Mental health disorders, such as depression, anxiety, body dysphoria, poor self-esteem and eating disorder, are very common in patients with obesity undergoing bariatric surgery [
65]. Bariatric surgery has also been reported to be associated with increased risk of self-harm and suicide. In a systematic review, the post-bariatric suicide event rate was 2.7/1000 patients (95% CI 0.0019–0.0038), and the suicide/self-harm attempt event rate was 17/1000 patients (95% CI 0.01–0.03) [
66]. The self-harm/suicide attempt risk was higher after vs. before bariatric surgery (OR 1.9 (95% CI 1.23–2.95)), and when compared to age, gender and BMI matched control population (OR 3.8 (95% CI, 2.19–6.59)) [
66]. The increased of self-harm occurs following all bariatric procedures although highest post-RYGB [
67]. However, whether these mental health disorders predict post-surgical weight loss is unclear, and studies have shown conflicting results. For example, a systematic review in 2012 found that three studies showed positive associations, 13 studies showed neutral associations, and four showed negative associations between binge eating and post-operative weight loss [
55]. Similarly, with regard to emotional eating, three studies in this review showed neutral associations, and three studies showed negative associations; and in regard to binge eating, three studies reported that patients with pre-operative binge eating lost more weight post-operatively than those without binge eating, thirteen studies reported no association, and four studies reported a negative association [
55]. With regard to depression, one study showed a positive association, fourteen studies showed neutral associations, and four studies showed negative associations, and similar conflicting results were shown in regard to other psychological disorders as well as history of sexual abuse [
55]. The recent British Obesity and Metabolic Surgery Society (BOMSS) guidelines regarding pre- and post-surgical psychological weight management also acknowledged the importance of providing post-surgical psychology support to patients with bariatric surgery [
65]. Particularly that many mental health and eating disorders may recur or occur de novo post-surgery and that these conditions are associated with less weight loss and adverse outcomes when they are present post bariatric surgery [
65]. In addition, it is widely accepted that it is important to address significant mental health disease to ensure that the patients are able to undergo surgery and make informed choices. However, there appears to be a lack of evidence to support or refute whether addressing mental health disorders pre-surgery improve bariatric surgery outcomes as bariatric surgery is consistently associated with post-operative decreases in the prevalence and severity of depression [
68]. The delivery of high-quality psychological assessments and treatments is rather challenging due to the lack of enough psychologists. Hence, alternative strategies are needed including upskilling other members of the multidisciplinary team to perform such duties under the supervision of a clinical psychologist and the reliance on some of the mental health services delivered in the community, although these are not weight management specific.
Has the NHS in England Got It Right? Our View and the Challenges
Despite the modest efficacy of tier 2 services (detailed above), there is still a lack of data on long-term outcomes, and these programmes typically have high levels of dropouts, and also cost-effectiveness can vary according to the program [
23,
69]. However, they are appropriate for a subgroup of patients with overweight or obesity and applicable at a population level where modest weight loss would be meaningful. Nonetheless, these are not widely accessible. Many areas in the UK do not have tier 2 services, and they have an associated cost if privately funded, which is challenging considering that obesity prevalence is higher in people from disadvantaged socio-economic backgrounds which further increase health inequalities.
Tier 3 services, within the current structure, are only accessible for a sub-set of patients with obesity, i.e. those with complex obesity. In patients not requiring or wanting bariatric surgery, tier 3 seems to result in modest, but clinically significant weight loss over a 6–12-month period, although a 10% weight loss which is more meaningful clinically is only achieved in less than 20% of patients as described above. However, the few studies reviewing tier 3 services generally had methodological weaknesses, and cost-effectiveness is unclear due to high dropout rates, the lack of long-term data and the variation in the structure of the programmes. Furthermore, the evidence for impact of tier 3 on outcomes other than weight is very limited, and there is a lack of data in regard to hard outcomes such as mortality or cardiovascular disease. So, in short, for this group of patients, tier 3 appears to be modestly effective, but is it the best way to deliver these benefits? Hence, the current approaches to tier 3 might need to be revisited.
In the context of bariatric surgery, the current tier 3 is almost set up to fail most of its objectives particularly in terms of “selecting” those who are likely to achieve greater weight loss post-surgery and reducing the number of patients needing surgery in a significant manner. It is virtually impossible for tier 3 services to be effective in “selecting” the best candidates for bariatric surgery (in terms of weight loss achieved) due to the lack of evidence to support this selection process and the lack of reliable predictors of outcomes. As a result, whichever criteria used to “select” patients by individual services have become barriers between patients and surgery rather than delivering care and personalizing treatment approaches. In addition, considering the modest weight loss achieved in tier 3, its ability to reduce the need for surgery is likely to be negligible and is based on very simplistic assumptions that do not take into account either the complexity of obesity or bariatric surgery. In addition, it has been shown that patients undergoing bariatric surgery can have unrealistic expectations in regard to weight loss. Therefore, the modest weight loss likely to be achieved in tier 3 will not be satisfactory to the patient in many cases [
70].
However, tier 3 services still have an important role to play in preparing patients for surgery in terms of education, managing patient expectations, addressing and optimizing obesity-related complications prior to surgery and helping patients to make informed choices. In addition, it can identify patients who have complex mental health needs that either need addressing before surgery or require close observation and possibly intervention if persisting after surgery [
71]. Nonetheless, to perform the above-mentioned care, 12–24 months of medical weight management prior to surgical referral may not be required in most patients, and such duration is not supported by evidence. The current structure of tier 3 is overly rigid with little flexibility to allow a patient-centred approach to be used to meet individualized patient needs. For example, patients who develop post-surgical complex nutritional deficiencies, mental health disorders, difficult to treat metabolic complications such as hypoglycaemia, type 2 diabetes recurrence or weight regain would benefit from access to the tier 3 MDT expertise, but currently tier 3 services do not routinely provide input for patients after surgery [
71,
72]. Furthermore, there is currently no data about how to support patients who are discharged from tier 3 back to primary care due to lack of meaningful weight loss, although this could change with the availability of better weight loss pharmacotherapy.
The delivery of integrated weight management pathways faces several challenges. The list below, while not exhaustive, presents some of the main challenges:
1.
Access to treatment: The provision of the integrated pathways is not universal, and there is a “postcode lottery” in terms of what is delivered at a regional and local level. In the recent national weight management, mapping exercise geographical coverage of tier 2 was 63%, but the coverage of tier 3 was not possible to identify due the poor response rate from the clinical commissioning groups (CCGs) (18%) [
7]. A survey of consultant endocrinologists in 2015 showed an estimated coverage of tier 3 of 60% though more formal mapping was not available (J Wass & K Knight, RCP internal communication). As for bariatric surgery provision, this is very limited in the UK with latest estimates suggest less than 0.002% of the potentially eligible adults have surgery annually [
73]. In addition, there are many barriers for referral from primary care to tiers 3 and 4 services even when present, including lack of clear referral criteria, lack of awareness of the services available and their clinical outcomes and funding constraints from the commissioners [
74,
75] resulting in only a median (IQR) 3 [
1‐
7]% of patients with BMI ≥ 25 kg/m
2 referred for weight management intervention in the UK [
76]. This lack of service commissioning and referral to specialist services could be in part due to obesity stigma.
2.
Overall structure: The current tiered system lacks flexibility. While it might have been designed to deliver different levels of care depending on patient needs, the tiers have become hurdles rather than one continuum. There is a need to have flexibility with patients moving through the tiers depending on their clinical needs and response to treatment. There is also rigidity in the tiered system that makes it difficult to cater for patients’ individual needs; for example, patients who require rapid weight loss to get another procedure (e.g. hip operation) who may end up waiting for prolonged periods of time to access services and may or may not achieve the target weight loss to allow their procedure to be performed. In addition, many patients who would require more intensive input in tiers 3 or 4 end up accessing tier 2 first as a pre-condition to progress in the treatment pathway. All that results in further delay and potentially could set up the individual for multiple cycles of “failed” weight loss attempts which have significant negative impact.
3.
Type of patients seen: Although Tier 3 weight management services are supposed to see patients with obesity-related complications, the available data suggest that most patients in tier 3 are free of such complications [
35]. This raises a question about how to make sure that the service is accessible to those with greatest clinical need. It appears that the criteria used currently may disadvantage patients with lower BMIs, but established obesity-related complications, who may have significant clinical benefit from weight loss.
4.
Lack of long-term outcomes and national registry: Unlike bariatric surgery that has the National Bariatric Surgery Register (NBSR), tier 3 services currently do not have a register. This is complicated further by a lack of an agreed core outcome set to measure in tier 3. However, a recently published study identified core outcomes set for tier 2 services [
77]. Many of the contributors to this study also work in tier 3, and many of the outcomes identified in this paper are very reasonable outcomes for a tier 3 service. Recording the same outcomes at a national level for tier 3 would help provide outcome data, including for cost-effectiveness analysis, and potentially identify improved ways to deliver services by learning from those services that are achieving better outcomes.
5.
Bariatric surgery and new treatment modalities: Several new pharmacotherapies with significant weight loss (> 10–20%) are in development, and many patients with obesity will be eligible for these medications. However, currently how Tier 3 services can deliver such treatment, how they will be funded, the eligibility criteria and the treatment duration are not clear. In addition, the delivery formula of low energy diets in primary care as per NHS long-term plan [
78] remains unclear and currently is being piloted by NHS England [
79]. Endoscopic bariatric surgery also is increasingly performed in the private sector but is not widely available in the NHS as yet. In addition, and as described above, only a tiny fraction of people eligible for surgery are able to access it due to multiple factors including lack of funding.
6.
High prevalence of obesity: The adult prevalence of obesity and overweight is 64% and for obesity alone (defined as BMI ≥ 30 kg/m
2) 29% [
80]. This Health Survey for England (HSE) data highlighted the increasing prevalence of obesity over the years (1997 18%; 2007 25%; 2017 29%). Obviously, we do not know the exact number of people with obesity who would like to seek weight management services; but it is likely that this number is substantive considering the high prevalence of obesity-related comorbidities and complications. The recent estimates of those who would be eligible for bariatric surgery in England is 3.6 million adults based on applying NICE criteria [
12] to HSE 2014 data [
73]. Such high demand across all tiers of weight management services is likely to outweigh the capacity of the current integrated pathway, even considering tier 2, which has the largest capacity. In addition, as discussed above, a large proportion of regions do not have access to either tier 2 or tier 3 services.
7.
Referral criteria: The current referral criteria to tier 3 weight management services are largely aligned with NICE guidelines regarding referral for bariatric surgery (i.e. BMI ≥ 35 kg/m2 with complications or ≥ 40 kg/m2 without complications). These criteria deprive many patients who could benefit from tier 3 services from access to the multidisciplinary team and do not take into account individual biological factors such as insulin resistance or beta cell function. Several trials showed that 5–10% weight loss has a favourable impact in patients with obesity-related complications such as pre-diabetes, type 2 diabetes, non-alcoholic fatty liver disease and obstructive sleep apnoea even with a BMI below 35 and in many cases below 30. These patients currently do not have access to tier 3 services.
8.
Obesity stigma: It is increasingly recognized that obesity stigma is very common within the healthcare system and is a barrier to healthcare delivery [
81,
82]. In 2018, the UK All-Party Parliamentary Group on Obesity reported that only 26% of people with obesity reported being treated with dignity and respect by healthcare professionals when seeking advice or treatment for their obesity, while 42% did not feel comfortable talking to their GP about their obesity [
83]. Even experts currently working in obesity demonstrate stigmatizing beliefs [
84,
85]. Weight stigma, both external and internal, is harmful to an individual’s psychological health, experiences of healthcare and long-term physical health [
86,
87]. Stigma may in part be due to the lack of understanding of the biological causes that drive excess weight amongst healthcare professionals, decision-makers and the public [
88]. Hence, there is a need to combat obesity stigma both within and outside the healthcare system. This will require concrete action from policy-makers, improve obesity education in undergraduate curriculums and educate healthcare professionals about obesity and how to avoid stigma. In an attempt to address the latest point, a consensus statement from multiple obesity experts and patients from the UK was issued [
89].
Some of these challenges are addressed in the BOMSS and multi-collegiate commissioning guidelines for complex obesity services [
90,
91]. These guidelines provide a detailed framework to what should be delivered by primary care and specialist weight management services, the multidisciplinary team structure and quality standards to assess performance. These guidelines still face some challenges including the increased workload of primary care physicians and the training requirements. In addition, increased funding is likely to be required to implement these guidelines, but this could prove challenging due to the lack of clear cost-effectiveness of the current tier 3 services.