Background: Adults with severe obesity [body mass index (BMI) of ≥ 35 kg/m2] have an increased risk of
comorbidities and psychological, social and economic consequences.
Objectives: Systematically review bariatric surgery, weight-management programmes (WMPs) and orlistat
pharmacotherapy for adults with severe obesity, and evaluate the feasibility, acceptability, clinical
effectiveness and cost-effectiveness of treatment.
Data sources: Electronic databases including MEDLINE, EMBASE, PsycINFO, the Cochrane Central Register
of Controlled Trials and the NHS Economic Evaluation Database were searched (last searched in May 2017).
Review methods: Four systematic reviews evaluated clinical effectiveness, cost-effectiveness and qualitative
evidence for adults with a BMI of ≥ 35 kg/m2. Data from meta-analyses populated a microsimulation
model predicting costs, outcomes and cost-effectiveness of Roux-en-Y gastric bypass (RYGB) surgery and
the most effective lifestyle WMPs over a 30-year time horizon from a NHS perspective, compared with
current UK population obesity trends. Interventions were cost-effective if the additional cost of achieving a
quality-adjusted life-year is < £20,000–30,000.
Results: A total of 131 randomised controlled trials (RCTs), 26 UK studies, 33 qualitative studies and
46 cost-effectiveness studies were included. From RCTs, RYGB produced the greatest long-term weight
change [–20.23 kg, 95% confidence interval (CI) –23.75 to –16.71 kg, at 60 months]. WMPs with very
low-calorie diets (VLCDs) produced the greatest weight loss at 12 months compared with no WMPs.
Adding a VLCD to a WMP gave an additional mean weight change of –4.41 kg (95% CI –5.93 to
–2.88 kg) at 12 months. The intensive Look AHEAD WMP produced mean long-term weight loss of 6%
in people with type 2 diabetes mellitus (at a median of 9.6 years). The microsimulation model found that WMPs
were generally cost-effective compared with population obesity trends. Long-term WMP weight regain was
very uncertain, apart from Look AHEAD. The addition of a VLCD to a WMP was not cost-effective compared
with a WMP alone. RYGB was cost-effective compared with no surgery and WMPs, but the model did not replicate long-term cost savings found in previous studies. Qualitative data suggested that participants could
be attracted to take part in WMPs through endorsement by their health-care provider or through perceiving
innovative activities, with WMPs being delivered to groups. Features improving long-term weight loss included
having group support, additional behavioural support, a physical activity programme to attend, a prescribed
calorie diet or a calorie deficit.
Limitations: Reviewed studies often lacked generalisability to UK settings in terms of participants and
resources for implementation, and usually lacked long-term follow-up (particularly for complications for
surgery), leading to unrealistic weight regain assumptions. The views of potential and actual users of
services were rarely reported to contribute to service design. This study may have failed to identify
unpublished UK evaluations. Dual, blinded numerical data extraction was not undertaken.
Conclusions: Roux-en-Y gastric bypass was costly to deliver, but it was the most cost-effective
intervention. Adding a VLCD to a WMP was not cost-effective compared with a WMP alone. Most WMPs
were cost-effective compared with current population obesity trends.
Future work: Improved reporting of WMPs is needed to allow replication, translation and further
research. Qualitative research is needed with adults who are potential users of, or who fail to engage
with or drop out from, WMPs. RCTs and economic evaluations in UK settings (e.g. Tier 3, commercial
programmes or primary care) should evaluate VLCDs with long-term follow-up (≥ 5 years). Decision models
should incorporate relevant costs, disease states and evidence-based weight regain assumptions.
Study registration: This study is registered as PROSPERO CRD42016040190.