Behavioural interventions for severe obesity before and/or after bariatric surgery: a
systematic review and meta-analysis
Fiona Stewart MA MSc MSc, Alison Avenell BSc MSc MBBS MD FRCP (Edinburgh) FRCPath
Health Services Research Unit, University of Aberdeen, UK.
Keywords
Severe obesity, bariatric surgery, complex interventions, lifestyle management, behaviour change,
weight loss
Running title
Behavioural interventions and surgery
Acknowledgements
We would like to thank the following study authors for providing additional data and clarifications:
Alison Fielding, Haldis Lier, Monica Nijamkin, Jane Ogden, Anastasios Papalazarou, Manish Parikh,
Brian Swenson, Andresa Triffoni, Jean Michel Oppert, Marie-France Langlois, David Sarwer and
Dale Bond. We also thank Dr. Kevin Deans and the staff at the bariatric surgery clinic at Aberdeen
Royal Infirmary. The Health Services Research Unit, University of Aberdeen, is funded by the Chief
Scientist Office of the Scottish Government Health Directorates. The views expressed are those of the
authors.
Corresponding author
Fiona Stewart [email protected]
Health Sciences Building
Foresterhill
University of Aberdeen
Aberdeen AB25 2ZD
United Kingdom
1
Abstract
Background: Significant, sustained weight loss through conventional, non-surgical interventions is
often unattainable for people with severe obesity (e.g. BMI ≥ 40kg/m2 or ≥ 35kg/m2 with comorbidities). Bariatric surgery is effective in treating severe obesity but surgery alone without
additional behaviour change management may not result in optimum long-term weight loss and
maintenance. This systematic review and meta-analysis of randomised controlled trials evaluated the
effectiveness of lifestyle interventions before and/or after bariatric surgery.
Methods: MEDLINE, Embase, Cochrane Central Register of Controlled Trials and clinical trials
registers were searched for eligible studies. Key journals were handsearched. Last search date
December 2014. Eligible interventions had the explicit aim of changing behaviour related to diet
and/or physical activity, starting within twelve months of surgery, either pre- or post-operatively, and
with at least six months’ follow-up. The primary outcome was weight change; secondary outcomes
included surgical complications, quality of life and changes in co-morbidities. Random effect metaanalyses were undertaken. Study quality was assessed with the Cochrane Collaboration’s risk of bias
tool.
Results: Eleven trials met the inclusion criteria. Behavioural interventions appear to improve weight
loss at 12 months after bariatric surgery.. Secondary outcome data were lacking and weight outcomes
were reported inconsistently. Overall, the methodological quality of the identified trials was low.
Conclusion: The strength of evidence is limited by the relatively small number of trials identified and
by their low methodological quality and short follow-up duration. Well-designed RCTs with longterm follow-up are required.
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Introduction
Systematic reviews comparing bariatric surgery (BS) to non-surgical obesity treatment have
consistently found surgery to result in significantly greater weight loss and substantial improvements
in co-morbidities [1-3]. Evidence from a systematic review and meta-analysis [3] has shown a
clinically significant difference in weight loss between surgical and non-surgical treatments (-26kg
[95% CI -21 to -31]). Additionally, type 2 diabetes remission was five times more likely in surgical
patients than in those treated non-surgically (relative risk 5.3 95% CI 1.8 to 15.8) [3].
However, weight regain and diabetes relapse following surgery are common. Evidence from longterm observational studies suggests that the majority of surgical patients begin to regain weight two
years after surgery, with some experiencing weight regain at just six months post-operatively [4]. One
study showed 7% mean weight regain at six years after surgery compared to two years post-surgery
[5]. Another showed 25% mean weight regain at ten years compared to one year after surgery [6] in
addition to a significant degree of diabetes relapse (72% in remission at two years post-operatively but
only 30% still in remission after 15 years) [7]. The reasons for suboptimal weight maintenance
include disordered eating behaviours and poor adherence to post-surgery dietary advice [8].
Additional support in the form of behavioural interventions for BS patients is recommended by some
national clinical guideline bodies. These interventions typically comprise one or more components
relating to diet, physical activity and/or behaviour change therapy. In the UK, the National Institute
for Health and Care Excellence (NICE) and Scottish Intercollegiate Guidelines Network (SIGN)
recommend at least two years of post-operative support to optimise behaviour change in terms of diet
and physical activity [9, 10]. Australian guidance highlights the need for additional lifestyle
management support and recommends that long-term post-operative behaviour change strategies are
an integral part of surgical treatment for obesity [11]. However, none of these guidelines advises any
specific intervention that is known to be clinically effective. US guidelines acknowledge that post-
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operative weight regain is common but offer no recommendations regarding lifestyle interventions in
addition to surgery to prevent weight regain [12].
It is unclear whether pre- or post-operative behavioural interventions, or both, would be appropriate to
improve weight loss and other clinical outcomes. Weight loss immediately before surgery is often
encouraged to reduce liver mass and therefore minimise the risk of surgical complications [13] but
longer-term pre-operative interventions could be beneficial in establishing effective behaviours to
improve weight loss and other outcomes after surgery. Post-operative interventions are clearly
intended to optimise and maintain surgically-induced weight loss.
The existing systematic review evidence, which indicates that pre-operative [14] and post-operative
weight loss interventions [15-17] are associated with improved weight loss outcomes, is based largely
on observational studies, whose findings may not be as reliable as those from randomised controlled
trials (RCTs). To the best of our knowledge, no systematic reviews of RCTs have been published
examining both pre-operative and post-operative lifestyle interventions.
The aim of this systematic review and meta-analysis of RCTs was to investigate the effectiveness of
behavioural interventions before and/or after BS in improving weight loss and other outcomes for
people with severe obesity.
Methods
A protocol outlining the aims, objectives and proposed methods of the review was developed a priori
and is available from the authors on request.
Evidence identification
Highly sensitive electronic searches were carried out to identify RCTs of behavioural interventions for
patients undergoing BS. The search strategies are available from the authors. The databases searched
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were: Ovid MEDLINE (1946 to November week 3 2014), Ovid MEDLINE-in-Process and Other
Non-Indexed Citations (31st December 2014), Ovid Embase (1974 to 2014 December 30), EBSCO
CINAHL (1981 to December 2014), Ovid PsycINFO (1806 to December 2014), Scopus In Press
(January 2015) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue
12, December 2014). Clinical trials registers were searched and investigators of relevant ongoing
studies were contacted for further data. Reference lists in relevant articles were scrutinised to identify
further reports and relevant journals were handsearched. The literature search was restricted to studies
published since 1990 because the concomitant behavioural programmes studied before this date are
unlikely to be relevant to current practice. No language limitations were imposed. Authors of eligible
published studies were contacted to request additional data or to seek clarification where information
in the published report was lacking or ambiguous.
Eligibility criteria
Eligible trials had to be RCTs or quasi-RCTs, open only to adults (age ≥ 18 years or any given
definition of adult) with BMI ≥ 35kg/m2 with significant co-morbidities or BMI ≥ 40kg/m2,
undergoing any kind of BS. Any behavioural interventions were eligible, with the explicit aim of
changing behaviour related to diet and/or physical activity, starting within 12 months of surgery,
either pre- or post-operatively. A minimum of six months’ follow-up was specified.
Eligible comparators were usual or standard care, waiting list control or no intervention. Eligible
studies had to report the primary outcome of weight change, e.g. weight, excess weight loss or BMI.
Secondary outcomes of interest were: changes in associated co-morbidity status, e.g. type 2 diabetes,
metabolic syndrome, hypertension; surgical complications; quality of life (QoL); cost-effectiveness
outcomes; objectively measured lifestyle changes e.g. physical activity. Exclusion criteria were
pharmacological interventions, complementary therapies, and conference abstracts without full text
publications.
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Data collection, extraction and analysis
Search results were screened by one reviewer (FS), with a 10% random sample of titles and abstracts
double screened by the second reviewer (AA). All studies selected for full text assessment were
screened by both reviewers (FS and AA). Any disagreements were resolved by consensus. A data
extraction form was developed a priori. One reviewer (FS) carried out data extraction for all included
studies, checked by the second reviewer (AA).
Risk of bias of each included study was assessed independently by the two reviewers using the
Cochrane Collaboration’s risk of bias tool [18].
Data were imported into Review Manager 5 (The Cochrane Collaboration, Oxford) for quantitative
synthesis. Where sufficient data were available, studies reporting outcomes at 12 months after surgery
were combined in meta-analyses; for outcomes at 24 months further meta-analyses were undertaken.
Due to the inevitable heterogeneity in lifestyle interventions random-effect meta-analyses were
undertaken. Means or changes in means between groups were reported. Missing data were requested
from study authors; where authors did not respond, data were estimated by the following methods:
where possible, missing weight data were calculated from reported height and BMI and where
standard deviations (SDs) were not reported, the largest reported SD amongst the included studies was
used for that comparison, which ensured the most conservative estimate of effect was calculated.
Meta-analyses with and without estimated standard deviations were compared to assess the effect of
using estimated data.
Statistical heterogeneity was investigated by visual inspection of forest plots, the Q-test (where p <
0.1 implies statistical heterogeneity) and by examining the I2 statistic, where a result of greater than
50% indicates the presence of substantial statistical heterogeneity [19]. Clinical and methodological
heterogeneity were considered by examining differences between studies in terms of study design,
outcomes measured, interventions delivered and inclusion criteria for participants.
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Sensitivity analyses were planned to compare studies judged to be at low risk of bias for allocation
concealment and randomisation with those judged to be at higher risk of bias. However, insufficient
methodological details were reported in the included studies to be able to carry this out.
Results
The literature search identified 2491 reports of studies, of which 92 were selected for full text
screening. Eleven primary studies (15 reports) met the eligibility criteria and eight were included in
meta-analyses (figure 1). Contact with study authors yielded additional unpublished data from two
studies [20, 21] and points of clarification relating to seven of the included studies [20-27].
Characteristics of included studies
The included studies incorporated data from 916 participants, of whom 726 (79%) were female.
Seven studies (63%) took place in the USA; the others were in Europe or Australia. The
characteristics of the included studies are summarised in Table 1. Interventions targeted changes to
diet [20-28] or physical activity [29] or behaviour change counselling [21, 23, 25, 28]. Most of the
trials included input from dietitians [20, 22, 24-26], with some trials involving psychotherapists [21,
23, 28]. Four ongoing trials of physical activity interventions were also identified (one pre-operative
[30] and three post-operative [31-33]). Solomon and colleagues’ study [34] did not include any
specific intervention; participants were simply required to lose ≥ 10% excess weight pre-operatively.
Parikh and colleagues’ study [25] was the only one to randomise participants to more than two groups
(one for group delivery of the intervention, another for individual delivery and a control group).
However, the results were not reported separately for the two intervention arms.
The studies by Parikh [25] and Coen [29] followed up participants for six months only and were not
included in meta-analyses because longer term data from other studies allowed for more informative
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data synthesis to be undertaken. The trial by Papalazarou and colleagues [24] was the only study to
follow up participants for 36 months.[26].
Risk of bias
Figure 2 summarises the risk of bias assessment for all included studies. Insufficient reporting detail
resulted in an ‘unclear’ judgement of risk of bias in most domains.
One study [20] was judged to be at high risk of bias for random sequence generation and allocation
concealment due to the investigators’ use of alternate allocation. Two studies [21, 23] were judged to
be at low risk of bias for allocation concealment. One study clearly reported blinding of outcome
assessors [29]. Risk of attrition bias was high in one study [20] because of the authors’ suggestion that
withdrawal from the intervention arm was partly due to unacceptability of the intervention [20]. Two
studies [23, 25] were judged to be at high risk of bias for selective outcome reporting, due to
deviations from pre-specified analysis of outcomes.
Primary outcome: weight
A range of outcomes relating to weight and weight change was reported: weight [20, 22-24, 28, 29,
34], BMI [22, 25, 27-29, 34], excess weight loss (EWL) [22], %EWL [22, 24, 25, 27, 28, 34], waist
circumference [29] and % ideal body weight [28]. With no single outcome reported in all studies it
was not possible to combine all studies in one single meta-analysis.
Time after surgery: 6 months
Coen and colleagues’ [29] physical activity intervention did not demonstrate significant differences in
weight, BMI or waist circumference between exercisers and controls at six months after surgery. At
the same time point, Parikh’s pre-operative medically-supervised weight management intervention
[25] found no significant difference in BMI change (control group -4.35kg/m2 [SD 2.06] versus
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intervention group -5.27kg/m2 [SD 2.73], reported p = 0.31) but those in the intervention arm
achieved greater %EWL than controls (15.9% versus 14.0%, reported p < 0.05).
Time after surgery: 12 months
Weight
Body weight data from five post-operative intervention studies were available to be pooled (figure 3)
[20, 22-24, 28] (mean difference -4.55kg [95% CI -13.08 to 3.99, p = 0.3]). Heterogeneity was high
(I2 = 71%). All five trials investigated dietary counselling, with or without physical activity
counselling and behaviour change therapy.
The same meta-analysis with two additional pre-operative studies (Lier [21] and Solomon [34] (with
estimated SDs) showed the same direction of effect but still did not reach statistical significance
(mean difference -4.97 [95%CI -11.37 to 1.43, p = 0.13]). Heterogeneity remained high (I2 = 57%).
The two additional studies investigated counselling (cognitive behaviour therapy) [21] or required
participants to achieve ≤ 10% EWL by any means of their choice [34]. When the data from the two
pre-operative interventions were pooled, with estimated SDs, they showed a mean difference of 5.20kg (95% CI -15.05 to 4.65, p = 0.3).There was insufficient evidence to demonstrate any
difference between pre- and post-operative interventions.
Percent excess weight change
Percent excess weight change (%EWC) data from four post-operative studies were pooled [22, 24, 27,
28] (figure 4). Two were diet-based (high protein diets) [22, 27], while the other two [24, 28] were
based on dietary, physical activity and behaviour change therapy. Percent EWC was greater in the
intervention groups than in controls (mean difference -10.85% [95% CI -19.02 to -2.69, p = 0.009]).
Heterogeneity was high (I2 = 65%) although the direction of effect was largely similar across the
studies. The addition of Solomon’s pre-operative study [34], using a conservatively estimated SD,
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reduced the summary estimate marginally (-10.26% [95% CI -16.97 to -3.56, p = 0.003]).
Heterogeneity remained high (I2 = 59%).
Weight change
Figure 5 shows the difference in mean weight change between the intervention and control groups at
12 months after surgery. Overall, the interventions showed a mean difference of -4.40kg (95% CI 7.10 to -1.69, p = 0.001). There was no statistically significant difference between pre-operative [21,
34] and post-operative [20, 22-24, 26, 28] interventions. The same meta-analysis with the addition of
Dodsworth’s study [20], with an estimated SD, showed a slightly smaller mean difference in favour of
the intervention of -4.04kg (95% CI -6.75 to -1.32, p = 0.004).
BMI
Data from two post-operative studies were pooled (figure 6); Nijamkin’s dietary support intervention
[22] and Tucker’s study of diet, physical activity and behaviour change counselling [28]. Participants
receiving an intervention achieved lower BMIs than controls at 12 months after surgery (mean
difference -2.77 kg/m2 [95% CI -6.25 to 0.72, p = 0.12]) but the difference was not statistically
significant.
Using conservatively estimated SDs for Solomon’s [34] and Swenson’s [27] studies produced a
smaller mean difference in BMI of -1.52kg/m2 (95% CI -4.31 to 1.28, p = 0.29), with a high degree of
heterogeneity (I2 = 51%).
Time after surgery: 24 months
Weight
Weight data from two post-operative studies were pooled (figure 7), both of which investigated
dietary, physical activity and behaviour change therapy [24, 28]. There was no significant difference
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in weight between participants undergoing interventions, and controls at 24 months after surgery
(mean difference -7.14kg [95% CI -32.42 to 18.13, p = 0.58]). Heterogeneity was high (I2 = 79%) and
the direction of effect varied substantially across the studies.
Weight change and %EWC
Weight change data (figure 8) and %EWC data (figure 9) from the same two post-operative studies
[24, 28] were pooled. Weight change was significantly greater for participants receiving an
intervention than controls (mean difference -12.96kg [95% CI -21.66 to -4.26, p = 0.03]). The
direction of effect was strongly in favour of the intervention. Statistical heterogeneity was low (I2 =
0%). Data relating to %EWC did not reach statistical significance (mean difference -13.97%EWC
[95% CI -30.53 to 2.58, p = 0.1]) and heterogeneity was high (I2 = 68%).
Time after surgery: 36 months
The only study to measure outcomes at 36 months post-operatively reported significantly lower mean
weight in the intervention group (84.2kg [SD 3.3] compared to 102.5kg [SD 3.5], reported p < 0.001)
as well as significantly greater %EWC in the intervention group (-74.8% [SD 3.8] compared to 49.1% [SD 3.8], reported p < 0.05) with no reported withdrawals from the study [24].
Secondary outcomes
Only two studies reported any of the pre-specified secondary outcomes at six months’ follow-up or
longer. Solomon and colleagues’ pre-operative study reported non-statistically significant differences
in mean co-morbidities per participant at 12 months (0.3 in the intervention group and 0.7 in the
control group) [34] and in surgical complication rates (six in the intervention group and five in the
control group) [35]. At 24 months’ follow-up, Sarwer and colleagues’ post-operative diet-based study
[26] reported 20% (8/41) of participants in the intervention group versus 26% (11/43) of controls
experienced vomiting/dumping and 10% (4/41) in the intervention group versus 5% (2/43) of controls
experienced nausea. The authors reported that the data were insufficient to enable statistical testing.
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Attrition
Where participant withdrawal was reported, some studies experienced high rates of attrition in all
arms. One study [29] offered financial incentives to all participants for completing baseline and final
assessments and achieved a high completion rate, although withdrawal was slightly higher in the
intervention group (6/66) than in the control group (3/62). Studies with smaller sample sizes were
more likely to have high attrition, with one notable exception which reported no dropouts even after
three years [24]. Aside from this outlier, the median proportion of participants completing the trials
was 63% (range 38%-94%).[26]
Discussion
Additional pre- or post-operative support for BS patients appears to improve post-operative weight
loss according to some methods of reporting weight outcomes, but the current evidence from RCTs is
too limited to be confident about the true extent of the effectiveness of lifestyle interventions.
The findings of the single physical activity study that met our inclusion criteria concur with other
comparative studies of post-operative physical activity interventions, where participants taking part in
physical activity interventions have not lost more weight than controls [36-38]. However, some
significant improvements were reported in waist circumference and fat mass [37] and in quality of life
[38]. Nevertheless, Egberts and colleagues’ [39] systematic review found that physical activity was
associated with greater weight loss in BS patients but this was based solely on observational studies
because RCT evidence was lacking. The impact of physical activity and exercise on clinical outcomes
and quality of life in BS patients remains unclear.
In the UK, recent NICE guidelines [9] have identified post-operative behavioural interventions as a
research priority to assess their effectiveness in improving weight loss and weight maintenance. The
guidance recommends at least two years of post-operative psychological support and advice relating
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to diet and physical activity but this is based on limited evidence from two RCTs [24, 40, 41], one of
which did not meet our inclusion criteria because the intervention took place at least three years postoperatively. This six month intervention, targeted at patients who had lost less than 50% excess
weight, comprised dietary advice, a prescribed exercise programme and telephone counselling. The
intervention group lost more weight than controls in both absolute terms and in %EWC (-3.6kg [SD
9.6] versus -0.6kg [SD 6.7] and -5.8%EWC [SD 3.5] versus -0.9%EWC [SD 3.2]) and compliance
with the counselling element was relatively high, while adherence to the dietary and physical activity
advice was not reported. The results of this trial, taking place at three years after surgery, suggest that
benefits can be derived beyond the two year period stipulated in the NICE guidance [9].
Furthermore, our results showing -10.9%EWC and -14%EWC at 12 and 24 months after surgery
respectively agree with Magro and colleagues’ findings that post-operative weight nadir may not
always be achieved until after the first year following surgery [42] therefore follow-up care beyond
two years is likely to be helpful. Kalarchian and colleagues [41] suggest one year after surgery could
be the optimal time to initiate lifestyle interventions, when patients have adjusted to the physiological
changes associated with bariatric surgery and may be more ready to incorporate lifestyle changes into
their behaviour.
It was hypothesised by the three pre-operative RCTs [21, 25, 34] included in our review that
improved weight loss outcomes would be achieved through the early establishment of behavioural
changes but this was not clearly demonstrated by our results. A systematic review [14] showed that
acute pre-operative weight loss was associated with post-operative weight loss but this was based only
on observational studies. Other studies investigating pre-operative weight loss, but not meeting our
inclusion criteria, have also found mixed results [43, 44]. The degree to which participants are
motivated to engage with lifestyle interventions pre-operatively may be considerably lower than in the
post-operative period, perhaps due to unrealistic expectations of surgically-induced weight loss.
Therefore attempting to introduce lifestyle changes that participants may not believe will be
necessary, could be ineffective. Heinberg and Schauer [45] speculate that this may partly explain the
13
lack of significant difference between the intervention and control groups of their 12-week preoperative study of a portion-controlled, low-calorie diet for BS candidates. If post-operative support
for behaviour change were more effective than pre-operative support it might be attributable to
participants’ motivation to maintain the weight loss momentum induced by surgery. Conversely,
where eligibility for BS is subject to a lower weight or BMI limit, patients could be less motivated to
lose weight pre-operatively if there is a possibility of becoming ineligible for surgery.
The inclusion criteria to inform the aforementioned NICE guidance were RCTs or systematic reviews
of RCTs, published from 2006 onwards but no systematic reviews of RCTs were identified. Our
review has demonstrated further RCT evidence to lend weight to the recommendation of postoperative behavioural interventions. However, the evidence identified by our review could not
establish any difference in effectiveness between pre- and post-operative behavioural interventions.
We cannot draw robust conclusions regarding the recommendation of post-operative in preference to
pre-operative delivery of intervention.
NICE guidance [9] recommends that BS care should include psychological support before and after
surgery as well as specialist dietetic follow-up. Presently, there is little evidence from RCTs that input
from psychologists or psychotherapists results in improved weight loss outcomes. None of the three
trials [21, 23, 28] providing sessions run by psychotherapists found statistically significant differences
in weight outcomes between the intervention and control groups. This concurs with Beck and
colleagues’ systematic review findings [17] from non-randomised studies that group
psychotherapeutic interventions did not result in greater weight loss than support groups without
psychotherapist leadership. Nevertheless, it is plausible that psychotherapy could have a beneficial
effect on QoL outcomes, depression, binge eating or other psychological conditions, which could in
turn lead to improved weight loss outcomes in the long-term, but there were insufficient data in the
included trials to investigate such a hypothesis.
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Hopkins and colleagues’ [46] analysis of outcome reporting in 39 RCTs and 51 prospective studies of
BS found considerable variation in weight loss outcome measures. Percent EWL was the most
commonly reported but 25% of studies did not report weight loss outcomes at all. Clinical guidelines
are also unclear about preferred outcome reporting; the UK’s NICE guidance [40] stipulates no single
preferred outcome but recommends either % weight loss measured in kg or BMI units, or %EWC.
Van de Laar [47] advocates reporting % weight loss, not %EWC, due to its independence from initial
BMI. The range of methods for measuring weight and weight loss in the studies included in our
review made meaningful comparisons difficult. The fact that statistically significant differences were
found in our meta-analyses of weight change at 12 and 24 months and %EWC at 12 months’ followup, but not in absolute weight and BMI at the same time points, raises questions around the most
appropriate methods of reporting weight outcomes.
Our findings add to those of Rudolph and Hilbert’s systematic review [16] of post-operative lifestyle
interventions, which indicated that receiving an intervention post-operatively resulted in improved
weight loss outcomes at 12 months after surgery. We identified several RCTs not included in Rudolph
and Hilbert’s review and we were able to provide some evidence that lifestyle interventions may
enhance weight loss beyond 12 months after surgery. Furthermore, we included pre-operative as well
as post-operative interventions in our analysis. However, given the limited evidence available
regarding the effectiveness of pre-operative behavioural interventions, it remains unclear whether
such support could also be beneficial for BS patients. Kalarchian and colleagues [48] conclude from a
non-systematic literature review that lifestyle interventions are likely to be beneficial for BS patients
but that there is a paucity of evidence relating to what works, in what circumstances and for whom.
Our systematic approach has helped to identify those evidence gaps more precisely,
Future RCTs should investigate the effects of physical activity programmes with concurrent
counselling based around dietary support and behaviour change advice. Given the evidence from
observational studies that s substantial proportion of bariatric surgery patients begin to regain weight
in the first two post-operative years [4, 6, 7], participants should be followed up for at least two years
15
post-operatively to allow sufficient time for any effects of an intervention to become apparent. Based
on the identified evidence gap regarding the most appropriate time point for delivering behavioural
interventions for BS patients, it may be appropriate to compare the effectiveness of the same
behavioural intervention delivered pre-operatively and post-operatively. Future trials should measure
QoL and remission rates of co-morbidities, in addition to weight outcomes, and should ensure
effective strategies to recruit and retain adequate numbers of participants are used. Although it was
not within the scope of this review, the extent to which lifestyle interventions should be tailored to the
type of surgical procedure may need to be investigated.
There is currently little consensus regarding the most appropriate method of reporting weight change.
To facilitate straightforward comparisons between studies it would be beneficial for future studies to
report %EWC and absolute weight in addition to % weight change, which takes baseline values into
account.
Strengths and limitations
The main strengths of our review are the application of strict criteria to include only RCTs, the
systematic approach to quality assessment and evidence identification, including successful contact
with study authors to obtain additional useful data, and adherence to an a priori protocol.
Our findings are limited by the methodological quality and small sample sizes of the included studies.
Few long-term trials were identified and synthesis of primary outcome data was problematic due to
the heterogeneous methods used for reporting weight data. Heterogeneity of behavioural interventions
also presents challenges to evidence synthesis because like-for-like comparisons are impractiable.
Limited reporting of clinically important outcomes meant that no conclusions could be drawn
regarding co-morbidities relevant to this population.
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Conclusion
Delivering behavioural interventions in addition to BS appears to result in improved post-operative
weight loss outcomes for people with severe obesity. The evidence base is stronger for post-operative
interventions than for delivering interventions pre-operatively. However, these conclusions should be
interpreted with caution; the evidence presented here is limited by the relatively small number of trials
identified and by their low methodological quality and short follow-up duration. Well-designed RCTs
with at least two years’ post-operative follow-up are required to evaluate the effectiveness of
behaviour change and dietary support with physical activity.
Conflicts of interest
The authors, Fiona Stewart and Alison Avenell, declare no actual or potential conflicts of interest.
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22
Table 1: Characteristics of included RCTs (NR not reported, LAGB laparoscopic ajustable gastric banding, VBG vertical banded gastroplasty, *mean (range), ** mean (IQR), # mean (SEM)
Study ID,
country
Procedure
Group
N randomised
Female
Age
(years)
mean (SD)
Weight (kg)
mean (SD)
BMI (kg/m2)
mean (SD)
90%
44.1 (12.1)
116.0 (20.0)
46.3 (5.5)
77%
46.2 (12.7)
126.0 (31.0)
44.7 (7.1)
Length of followup
PRE-OPERATIVE INTERVENTIONS
Parikh 2012 [25]
USA
Lier 2012 [21,
49]
Norway
LAGB
Gastric
bypass
Behaviour change counselling (individual)
Behaviour change counselling (group)
Waiting list
15
15
30
Cognitive behavioural therapy
49
73%
43.5 (11.1)
132.9 (17.7)
45.5 (4.3)
50
64%
42.4 (9.1)
133.1 (23.7)
45.1 (5.9)
50
88%
42.4 (10.5)
130.9 (18.2)
48.7 (42-55)*
50
80%
44.9 (7.8)
138.7 (21.7)
49.2 (43-46)*
82
80
74%
76%
45.6 (11.1)
44.8 (10.6)
143.8 (29.2)
140.9 (27.0)
50.4 (7.3)
50.9 (8.3)
66
89%
41.3 (9.7)
107.3 (19.9)
38.8 (6.1)
62
87%
41.9 (10.3)
105.7 (25.1)
38.3 (6.9)
24
83%
44.9 (11.3)
118.5 (105.4-131.3)**
42.8 (36.7-46.7)**
23
78%
44 (10.0)
110.5 (102-126.6)**
40.3 (36.9-44.4)**
72
86%
44.2 (12.6)
94.6 (21.2)
35.4 (6.83)
72
81%
44.8 (14.4)
100.3 (24.9)
36.5 (7.0)
NR
NR
41
95%
84%
41.7 (9.1)
39.7 (7.6)
197.5 (85.0)
166.5 (71.0)
50.7 (8.7)
46.3 (9.4)
12 months
63%
42 (9.9)
152.7 (33.7)
51.6 (9.2)
24 months
150.7 (41.9)
48.9 (11.2)
133.2 (22.4)
47.6 (7.1)
Usual care; two seminars on surgical
procedure and diet
Asked to achieve ≤ 10% excess weight loss
Solomon 2009
Gastric
(EWL) pre-operatively
[34, 35] USA
bypass
No intervention
PRE- AND POST-OPERATIVE INTERVENTIONS
Ogden 2014 [23,
Gastric
Bariatric rehabilitation service
50] UK
bypass
Usual care
6 months
12 months
12 months
12 months
POST-OPERATIVE INTERVENTIONS
Coen 2015 [29]
USA
Gastric
bypass
Dodsworth 2010
[20]
Australia
LAGB
Nijamkin 2012
[22, 51] USA
Gastric
bypass
Swenson 2007
[27] USA
Gastric
bypass
Sarwer 2012 [26]
USA
Tucker 1991 [28]
USA
Any
Gastric
bypass or
VBG
Health education sessions + semisupervised exercise programme
Health education sessions alone
High protein diet + 15 g/day of 100% whey
protein isolate added to any food/drink
Usual dietetic care
Dietary counselling. Advised to consume
1000-1400kcal and 60-70g protein per day
Brief printed guidelines for healthy eating
and physical activity
High protein diet: South Beach Diet37
Standard post-operative low fat diet
Dietary counselling
Usual care; encouraged to attend support
groups
Written materials on weight management
and behaviour change counselling
Self-reported food diaries pre- and postoperatively
6 months
12 months
12 months
43
NR
65%
40.2 (NR)
NR
23
66%
24 months
Papalazarou
2010 [24] Greece
VBG
Dietary counselling
Usual care
15
15
24
100%
100%
32.7 (1.6)#
33.4 (2.0)#
129.5 (NR)
133.3 (NR)
48.5 (8.1)
49.8 (6.2)
36 months
Figure 1: Screening process
Studies identified through
database searching
n = 2491
Studies identified through
alternative sources
n=2
Excluded
n = 2401
Excluded
n = 77
Full text articles
assessed for eligibility
n = 92
•
•
•
•
•
•
•
•
•
•
31 not RCT
17 retained for background
9 follow-up ˂ 6 months
6 review/protocol/retraction/comment
2 ˃ 12 months between surgery and
intervention
2 no weight change data
4 ineligible intervention
4 ineligible comparator
1 no relevant data
1 animal study
Included
n = 11 (15 reports)
Included in meta-analysis
n=8
Figure 2: Summary of risk of bias
25
Figure 3: weight (kg) at 12 months
Figure 4: %EWC at 12 months
26
Figure 5: Weight change (kg) at 12 months
27
Figure 6: BMI (kg/m2) at 12 months after surgery
28
Figure 7: weight (kg) at 24 months
Figure 8: weight change (kg) at 24 months
Figure 9: %EWC at 24 months
29