Key Question 1 (KQ1). Do primary care-relevant prevention interventions (behaviourally-based) in normal weight adults lead to improved health outcomes or sustained/short-term weight gain prevention, with or without improved physiological measures?
a. How well is weight gain prevented or health outcomes maintained after an intervention is completed?
b. What are common elements of efficacious weight gain prevention interventions?
c. Are there differences in efficacy between adults subgroups (i.e., age 65 years or older; sex; race-ethnicity; baseline cardiovascular risk status)?
d. What are the adverse effects of primary care-relevant prevention in normal weight adults (e.g., labelling, disordered eating, psychological distress such as anxiety, depression and stigma, nutritional deficits and cost burden)?
e. Are there differences in adverse effects between adults subgroups (i.e., age 65 years or older; sex; race-ethnicity; baseline cardiovascular risk status)?
f. What risk assessment tools are identified in the literature to assess future health risk of obesity and which are the most effective in identifying those at higher risk of obesity?
Key Question 2 (KQ2). Do primary care-relevant prevention or treatment interventions (behaviourally-based and/or pharmacotherapy) in obese/overweight adults lead to improved health outcomes, short-term or sustained weight loss, or weight gain prevention, with or without improved physiological measures?
a. How well is weight loss or health outcomes maintained after an intervention is completed?
b. What are common elements of efficacious interventions (behaviourally-based and/or pharmacotherapy)?
c. Are there differences in efficacy between patient subgroups (i.e., age 65 years or older; sex; race-ethnicity; degree of obesity/overweight; baseline cardiovascular risk status)?
d. What are the adverse effects of primary care-relevant prevention or treatment interventions in obese/overweight adults (e.g., nutritional deficits, cardiovascular disease, bone mass loss, injuries, death, mental illness/psychological disorders)?
e. Are there differences in adverse effects between patient subgroups (i.e., age 65 years or older; sex; race-ethnicity; degree of obesity/overweight; baseline cardiovascular risk status)?
Key Question 3 (Adults of any weight)
a. What risk assessment tools are identified in the literature to assess future health risk as a result of obesity?
b. What risk assessment tools identified in the literature are available to identify those at higher risk of obesity and which are most effective?
a. Is there evidence that the burden of disease, the risk/benefit ratio of prevention or treatment, the optimal prevention or treatment method/access, and implementation differ in any ethnic subgroups or by age (pre-conception women), rural and remote populations, or lower SES populations?
b. What are the resource implications and cost effectiveness of overweight and obesity prevention/treatment in Canada?
c. What are patients and practitioners’ values and screening preferences regarding overweight and obesity prevention/treatment?
d. What process and outcome performance measures (indicators) have been identified in the literature to measure and monitor the impact of prevention/treatment for overweight and obesity?
CQ5. What are the most effective (accurate and reliable) risk assessment tools* identified in the literature to identify those at higher risk of obesity?
CQ6. What are the most effective (accurate and reliable) risk assessment tools* identified in the literature to assess future health risk as a result of obesity?
Is there direct evidence that primary care screening programs for adult obesity or overweight improve health outcomes or result in short-term (12 month) or sustained (>12 month) weight loss or improved physiological measures (i.e., glucose tolerance, blood pressure, and dyslipidemia)?
a. How well is weight loss maintained after a screening intervention is completed?
b. What is the most effective method of screening for overweight and obesity in adults in primary care?
c. What is the optimal interval/frequency for screening for overweight and obesity in adults in primary care?
d. What is the most effective type of screening (opportunistic vs. organized/systematic) for overweight and obesity in adults in primary care?
e. What are the harms associated with screening for overweight and obesity in adults in primary care (psychological distress, disordered eating, nutritional deficits, labeling, and cost burden)?
EMBASE, MEDLINE, Cochrane, CINAHL, PsycINFO, from 1980 to the present.
English and French.
Types of study to be included
Key question 1a-c, we will include randomized or controlled clinical trials evaluating the effectiveness of prevention interventions in adults, observational designs (prospective and retrospective cohorts, case-control studies, pre and post designs, all using a comparison group) and modelling studies. Case reports, case series, and chart reviews will be excluded.
Key Questions 1d-e, all study designs are permissible, including non-controlled observational designs.
Key question 2a-c restricting studies to RCTs for KQ2a-c and cohort and case-control studies in addition to RCT’s for KQ2d-e. All trials must include a true control group that received no intervention. More specifically, an acceptable control group couldn’t receive a personalized intervention, at-home workbook materials, and advice more frequently than annually, or participate in frequent weigh-ins (< 3 months). Providing a healthy lifestyle message was considered too similar to weight loss messages, and therefore would not be considered as a valid control group intervention.
Exclude: case reports, case series and chart reviews were excluded.
Exclude: studies with fewer than 30 participants per arm
Condition or domain being studied
Obesity is characterized by an increase in total body fat and is defined by a body mass index (BMI) >=30kg/m, based on the definition used by the World Health Organization and adopted by the Canadian Guidelines for Body Weight Classification in Adults. Adults (>=18 years) with BMI of 25kg/m to 29.9kg/m are considered overweight and at risk of becoming obese, whereas those with BMI of 18.5kg/m to 24.9kg/m are considered at low risk for morbidity.
Obesity has become a worldwide issue. According to the WHO report on global epidemic, an estimated one billion adults are overweight and at least 300 million are clinically obese. Obesity occurs in all age and ethnic groups, and is associated with socioeconomic status (SES).
This report will be used by the Canadian Task Force on Preventive Health Care to provide guidelines on the prevention of and screening for obesity in adults. The last Task Force guideline on the prevention of obesity was conducted in 2006 and published in 2007, while obesity screening was last examined in 1994. Since this time, other Canadian and international groups have provided guidance on obesity screening, management, and prevention, including the Obesity Canada Clinical Guidelines Expert Panel,(2006), the Scottish Intercollegiate Guidelines Network (2010), and the United States Preventive Services Task Force (2011). The lack of updated Canadian guidelines on this topic and the growing burden of obesity were key reasons for which this topic was chosen.
Adults (>= 18 years) who are normal weight or overweight/obese and must either be unselected, selected for low cardiovascular disease risk, or selected for increased risk for specified conditions (cardiovascular disease, hypertension, dyslipidemia, or type II diabetes)
Excluded: pregnant women, underweight or obese >=40 BMI
For key question 1, interventions focusing on weight gain prevention such as behaviorally-based interventions and complementary/alternative therapies will be included.
Exclude pharmacological interventions for normal weight populations and surgical interventions.
Key question 2 will include interventions focusing on weight loss, including behaviourally-based interventions, pharmacological (orlistat and metformin), or a combination of behavioral and pharmacological interventions
Exclude behavioral interventions that did not focus primarily on weight or that did not report weight-related outcomes, surgical interventions, primary prevention programs that did not involve a weight loss goal for all participants, and trials focusing on pharmacological agents other than orlistat or metformin
Exclude weight loss drugs not approved by Health Canada.
Q1 and 2 and Supplemental Question - No invention comparators (no active comparators)
Studies conducted in settings generalizable to Canadian primary care, (All countries listed as “high” human development on Human Development Index (over .90): Australia, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Hong Kong, Iceland, Ireland, Israel, Italy, Japan, Korea, Luxembourg, Netherlands, New Zealand, Norway, Portugal, Singapore, Slovenia, Spain, Sweden, Switzerland, United Kingdom and the United States), feasible for conducting in primary care, or feasible for referral from primary care
Exclude studies conducted in in-patient hospital settings, institutionalized settings, school-based programs, occupational settings, churches, and other settings deemed not generalizable to primary care, such as those with existing social networks among participants or the ability to offer intervention elements that could not be replicated in a health care setting, unless the intervention is primary care feasible
Key question 1a-c, health outcomes will include: cardiovascular disease, diabetes, musculoskeletal disorders, all cancers, overall and cause specific mortality, quality of life including psychological distress, BMI stabilization.
Key question 1d-e adverse effects will include: labeling, disordered eating, psychological distress, nutritional deficits and cost burden.
Key question 2 is restricted to outcomes as in the USPSTF review as we are updating their work. This includes restricting study interventions to:
multiple health outcomes: decreased morbidity from diabetes mellitus, cardiovascular disease, cancer, arthritis, asthma, and sleep apnea; improved depression; improved emotional function (scores on emotional subscales of quality of life instruments); physical fitness capacity or performance (not behavioral), physical functioning (scores on physical subscales of quality of life measures), disability (global measures of disability, such as activities of daily living); and mortality
Health outcomes include but not limited to morbidity (e.g. cardiovascular disease, type 2 diabetes, musculoskeletal disorders, all cancers, overall and cause specific mortality, quality of life including psychological distress and functioning), healthy BMI trajectory, improved behavioral measures (diet, activity level), and physiologic measures (e.g. glucose tolerance, fasting insulin and insulin resistance, blood pressure, lipid testing, and physical fitness). The evidence review will report on patient important outcomes if data is available and only for the tools that were identified in KQ4a and KQ4b. If there are insufficient comparative studies, then the ERSC will look at studies with single group who receive a risk assessment tool as the intervention with the outcome of sensitivity/specificity, PPV/NPV and AUROC.
Outcomes reported >= 12 months after the start of the intervention were included. Trials of treatment-related harms had no minimum follow-up requirement
Intermediate outcomes: include a reduction of weight or adiposity (a required outcome). Acceptable measures included weight, relative weight, total adiposity measures, or change in any of these measures
Other intermediate outcomes: include weight maintenance after an intervention has ended; and metabolic consequences (glucose tolerance, blood pressure, dyslipidemia)
Adverse outcomes: include serious treatment-related harms at any time point after an intervention began (i.e., death, medical issue requiring hospitalization or urgent medical treatment) or other treatment-related harms reported in trials
Outcomes reported with a minimum 12 months after the start of the intervention will be included. For harms and the risk assessment tools there is no time restriction.
Data extraction, (selection and coding)
To identify papers considered for Key Questions, titles and abstracts will reviewed in duplicate. Any article marked for inclusion by either reviewer will go for full text rating. Full text inclusion, quality assessment and data extraction will be done by two people. All discrepancies will be discussed and resolved; if consensus is not reached a third member of the research team will be the arbitrator. For Contextual Questions and grey literature, inclusion screening and abstraction will be done by one person.
Standard data extraction will include characteristics of included studies and all relevant outcome data.Data will be extracted only in studies where there is a weight-related outcome reported and report at baseline and post intervention data.
For the harms:
For the risk assessment tools we will be extracting patient important outcomes and PPV/NPV, sensitivity and specificity and AUROC scores.
Risk of bias (quality) assessment
Risk of bias will be assessed using the Cochrane Risk of Bias tool for RCTs and quasi-experimental designs and the Newcastle Ottawa Scale will assess risk of bias for cohort and case control studies. Overall strength of evidence will be assessed with GRADE.
Strategy for data synthesis
Where data are available we will be performing meta-analysis for all questions. If data are not sufficient, results will be reported using a narrative synthesis grouped by intervention and outcome for each key question.
Analysis of subgroups or subsets
For all KQs subgroup analyses by type of intervention would be performed (e.g. psychologically managed/supervised behavioural intervention and those that are not).
Subgroup analysis will be conducted for groups at high risk of obesity and related health issues.
The full review will be posted on the Canadian Task Force for Preventative Health Care website; a smaller version of the review will be submitted to publication and the Task Force has an active Knowledge Translation group who disseminate the new guidelines and supporting evidence
Contact details for further information
1280 Main St. W. DTC Room 321
Hamilton, Ontario, Canada L8S 4K1
Organisational affiliation of the review
Ms Donna Fitzpatrick-Lewis, McMaster University Dr Leslea Peirson, McMaster University Dr Donna Ciliska, McMaster University Ms Rachel Warren, McMaster University
Dr Paula Brauer, Canadian Task Force on Preventative Health Care and Guelph University
Anticipated or actual start date
05 September 2012
Anticipated completion date
29 March 2013
Canadian Institute of Health Research and the Public Health Agency of Canada
For question 2 we are updating Leblanc E, O’Connor E, Whitlock EP, Patnode C, Kapka, T. Screening and management of obesity and overweight in adults. Evidence Report No. XX. (Prepared by the Oregon Evidence-based Practice Center under Contract No. 290-02-0024, Task Order Number 2.) AHRQ Publication No. XX-XXX. Rockville, MD. Agency for Healthcare Research and Quality. May 2011.
Date of registration in PROSPERO
02 August 2012
Date of publication of this revision
07 March 2013
Stage of review at time of this submission
Piloting of the study selection process
Formal screening of search results against eligibility criteria
Risk of bias (quality) assessment
PROSPERO This information has been provided by the named contact for this review. CRD has accepted this information in good faith and registered the review in PROSPERO. CRD bears no responsibility or liability for the content of this registration record, any associated files or external websites.