A systematic review of inequalities in the uptake of, adherence to, and effectiveness of behavioral weight management interventions in adults.
Obesity reviews : an official journal of the International Association for the Study of Obesity 2022
Birch JM, Jones RA, Mueller J, McDonald MD, Richards R, Kelly MP, Griffin SJ, and Ahern AL
DOI : 10.1111/obr.13438
PubMed ID : 35243743
PMCID : PMC9285567
URL : https://onlinelibrary.wiley.com/doi/10.1111/obr.13438
The extent to which behavioral weight management interventions affect health inequalities is uncertain, as is whether trials of these interventions directly consider inequalities. We conducted a systematic review, synthesizing evidence on how different aspects of inequality impact uptake, adherence, and effectiveness in trials of behavioral weight management interventions. We included (cluster-) randomized controlled trials of primary care-applicable behavioral weight management interventions in adults with overweight or obesity published prior to March 2020. Data about trial uptake, intervention adherence, attrition, and weight change by PROGRESS-Plus criteria (place of residence, race/ethnicity, occupation, gender, religion, education, socioeconomic status, social capital, plus other discriminating factors) were extracted. Data were synthesized narratively and summarized in harvest plots. We identified 91 behavioral weight loss interventions and 12 behavioral weight loss maintenance interventions. Fifty-six of the 103 trials considered inequalities in relation to at least one of intervention or trial uptake (n = 15), intervention adherence (n = 15), trial attrition (n = 32), or weight outcome (n = 34). Most trials found no inequalities gradient. If a gradient was observed for trial uptake, intervention adherence, and trial attrition, those considered "more advantaged" did best. Alternative methods of data synthesis that enable data to be pooled and increase statistical power may enhance understanding of inequalities in behavioral weight management interventions.
Health inequalities are differences in health between different groups. Inequalities exist in who has overweight or obesity – those who live in a deprived area or have fewer years of education are more likely to have overweight or obesity.
The most common treatment for people with overweight and obesity are weight management interventions (such as WW or Slimming World). Weight management interventions help people with overweight or obesity to either lose weight or maintain previous weight loss.
We conducted a systematic review, which summarises all available research on a specific topic of interest, to find out whether health inequalities are present in weight management interventions, and if so, at what stage.
The first stage is uptake, which means attending at least one session.
The second stage is adherence, which takes into account how many intervention sessions a person actually attends versus how many sessions they were recommended to attend.
The final stage is the effectiveness of an intervention, which is the amount of weight lost at the end of the programme.
In our systematic review of trials of weight management interventions, we found that most studies of weight management interventions did not consider if the intervention worked as well in different groups. In the studies that did consider inequalities, there appeared to be a mixed impact.
For interventions that aimed to help people with overweight or obesity to lose weight, most studies did not find inequalities in intervention uptake, adherence or effectiveness. However, when a difference in intervention impact was observed at these stages, the intervention appeared to favour those we consider to be ‘more advantaged’ (such as those of a white ethnicity, better education or from a less deprived area). This suggests there is some evidence to suggest that these interventions may be widening inequalities in overweight and obesity.
Our findings were different for interventions that aimed for people to maintain previous weight loss. There were fewer of these studies (13, compared to 90 studies that looked at weight loss). It was only at the adherence stage we found any evidence of inequalities in these interventions.
Future research should use other methods, such as interviews, to better understand how we can prevent interventions for overweight and obesity from increasing health inequalities.