Weight loss in adults following bariatric surgery, a systematic review of preoperative behavioural predictors

Abstract

Summary Bariatric surgery is effective in treating obesity in many cases, yet as many as 50% of patients may not achieve the desired weight reduction. Preoperative modifiable behavioural factors could help patient selection and intervention design to improve outcomes. Medline, EMBASE, Cochrane Library and PsychINFO were searched to identify studies published between 1 January 2008 and 14 February 2019 reporting on preoperative modifiable behavioural factors associated with postoperative weight loss, with minimum 2 years follow‐up. A total of 6888 articles were screened, 34 met the inclusion criteria. Maladaptive eating behaviours (MEB), preoperative weight loss (PWL), and tobacco use were reported 21, 18, and 3 times respectively. Physical activity and substance abuse were each reported once. Most articles on PWL (72.2%) and MEB (52.4%) reported no association. Positive associations were reported in 22.2% and 14.3% of articles for PWL and MEB respectively. Negative associations were reported in 5.6% and 33.3% of articles for PWL and MEB, respectively. Marked heterogeneity in outcome reporting hindered quantitative synthesis. The current paucity of evidence amenable to synthesis leads to ongoing uncertainty regarding the size and direction of association between PWL and MEB with outcomes following bariatric surgery. Long‐term studies with common reporting of outcomes are needed.

Frequency of Short- vs Long-Term Reporting of Bariatric Surgery Outcomes

“…Publication bias has been raised as a possibility surrounding the lack of studies reporting long-term outcomes [19]. Short-term studies tend to over-inflate weight loss while masking the factors discussed above that would otherwise be exposed with longer follow-up duration.…”

“…The heterogeneous nature of postoperative outcomes reported in bariatric surgery has already been raised. Inconsistent definitions of both follow-up intervals and weight loss outcomes greatly hinders data synthesis and analysis [19]. In 2015, the American Society of Metabolic and Bariatric Surgery (ASMBS) highlighted this and outlined clear reporting guidelines to address the need for standardisation of reporting bariatric surgery follow-up intervals and outcomes [20].…”

Reporting of weight loss outcomes in bariatric surgery following introduction of 2015 ASMBS guidelines

“…Heterogeneity in reporting weight loss outcomes stands as a barrier to this -an issue which has been highlighted by the American Society for Metabolic and Bariatric Surgery (ASMBS) (3) , the BARIACT Project (4) and systematic reviews which highlight difficulties around synthesizing heterogeneous data (5,6) .…”

“…Using these weight loss outcomes collectively, as outlined by the ASMBS guidance, is more favorable than reporting a single outcome on its own. It provides a more robust evidence base and maximizes the chances of multiple publications containing comparable outcome measures that can be combined into a meta-analysis (6) . Furthermore, it also reduces the chances of authors using novel outcome measures which can inadvertently amplify the magnitude and significance of results (7) .…”

Psychological functioning and well‐being before and after bariatric surgery; what is the benefit of being self‐compassionate?

“…Long-term surgical results are determined not only by surgical and medical somatic factors (such as type of operation and number of medical conditions) but also by psychosocial factors such as personality and motivation (Hsu et al, 1998;Nielsen et al, 2020;van Wezenbeek, van Hout, & Nienhuijs, 2016). Greater post-operative weight loss has previously been associated with younger age, lower initial body mass index (BMI), greater pre-operative weight loss, lack of severe psychopathological conditions such as depression and anxiety, and lack of personality disorders (Agüera et al, 2015;Kourounis, Kong, Logue, & Gibson, 2020;Livhits et al, 2012). However, previous research findings regarding the predictive value of psychosocial factors remain inconclusive and sometimes are even contradictory due to methodological and conceptual inconsistencies such as using different outcome measures, varying definitions of predictor variables, small sample sizes and diverse lengths of follow-up (Bastos et al, 2013;Livhits et al, 2012;Maciejewski et al, 2016;van Hout, Verschure, & Van Heck, 2005;van Wezenbeek et al, 2016).…”