Adiposity categories were defined as: BMI(N)/WC(N), BMI(N)/WC(O), BMI(O)/WC(N), and BMI(O)/WC(O) (N = non-obese and O = obese). Population attributable fraction, area under the receiver operating characteristic curve (AUC), and odds ratios (OR) were calculated.

RESULTS: Participants were on average 48 years old and 50 % were men. The proportions of BMI(N)/WC(N), BMI(N)/WC(O), BMI(O)/WC(N) and BMI(O)/WC(O) were 68, 12, 2 and 18 %, respectively. A lower proportion of diabetes was attributable to obesity defined using BMI alone compared to BMI and WC combined (32 % vs 47 %). AUC for diabetes was also lower when obesity was defined using BMI alone (0.62 vs 0.66). Similar results were observed for all outcomes. The odds for hypertension, dyslipidaemia, diabetes and CVD were increased for those with BMI(N)/WC(O) (OR range 1.8-2.7) and BMI(O)/WC(O) (OR 1.9-4.9) compared to those with BMI(N)/WC(N).

CONCLUSIONS: Current population monitoring, assessing obesity by BMI only, misses a proportion of the population who are at increased health risk through excess adiposity. Improved identification of those at increased health risk needs to be considered for better prioritisation of policy and resources.

The extended Infant Feeding, Activity and Nutrition Trial (InFANT Extend) Program : a cluster-randomized controlled trial of an early intervention to prevent childhood obesity

BACKGROUND: Understanding how we can prevent childhood obesity in scalable and sustainable ways is imperative. Early RCT interventions focused on the first two years of life have shown promise however, differences in Body Mass Index between intervention and control groups diminish once the interventions cease. Innovative and cost-effective strategies seeking to continue to support parents to engender appropriate energy balance behaviours in young children need to be explored. METHODS/DESIGN: The Infant Feeding Activity and Nutrition Trial (InFANT) Extend Program builds on the early outcomes of the Melbourne InFANT Program. This cluster randomized controlled trial will test the efficacy of an extended (33 versus 15 month) and enhanced (use of web-based materials, and Facebook® engagement), version of the original Melbourne InFANT Program intervention in a new cohort. Outcomes at 36 months of age will be compared against the control group. DISCUSSION: This trial will provide important information regarding capacity and opportunities to maximize early childhood intervention effectiveness over the first three years of life. This study continues to build the evidence base regarding the design of cost-effective, scalable interventions to promote protective energy balance behaviors in early childhood, and in turn, promote improved child weight and health across the life course. TRIAL REGISTRATION: ACTRN12611000386932 . Registered 13 April 2011.

Physical activity, screen-based behaviours and obesity among Fijian adolescents

 This PhD investigated obesity and mental health issues. Physical activity, screen-based behaviour (including e-gaming) measures don’t seem to be closely linked to BMI-z or psychosocial outcomes in Fijian adolescents. Expectations of the BMI-z impact of PA programs should be low and control on violent e-gaming through licensing agreements is suggested.

Interventions for treating obesity in children (Review)

Childhood obesity affects both the physical and psychosocial health of children and may put them at risk of ill health as adults. The number of obese children in developed countries is increasing dramatically. There are many different lifestyle change programmes to help parents and children control their weight. Although 18 research studies were found, most of these were very small studies and so evidence from them is limited. In conclusion, there is a limited amount of quality data on the effects of programs to treat childhood obesity, and as such no conclusions can be drawn with confidence.

Management of obesity: attitudes and practices of Australian dietitians

OBJECTIVE: To document attitudes and current practices of Australian dietitians in the management of overweight and obesity, and to examine their training needs.

DESIGN: Cross-sectional postal survey of a randomly selected sample of members of the Dietitians Association of Australia.

SUBJECTS: 400 dietitians (66% of those surveyed).

MEASURES: Questionnaire-based measures of dietitian's views of obesity, education and training in weight management, definitions and perceptions of success, professional preparedness, approaches to weight management, strategies recommended for weight management, and problems and frustrations experienced.

RESULTS: Dietitians viewed themselves as potential leaders in the field of weight management, and saw this area as an important part of their role. While they considered themselves to be the best-trained professionals in this area, many felt that their training was poor and many were pessimistic about intervention outcomes. Despite this, most dietitians held views that were current, and regularly employed many of the elements of known best practice in management. However, important areas of weakness included: providing opportunities for long-term follow-up; providing a range of management interventions; promoting self-monitoring of diet and exercise; and promoting opportunities for social support.

CONCLUSIONS: This study suggests that training in and advocacy for the management and prevention of overweight and obesity are priority areas for dietitians, and that formal studies to evaluate dietitians' effectiveness in management should be undertaken.

Obesity management: Australian general practitioners' attitudes and practices

Objectives: To document general practitioners’ (GPs) attitudes and practices regarding the prevention and management of overweight and obesity.

Research Methods and Procedures: A cross-sectional survey of a randomly selected sample of 1500 Australian GPs was conducted, of which 752 questionnaires were returned. The measures included views on weight management, definitions of success, views regarding the usefulness of drugs, approaches to and strategies recommended for weight management, and problems and frustrations in managing overweight and obesity.

Results: GPs view weight management as important and feel they have an important role to play. Although they consider themselves to be well prepared to treat overweight patients, they believe that they have limited efficacy in weight management and find it professionally unrewarding. GPs view the assessment of a patient's dietary and physical activity habits and the provision of dietary and physical activity advice as very important. The approaches least likely to be considered important and/or least likely to be practiced were those that would support the patient in achieving and maintaining lifestyle change.

Discussion: There remains considerable opportunity to improve the practice of GPs in their management of overweight and obesity. Although education is fundamental, it is important to acknowledge the constraints of the GPs’ existing working environment.

Prevention of childhood obesity

Childhood obesity is a complex disease with different genetic, metabolic, environmental and behavioural components that are interrelated and potentially confounding, thus making causal pathways difficult to define. Given the tracking of obesity and the associated risk factors, childhood is an important period for prevention. To date, evidence would support preventative interventions that encourage physical activity and a healthy diet, restrict sedentary activities and offer behavioural support. However, these interventions should involve not only the child but the whole family, school and community. If the current global obesity epidemic is to be halted, further large-scale, well-designed prevention studies are required, particularly within settings outside of the USA, in order to expand the currently limited evidence base upon which clinical recommendations and public health approaches can be formulated. This must be accompanied by enhanced monitoring of paediatric obesity prevalence and continued support from all stakeholders at global, national, regional and local levels.

24-h urinary sodium excretion is associated with obesity in a cross-sectional sample of Australian schoolchildren

Emerging evidence indicates that dietary Na may be linked to obesity; however it is unclear whether this relationship is independent of energy intake (EI). The aim of this study was to assess the association between Na intake and measures of adiposity, including BMI z score, weight category and waist:height ratio (WHtR), in a sample of Australian schoolchildren. This was a cross-sectional study of schoolchildren aged 4-12 years. Na intake was assessed via one 24-h urine collection. BMI was converted to age- and sex-specific z scores, and WHtR was used to define abdominal obesity. In children aged ≥8 years, EI was determined via one 24-h dietary recall. Of the 666 children with valid urine samples 55 % were male (average age 9·3 (sd 1·8) years). In adjusted models an additional 17 mmol/d of Na was associated with a 0·10 higher BMI z score (95 % CI 0·07, 0·13), a 23 % (OR 1·23; 95 % CI 1·16, 1·31) greater risk of being overweight/obese and a 15 % (OR 1·15; 95 % CI 1·09, 1·23) greater risk of being centrally obese. In the subsample of 8-12-year-old children (n 458), adjustment for EI did not markedly alter the associations between Na and adiposity outcomes. Using a robust measure of daily Na intake we found a positive association between Na intake and obesity risk in Australian schoolchildren, which could not be explained by total energy consumption. To determine whether this is a causal relationship, longitudinal studies, with high-quality measures of Na and EI, are required.

Healthy together Victoria and childhood obesity-a methodology for measuring changes in childhood obesity in response to a community-based, whole of system cluster randomized control trial

BACKGROUND: Healthy Together Victoria (HTV) - a complex 'whole of system' intervention, including an embedded cluster randomized control trial, to reduce chronic disease by addressing risk factors (physical inactivity, poor diet quality, smoking and harmful alcohol use) among children and adults in selected communities in Victoria, Australia (Healthy Together Communities).

OBJECTIVES: To describe the methodology for: 1) assessing changes in the prevalence of measured childhood obesity and associated risks between primary and secondary school students in HTV communities, compared with comparison communities; and 2) assessing community-level system changes that influence childhood obesity in HTC and comparison communities.

METHODS: Twenty-four geographically bounded areas were randomized to either prevention or comparison (2012). A repeat cross-sectional study utilising opt-out consent will collect objectively measured height, weight, waist and self-reported behavioral data among primary [Grade 4 (aged 9-10y) and Grade 6 (aged 11-12y)] and secondary [Grade 8 (aged 13-14y) and Grade 10 (aged 15-16y)] school students (2014 to 2018). Relationships between measured childhood obesity and system causes, as defined in the Foresight obesity systems map, will be assessed using a range of routine and customised data.

CONCLUSION: This research methodology describes the beginnings of a state-wide childhood obesity monitoring system that can evolve to regularly inform progress on reducing obesity, and situate these changes in the context of broader community-level system change.

Sleep duration and risk of obesity among a sample of Victorian school children

BACKGROUND: Insufficient sleep is potentially an important modifiable risk factor for obesity and poor physical activity and sedentary behaviours among children. However, inconsistencies across studies highlight the need for more objective measures. This paper examines the relationship between sleep duration and objectively measured physical activity, sedentary time and weight status, among a sample of Victorian Primary School children.

METHODS: A sub-sample of 298 grades four (n = 157) and six (n = 132) Victorian primary school children (aged 9.2-13.2 years) with complete accelerometry and anthropometry data, from 39 schools, were taken from a pilot study of a larger state based cluster randomized control trial in 2013. Data comprised: researcher measured height and weight; accelerometry derived physical activity and sedentary time; and self-reported sleep duration and hypothesised confounding factors (e.g. age, gender and environmental factors).

RESULTS: Compared with sufficient sleepers (67 %), those with insufficient sleep (<10 hrs/day) were significantly more likely to be overweight (OR 1.97, 95 % CI:1.11-3.48) or obese (OR 2.43, 95 % CI:1.26-4.71). No association between sleep and objectively measured physical activity levels or sedentary time was found.

CONCLUSION: The strong positive relationship between weight status and sleep deprivation merits further research though PA and sedentary time do not seem to be involved in the relationship. Strategies to improve sleep duration may help obesity prevention initiatives in the future.

Empowering primary care to tackle the obesity epidemic: the Counterweight Programme

Subjects: Obese patients (body mass index greater than or equal to30 kg/m2) or BMIgreater than or equal to28 kg/m2 with obesity-related comorbidities in 80 general practices.

Intervention: The model consists of four phases: (1) audit and project development, (2) practice training and support, (3) nurse-led patient intervention, and (4) evaluation. The intervention programme used evidence-based pathways, which included strategies to empower clinicians and patients. Weight Management Advisers who are specialist obesity dietitians facilitated programme implementation.

Main outcome measures: Proportion of practices trained and recruiting patients, and weight change at 12 months.

Results: By March 2004, 58 of the 62 (93.5%) intervention practices had been trained, 47 (75.8%) practices were active in implementing the model and 1549 patients had been recruited. At 12 months, 33% of patients achieved a clinically meaningful weight loss of 5% or more. A total of 49% of patients were classed as 'completers' in that they attended the requisite number of appointments in 3, 6 and 12 months. 'Completers' achieved more successful weight loss with 40% achieving a weight loss of 5% or more at 12 months.

Conclusion: The Counterweight programme provides a promising model to improve the management of obesity in primary care.

Sponsorship: Educational grant-in-aid from Roche Products Ltd.

Obesity impacts on general practice appointments

Objective: To quantify the impact of obesity on the number of visits to both primary and secondary care teams.

Research Methods and Procedures: The adult populations of 80 general practices throughout the United Kingdom were classified according to their BMI. We undertook a cross-sectional survey of computer-generated and handwritten records of 6150 obese people (BMI ≥ 30 kg/m2) and 1150 normal weight (BMI = 18.5 to 24.9 kg/m2) control subjects over an 18-month retrospective period.

Results: Obese patients made significantly more visits to the general practitioner (GP), practice nurse (PN), and hospital outpatient units than normal weight patients (all p < 0.001), and they were admitted to the hospital more often (p = 0.034). For both GP and PN visits, the relationship remained after adjusting for age, sex, social deprivation category, country, and number of comorbidities. Among obese patients, there was an increasing relationship between frequent GP visits (at least four appointments) and greater BMI, which remained significant after adjustment had been made for age, sex, deprivation, country, and number of comorbidities.

Discussion: The human resource burden to general practice is significantly higher in the obese population than in the normal weight population, even when adjusted for confounding factors. The increase in prevalence of obesity will continue to put pressure on GP and PN time unless appropriate action is taken.

The impact of obesity on drug prescribing in primary care

Background

Healthcare costs attributable to obesity have previously involved estimations based on costs of diseases commonly considered as having obesity as an underlying factor.

Aim

To quantify the impact of obesity on total primary care drug prescribing.

Design of study

Review of computer generated and handwritten prescriptions to determine total prescribing volume for all drug classes.

Setting

Twenty-three general practice surgeries in the UK.

Method

Stratified random selection of 1150 patients who were obese (body mass index [BMI]>30 kg/m2) and 1150 age- and sex-matched controls of normal weight (BMI 18.5–<25 kg/m2). Retrospective review of medical records over an 18-month period.

Results

A higher percentage of patients who were obese, compared with those of normal weight, were prescribed at least one drug in the following disease categories: cardiovascular (36% versus 20%), central nervous system (46% versus 35%), endocrine (26% versus 18%), and musculoskeletal and joint disease (30% versus 22%). All of these categories had a P-value of <0.001. Other categories, such as gastrointestinal (24% versus 18%), infections (42% versus 35%), skin (24% versus 19%) had a P-value of <0.01, while respiratory diseases (18% versus 21%) had a P-value of <0.05. Total prescribing volume was significantly higher for the group with obesity and was increased in the region of two- to fourfold in a wide range of prescribing categories: ulcer healing drugs, lipid regulators, β-adrenoreceptor drugs, drugs affecting the rennin angiotensin system, calcium channel blockers, antibacterial drugs, sulphonylureas, biguanides, non-steroidal anti-inflammatories (NSAIDs) (P<0.001) and fibrates, angiotensin II antagonists, and thyroid drugs (P<0.05). The main impact on prescribing volumes is from numbers of patients treated, although in some areas there is an effect from greater dosage or longer treatment in those who are obese including calcium channel blockers, antihistamines, hypnotics, drugs used in the treatment of nausea and vertigo, biguanides, and NSAIDs (P<0.05) reflected in significantly increased defined daily dose prescribing.

Current approaches to obesity management in UK Primary Care: the Counterweight Programme

Background/Aims Primary care is expected to develop strategies to manage obese patients as part of coronary heart disease and diabetes national service frameworks. Little is known about current management practices for obesity in this setting. The aim of this study is to examine current approaches to obesity management in UK primary care and to identify potential gaps in care.

Method A total of 141 general practitioners (GPs) and 66 practice nurses (PNs) from 40 primary care practices participated in structured interviews to examine clinician self-reported approaches to obesity management. Medical records were also reviewed for 100 randomly selected obese patients from each practice [body mass index (BMI) ≥30 kg m−2, n = 4000] to review rates of diet counselling, dietetic or obesity centre referrals, and use of anti-obesity medication. Computerized medical records for the total practice population (n = 206 341, 18–75 years) were searched to examine the proportion of patients with a weight/BMI ever recorded.

Results Eighty-three per cent of GPs and 97% of PNs reported that they would raise weight as an issue with obese patients (P < 0.01). Few GPs (15%) reported spending up to 10 min in a consultation discussing weight-related issues, compared with PNs (76%; P < 0.001). Over 18 months, practice-based diet counselling (20%), dietetic (4%) and obesity centre (1%) referrals, and any anti-obesity medication (2%) were recorded. BMI was recorded for 64.2% of patients and apparent prevalence of obesity was less than expected.

Conclusion Obesity is under-recognized in primary care even in these 40 practices with an interest in weight management. Weight management appears to be based on brief opportunistic intervention undertaken mainly by PNs. While clinicians report the use of external sources of support, few patients are referred, with practice-based counselling being the most common intervention.