O
ur reviews found a large international evidence base, with the better-quality studies suggesting that individual-, community-, societal- and multilevel interventions that aim to prevent, reduce or manage obesity do not increase inequalities; that some universal interventions reduced the gradient in obesity;and that many targeted interventions are effective in decreasing obesity among lower-SES groups.
Implications for public health
Our review has found a large international evidence base but only limited effectiveness of interventions with the potential to reduce SES inequalities in obesity. The body of evidence in this review provides some support for the hypothesis that obesity management interventions in children and adults can be effective and that they do not increase health inequalities. Interventions that can be embedded into ongoing practice and operating systems need to be developed, rather than implementing interventions that are resource intensive and cannot be maintained long term. These reviews also highlight that, although we may now have a good sense of the range of interventions that are feasible for use in reducing the risk of obesity, we lack the knowledge of which specific intervention components are most effective in ensuring that the equity gradient is reduced. Being able to answer this question is of critical importance to decision-makers.
The reviews provide evidence of significant positive outcomes for the more disadvantaged. There was no evidence of a widening of health inequalities as a result of obesity management interventions. In addition, the relatively large number of studies of interventions targeting disadvantaged population groups provides useful information about the implementation strategies needed for obesity prevention efforts targeting these high-risk groups. We advocate for an assessment of outcomes by measures of equity, such as those indicated by PROGRESS, if a general population is targeted.
In relation to which interventions could be implemented by the UK public health community, the findings of this review are very limited to non-UK evidence and we cannot assume that such interventions will be effective outside their country context. It is also difficult to distinguish which specific components of intervention programmes are necessary to achieve the beneficial impacts on obesity in adults and children across all SES groups (our implementation tool found very little evidence of consistent factors behind successful interventions, for example in terms of empowerment/participation). However, our review has found tentative evidence of some interventions with the potential to reduce SES inequalities in obesity in children:
l School-based and environmental interventions targeted at low-SES children appear to have evidence of effectiveness– and over the longer term – in reducing obesity-related outcomes among low-income primary school-aged children. For example, the School Nutrition Policy Initiative (a 2-year multifaceted educational and environmental intervention in low-income schools in the USA) increased nutritional knowledge and the availability of healthy food and reduced the prevalence of overweight by 35%.109
l Multilevel interventions that use community empowerment mechanisms, for example, may also be effective in reducing the widening of inequalities in obesity among children. For example, the Australian Be Active Eat Well community capacity-building intervention was designed by a number of key organisations to build the community’s capacity to create its own solutions to promoting healthy eating, physical activity and healthy weight and was delivered universally in all intervention schools.
After 3 years, children in the intervention schools showed significantly lower increases in waist circumference and BMI.
The evidence reviewed here suggests that interventions of this type may therefore be worth commissioning in the UK by clinical commissioning groups or local authorities who wish to target services at low-income primary school children or children in deprived areas. However, these interventions may need to be piloted first and thoroughly evaluated using an experimental design.
Similarly, among adults, there is evidence that the following interventions targeted at individuals from low-income groups have some effectiveness– at least in the short term – in reducing SES inequalities in obesity, at least among low-income women, internationally and in the UK:
l Primary care-delivered tailored weight loss programmes– there is evidence from UK and US
studies132,134,135,149that monthly face-to-face lifestyle counselling on a healthy diet and physical activity behaviours, targeted at low-income women, can be effective in reducing body weight. For example, a UK study of a 12-week intervention found significant reductions in BMI, body weight and percentage body fat among overweight post-partum women living in areas of moderate to high deprivation.134
l Community-based weight loss interventions (diet clubs, commercial and behavioural programmes) have positive effects in the short term in low-SES groups or equally across the SES gradient.152,176,185,207
For example, a behavioural therapy (e.g. problem-solving, assertion, stimulus control) and social support (peer delivered in groups) intervention was effective at reducing weight among low-income men and women in the USA.185
These interventions may therefore be worth commissioning by clinical commissioning groups or local authorities who wish to target services at low-income women or at women in deprived areas. However, to be effective in the longer term, such interventions will need to be of a longer duration and supplemented with subsequent weight maintenance interventions. They may also need to be adapted to be effective among men.
Research recommendations
This review suggests that research and evaluation in this field would benefit from focusing on how to implement interventions effectively to scale, sustain the impacts over time and ensure equitable outcomes of interventions to manage childhood obesity. We recommend larger, longer-term studies, powered to detect the small changes that are likely to be found, with assessments of equity impacts, to enable translation of research findings into effective public health approaches for managing childhood obesity.
The nature of the evidence base has a number of implications for public health researchers. Most notably, although we found a very large international evidence base, the quality of the evidence found was largely observational and of moderate to low quality. This was particularly the case with the UK evidence base, which was surprisingly small and in methodological terms did not compare well with the US evidence base.
It is worth noting that, for the same type of intervention, observational studies are more likely to show positive effects than experimental studies. It is reasonable to suggest, therefore, that the most useful information on the way in which obesity (prevention or treatment) interventions impact on health inequalities is from moderate- to high-quality experimental studies of universal interventions. The large evidence base found resulted from the very inclusive nature of our search strategy and future research into the effects of interventions on health inequalities may wish to reflect on this– how far systematic reviewers search (in terms of databases and the study designs of included studies) is a difficult issue as there is a concern about missing potentially relevant studies, but there also needs to be a trade-off in terms of time, money and the quality of the studies found.
There were also very few studies of societal-level interventions, which might be expected to have more of an impact on the gradient in obesity.29This was particularly the case in terms of macro policy-level interventions, as the few studies that were found did not necessarily have obesity as their main outcome or indeed motivation behind the intervention (e.g. the US Food Stamp Program was not motivated by a desire
to reduce obesity). Similarly, the vast majority of interventions that were evaluated took a targeted approach to reducing SES inequalities in obesity, with only a minority of studies examining the effects of interventions across the SES gradient. The latter probably reflects a tendency among researchers, practitioners and funders to focus at this level when evaluating interventions as the evaluation of complex interventions is difficult and often gives equivocal results. Few studies were found that evaluated more upstream interventions; this is not evidence of a lack of effectiveness, rather a lack of evaluation evidence for this type of intervention. It is also the case that effectiveness was seldom sustainable over time. We did search for reports of observational studies of societal interventions that we are aware of, and which might have met our inclusion criteria, for example EPODE, Sure Start and Healthy Towns; however, we were unable to find any relevant evidence.
The majority of interventions that were included in the reviews took a targeted approach to tackling obesity and were concerned with weight loss interventions (‘treating’ existing obesity) rather than interventions that aim to prevent weight gain (‘preventing’ obesity). These ‘treatment’ interventions are more likely to show positive effects than‘prevention’ interventions.31The targeted approach also has limitations as even when interventions are effective among low-income groups they are only able to reduce the health inequalities gap and have little effect on the wider social gradient. Most of the child studies were school-based and aimed at primary school-aged children. The adult studies, especially the UK studies and the better-quality international studies, almost exclusively included women. The findings of effectiveness are therefore limited to women, given that weight loss is embedded in sociocultural contexts, including those relating to
gender.228We also found no studies that assessed the cost-effectiveness of interventions and meta-analysis could be conducted only on a minority of studies, given their heterogeneity.
Our results suggest a need for more evaluations of the effects of interventions on SES inequalities in child and adult obesity, particularly in terms of the following:
l priority 1– country context: the UK
l priority 2– population groups: adolescents and adult men
l priority 3– intervention types: macro-level interventions that potentially address the entire gradient (such as taxes on high-fat foods or a television advertising ban on fast foods) and multilevel interventions that, for example, use community empowerment mechanisms to reduce inequalities in obesity
l priority 4– study designs: experimental studies of effectiveness and cost-effectiveness.
There has been a real missed opportunity to evaluate the effects of such‘real-world’ interventions, and future interventions (such as Fulfilling Lives: a Better Start– see www.children-ne.org.uk/fulfilling-lives-better-start; accessed 16 September 2014) should include such analysis. There is therefore a need to review the possibility of conducting secondary analysis of existing intervention data sets (e.g. Healthy Towns, Change4Life– see www.nhs.uk/Change4Life/Pages/what-is-change-for-life.aspx; accessed 6 October 2014) to assess whether or not it is possible to retrospectively explore the effects of these UK interventions (that aim to manage obesity) on SES inequalities. We would also encourage all funders of such initiatives in the future to build a robust evaluation into such national programmes, or work alongside others who might conduct an evaluation (e.g. funded through the NIHR Public Health Research
programme). Research in this area is increasing rapidly in line with the increasing prevalence of obesity in developed countries and so regular updating of this review will be required.
Acknowledgements
W
e would like to thank the members of our project steering group for their time and advice throughout the review: Goof Buijs (Netherlands Institute for Health Promotion and Disease Prevention, Woerden, the Netherlands), Richard Cookson (University of York, UK), Liam Hughes (Local Government Improvement and Development, London, UK), Mike Kelly (University of Cambridge, UK), Louise Potvin (University of Montreal, Canada) and Martin White (Newcastle University, UK). We would also like to thank Jayne Kenworthy of the Wolfson Research Institute for Health and Wellbeing, Durham, UK, for her administrative support.This project was funded by the National Institute for Health Research Public Health Research programme (project number 09/3010/14).
Contributions of authors
Clare L Bambra (Professor, Public Health Policy) was responsible for overall co-ordination and project management. She provided methodological and conceptual input, analysis and synthesis input and, together with Frances C Hillier, led the drafting of the report and the preparation of the results for publication.
Frances C Hillier (Research Associate, Public Health Nutrition) was responsible for data collection, analysis and synthesis and, together with Clare L Bambra, led the drafting of the report and the preparation of the results for publication.
Joanne-Marie Cairns (Research Associate, Public Health Policy) contributed to data collection and analysis and the drafting of the report.
Adetayo Kasim (Statistician, Biomedicine) conducted the meta-analysis and contributed to the drafting of the report.
Helen J Moore (Lecturer, Public Health Nutrition) designed and conducted the searches and contributed to the data collection and the drafting of the report.
Carolyn D Summerbell (Professor, Public Health Nutrition) provided analysis and synthesis input and contributed to the drafting of the report.
Publications
Cairns JM, Bambra CL, Hillier-Brown FC, Moore HJ, Summerbell CD. Weighing up the evidence: a systematic review of the effectiveness of workplace interventions to tackle socio-economic inequalities in obesity [published online ahead of print 14 October 2014]. J Public Health 2014. doi: 10.1093/pubmed/fdu077 Hillier-Brown FC, Bambra CL, Cairns JM, Kasim A, Moore HJ, Summerbell CD. A systematic review of the effectiveness of individual, community and societal level interventions at reducing socioeconomic inequalities in obesity amongst adults [published online ahead of print 12 May 2014]. Int J Obes (Lond) 2014. doi:10.1038/ijo.2014.75.
Hillier-Brown FC, Bambra CL, Cairns JM, Kasim A, Moore HJ, Summerbell CD. A systematic review of the effectiveness of individual, community and societal level interventions at reducing socioeconomic
References
1. World Health Organization. Obesity: Preventing and Managing a Global Epidemic: Report of a WHO Consultation of Obesity. WHO technical report series 894. Geneva: World Health Organization; 2000.
2. Rokholm B, Baker JL, Sørensen TIA. The levelling off of the obesity epidemic since the year 1999– a review of evidence and perspectives. Obes Rev 2010;11:835–46.http://dx.doi.org/
10.1111/j.1467-789X.2010.00810.x
3. Olds T, Maher C, Zumin S, Péneau S, Lioret S, Castetbon K, et al. Evidence that the prevalence of childhood overweight is plateauing: data from nine countries. Int J Pediatr Obes 2011;6:342–60.
http://dx.doi.org/10.3109/17477166.2011.605895
4. Butland B, Jebb S, Kopelman P, McPherson K, Thomas S, Mardell J, et al. Tackling Obesities:
Future Choices– Project Report. London: Government Office for Science; 2007.
5. Friel S, Chopra M, Satcher D. Unequal weight: equity oriented policy responses to the global obesity epidemic. BMJ 2007;335:1241–3.http://dx.doi.org/10.1136/bmj.39377.622882.47 6. Robertson A, Lobstein T, Knai C. Obesity and Socio-economic Groups in Europe: Evidence Review
and Implications for Action. Report to the European Commission. 2007. URL:http://ec.europa.eu/
health/ph_determinants/life_style/nutrition/documents/ev20081028_rep_en.pdf (accessed 16 September 2014).
7. Organisation for Economic Co-operation and Development. Obesity and the Economics of Prevention: Fit not Fat. OECD Publishing; 2010. URL: www.oecd-ilibrary.org/social-issues-migration-health/obesity-and-the-economics-of-prevention_9789264084865-en (accessed 16 September 2014).
8. Cross-Government Obesity Unit, Department of Health, Department of Children, Schools and Families. Healthy Weight, Healthy Lives: A Cross-Government Strategy for England. London:
The Stationery Office; 2008.
9. Reilly JJ, Methven E, McDowell ZC, Hacking B, Alexander D, Stewart L, et al. Health consequences of obesity. Arch Dis Child 2003;88:748–52.http://dx.doi.org/10.1136/adc.88.9.748
10. White M, Adamson A, Chadwick T, Dezateux C, Griffiths L, Howel D, et al. The Changing Social Patterning of Obesity: an Analysis to Inform Practice and Policy Development. Final Report to the Policy Research Programme. London: Department of Health; 2007.
11. Law C, Power C, Graham H, Merrick D. Obesity and health inequalities. Obes Rev 2007;8:19–22.
http://dx.doi.org/10.1111/j.1467-789X.2007.00312.x
12. Shrewsbury V, Wardle J. Socioeconomic Status and adiposity in childhood: a systematic review of cross-sectional studies 1990–2005. Obesity 2008;16:275–84.http://dx.doi.org/10.1038/
oby.2007.35
13. El-Sayed A, Scarborough P, Galea S. Socioeconomic inequalities in childhood obesity in the United Kingdom: a systematic review of the literature. Obes Facts 2012;5:671–92.http://dx.doi.org/
10.1159/000343611
14. El-Sayed A, Scarborough P, Galea S. Unevenly distributed: a systematic review of the health literature about socioeconomic inequalities in adult obesity in the United Kingdom. BMC Public Health 2012;12:18.http://dx.doi.org/10.1186/1471-2458-12-18
15. Health and Social Care Information Centre. Health Survey for England– 2011: Volume 1 – Health,
16. Health and Social Care Information Centre. National Child Measurement Programme: England, 2011/12 School Year. London: Department of Health; 2012.
17. Howe LD, Tilling K, Galobardes B, Smith GD, Ness AR, Lawlor DA. Socioeconomic disparities in trajectories of adiposity across childhood. Int J Pediatr Obes 2011;6:e144–53.http://dx.doi.org/
10.3109/17477166.2010.500387
18. Giskes K, Avendano M, Brug J, Kunst AE. A systematic review of studies on socioeconomic inequalities in dietary intakes associated with weight gain and overweight/obesity conducted among European adults. Obes Rev 2010;11:413–29.http://dx.doi.org/10.1111/j.1467-789X.2009.
00658.x
19. Bambra C, Joyce KE, Maryon-Davies A. Priority Health Conditions– Task Group 8 Report to the Strategic Review of Health Inequalities in England Post-2010 (Marmot Review). London:
University College London; 2009.
20. Bambra C, Joyce K, Bellis M, Greatley A, Greengross S, Hughes S, et al. Reducing health inequalities in priority public health conditions: using rapid review to develop proposals for evidence-based policy. J Public Health (Oxf) 2010;32:496–505.http://dx.doi.org/10.1093/
pubmed/fdq028
21. Woodman J, Lorenc T, Harden A, Oakley A. Social and Environmental Interventions to Reduce Childhood Obesity: a Systematic Map of Reviews. EPPI-Centre report no. 16102008.
London: EPPI-Centre; 2008.
22. World Health Organization Commission on the Social Determinants of Health. Closing the Gap in a Generation: Health Equity through Action on the Social Determinants of Health. Final Report of the Commission on Social Determinants of Health. Geneva: World Health Organization; 2008.
23. Egan M, Bambra C, Petticrew M, Whitehead M. Reviewing evidence on complex social interventions: appraising implementation in systematic reviews of the health effects of organisational-level workplace interventions. J Epidemiol Community Health 2009;63:4–11.
http://dx.doi.org/10.1136/jech.2007.071233
24. Chow CK, Lock K, Teo K, Subramanian S, McKee M, Yusuf S. Environmental and societal influences acting on cardiovascular risk factors and disease at a population level: a review.
Int J Epidemiol 2009;38:1580–94.http://dx.doi.org/10.1093/ije/dyn258
25. Whitehead M. A typology of actions to tackle social inequalities in health. J Epidemiol Community Health 2007;61:473–8.http://dx.doi.org/10.1136/jech.2005.037242
26. Graham H, Kelly M. Health Inequalities: Concepts, Frameworks and Policy. London: Health Development Agency; 2004.
27. Centre for Reviews and Dissemination. Undertaking Systematic Reviews of Research on Effectiveness. CRD’s Guidance for Carrying Out or Commissioning Reviews, 2nd edn.
York: Centre for Reviews and Dissemination, University of York; 2001.
28. Higgins J, Green S, editors. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011). The Cochrane Collaboration; 2011.
29. Bambra C, Hillier F, Moore H, Summerbell C. Tackling inequalities in obesity: a protocol for a systematic review of the effectiveness of public health interventions at reducing socioeconomic inequalities in obesity amongst children. Syst Rev 2012;1:16.http://dx.doi.org/10.1186/
2046-4053-1-16
30. Shaw K, Gennat H, O’Rourke P, Del Mar C. Exercise for overweight or obesity. Cochrane Database Syst Rev 2006;4:CD003817.
31. Waters E, de Silva-Sanigorski A, Hall B, Brown T, Campbell K, Gao Y, et al. Interventions for preventing obesity in children. Cochrane Database Syst Rev 2011;12:CD001871.http://dx.doi.org/
10.1002/14651858.CD001871.pub3
32. Bambra C, Egan M, Thomas S, Petticrew M, Whitehead M. The psychosocial and health effects of workplace reorganisation. 2. A systematic review of task restructuring interventions. J Epidemiol Community Health 2007;61:1028–37.http://dx.doi.org/10.1136/jech.2006.054999
33. Bambra C, Whitehead M, Sowden A, Akers J, Petticrew M.’A hard day’s night?’ The effects of Compressed Working Week interventions on the health and work-life balance of shift workers:
a systematic review. J Epidemiol Community Health 2008;62:764–77.http://dx.doi.org/10.1136/
jech.2007.067249
34. Bambra CL, Whitehead MM, Sowden AJ, Akers J, Petticrew MP. Shifting schedules: the health effects of reorganizing shift work. Am J Prev Med 2008;34:427–34.http://dx.doi.org/10.1016/
j.amepre.2007.12.023
35. Deeks J, Dinnes J, D’Amico R, Sowden A, Sakarovitch C, Song F, et al. Evaluating non-randomised intervention studies. Health Technol Assess 2003;7(27).http://dx.doi.org/10.3310/hta7270 36. Egan M, Bambra C, Thomas S, Petticrew M, Whitehead M, Thomson H. The psychosocial and
health effects of workplace reorganisation. 1. a systematic review of interventions that aim to increase employee participation or control. J Epidemiol Community Health 2007;61:945–54.
http://dx.doi.org/10.1136/jech.2006.054965
37. Joyce K, Pabayo R, Critchley J, Bambra C. Flexible working conditions and their effects on employee health and wellbeing. Cochrane Database Syst Rev 2010;2:CD008009.http://dx.doi.org/10.1002/
14651858.CD008009.pub2.
38. Effective Public Health Practice Project. Effective Public Health Practice Project Quality Assessment Tool for Quantitative Studies. 2009. URL:www.ephpp.ca/tools.html(accessed 1 September 2011).
39. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA, et al. The PRISMA
39. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA, et al. The PRISMA