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Psychosocial assessment: is it always necessary?

An article in issue 11 of Bariatric News raised a debate among our readers - is psychosocial assessment always necessary?

According to Dr Tom Stevens, a consultant psychiatrist at St George's Hospital and South London and Maudsley NHS Trust, UK, is a necessary part of a successful bariatric operation. Dr David Ashton, medical director at Healthier Weight Centres and honorary senior lecturer in clinical epidemiology at Imperial College School of Medicine, disagrees, saying that contrary to received wisdom, pre-operative mental health evaluation is another form of prejudice lacking empirical evidence and adding nothing to clinical decision making or patient outcomes.

Yes - Dr Tom Stevens

Tom Stevens.

The morbidly obese are yet another group who face discrimination and stigma reminiscent of the medieval homeless, poor, sick and insane and for whom the first hospitals were built. The influence of psychosocial factors on health outcomes needs no explanation and no doctor would advocate that a psychosocial history is unnecessary.

Sadly when physicians all too regularly instruct the obese to eat less and exercise more, the psychosocial context of their weight including guilt, adversity and failure is often overlooked. The psychosocial contribution to eating behaviors is often better understood by patients who distinguish between ‘emotional eating’ and ‘hungry eating’ in their mutual support groups.

“So what can mental health professionals do? Much the same as any other member of the team. They can advise on risk like an anaesthetist, give opinions on diagnosis, suggest investigations and treat mental illness and liaise with other mental health teams.” Dr Tom Stevens

The traditional view that rates of mental illness are no higher in those presenting for bariatric surgery has has not withstood more detailed scrutiny. Recent studies have identified high rates of depression, eating disorders, psychiatric admission and self-harm preceding surgery. These indices of ill health have not depended on conflating obesity and eating disorders, a criticism frequently leveled at psychiatric analysis of obesity.

The high rates are possibly related to the high background incidence of adversity. Rates of sexual abuse are in the order of 20%, although much higher rates of adversity are seenAny clinician working with this population will notice extraordinary patterns of weight gain in response to adversity that can mirror weight changes seen with hypothalamic injury.

For any neuroscientist it is no surprise that peripheral neurohumoral feedback on the CNS and mental illness and stress might have similar impacts on the complex nature of eating behaviours and weight. I have noted that many patients with weight gain associated with adversity often explain their obesity in terms of a reaction to this.

Tom Main warned physicians of the complex relationships that emerge with patients who have experienced adversity. His famous quote ‘Cured patients do their physicians great service’, highlights the particular pitfalls for the doctor patient relationship after bariatric surgery where patients fail to allow themselves to be ‘cured’.

Bariatric surgery has an impressive impact on both health and social functioning which can be reflected in the zeal of many bariatric surgery advocates. However within this context there are a subgroup who appear to do less well. Despite the short-term improvement in global measures of mental health for most, suicide rates appear to increase.

For some, surgery is seen as an escape from the vicissitudes of a difficult life. Expectations of new roles, relationships, opportunities and health can be unrealistic.

“Sometimes it is only after repeated failure and growing behavioral dysfunction that the mental health professional is asked for an opinion to provide a different perspective on the problem.” Dr Tom Stevens

When unrealistic expectations are combined with complications, poor tolerance or inadequate weight loss relapse of otherwise stable mental disorder can be triggered. Where there is inadequate weight loss and great despondency, demands for further surgery can provoke particular challenges for the surgeon.

Sometimes it is only after repeated failure and growing behavioral dysfunction that the mental health professional is asked for an opinion to provide a different perspective on the problem. The patient may be construed as at fault having ‘failed’ to respond to the intervention.

When the mental health professional fails to effect a satisfactory outcome, this reconfirms the belief that they have no useful role to play.

In addition to disordered post-operative mood and self-harming behaviour are reports of anorexia type syndromes appearing and higher rates of Wernicke’s encephalopathy in those reverting to alcohol. The absence of adequate prevalence data on post-operative psychiatric complications reflects the dearth of active involvement of mental health professionals in post-operative care in this group. 

Psychiatry and psychology have been criticised for being unable to predict weight loss outcomes after surgery and acting counter to those whose interests they are supposed to be advocating, by discriminating against them and blocking access to surgery. Some programmes have excluded up to 20% of patients following psychological and psychiatric review.

This perspective is now out of date, with a consensus emerging that the mental health professionals need to be involved both pre- and post-operatively in optimising preparedness for surgery and psychological adaptation to the operation.

The emerging literature suggests that preoperative prediction of psychosocial outcomes and quality of life is better than prediction of weight loss and suggested by more severe psychiatric disorder and multiple diagnoses. Post-operatively, loss of control and self monitoring behaviour are able to predict weight loss and weight regain.

So what can mental health professionals do? Much the same as any other member of the team. They can advise on risk like an anaesthetist, give opinions on diagnosis, suggest investigations and treat mental illness and liaise with other mental health teams. Where they are embedded in the MDT, transfer of skills and knowledge is facilitated and conflict is minimised.

Many patients request to see a psychologist or psychiatrist, where they are available. So why would you advocate that a mental health professional should not be part of the multidisciplinary team.

No - Dr David Ashton

Dr David Ashton 

Contrary to received wisdom, pre-operative mental health evaluation in obese patients is just another form of prejudice, lacking any credible empirical evidence and adding nothing to improve clinical decision making or patient outcomes. 

Pre-operative psychological assessments

Pre-operative psychological testing in weight loss surgery patients is both widely recommended and common in practice. As a consequence, up to one quarter have their surgery deferred or denied.

The stated aims of such testing are (1) to evaluate psychopathology in patients presenting for obesity surgery and (2) to identify those candidates for whom the probability of a successful outcome (primarily weight loss) is low.

Psychopathology in obesity surgery patients

There is substantial evidence to suggest that candidates for obesity surgery exhibit a high prevalence of psychopathology, including depression, anxiety and binge eating disorder. Sarwer et al found some two thirds of surgical weight loss patients received a pre-surgery psychiatric diagnosis, the commonest of which was a major depressive disorder.

“Because obesity is not fundamentally a psychological problem, psychological variables have so little predictive power. No amount of statistical manipulation of mountains of data on the part of psychologists or other advocates of screening will make the slightest difference to the outcome. They are chasing a chimera.” Dr David Ashton

However, there are serious methodological problems with many such studies which suggest their conclusions are not as secure as they may appear. 

Firstly, there is lack of concensus concerning which instruments should be used for pre-operative screening and considerable controversy regarding their validity. Even the authors of the Diagnostic and Statistical Manual of Mental Disorders (DSM) acknowledge that its diagnostic and criterion sets are highly questionable.

Secondly, there is wide variability in the way pre-operative assessments are performed.

For example, some investigators used unspecified clinical interviews to assess patients; some used DSM criteria to classify patients while others did not specify the diagnostic criteria; some studies focused on current psychiatric diagnosis, whereas others based results on both current and lifetime occurrences of disorders combined.

Importantly, few studies have included a control or comparison group, making meaningful interpretation of these data difficult. 

In fact, pre-operative studies in other groups of surgical patients also show high levels of psychopathology, confirming the common sense intuition that bariatric patients are not unique in this regard(1, 2).

So the obvious question is why pre-operative psychological testing should be so widely regarded as essential for weight loss surgery patients, when we do not routinely recommend it in patients undergoing cancer surgery or joint replacement?

The only plausible answer is that test results in obese patients can be used to predict poor post-operative outcomes, thus facilitating better patient selection. But what is the evidence for this?

Predicting poor post-operative weight loss

In 2008, colleagues and I published a detailed review of the literature on pre-operative psychological testing for surgical weight loss patients. Our conclusion, consistent with other large systematic reviews, was that no psychological factors identified pre-operatively, reliably predict post-operative outcomes.

Indeed, what was most striking about the studies was the consistent lack of association. (Some studies had even reported a positive association between psychopathology identified pre-operatively and post-operative outcomes, including weight loss). 

Individual studies which have reported an association between pre-operative variables and post-operative weight loss, tend to exhibit similar, flawed methodologies.

A recent publication by Belanger et al is a perfect example. Investigators recruited 143 surgical weight loss patients who were screened at baseline with a variety of psychological tests, consisting of no fewer than 742 items in total. The candidates were then split into five groups based on their baseline assessment.

Two groups were excluded from the study for reasons which are not entirely clear and the remaining three were followed for six months.

The authors then performed a variety of complex statistical analyses involving square root and logarithmic transformations, to reach the conclusion that certain pre-operative variables identified on some test sub-scales, predicted greater weight loss at six months. 

Unfortunately the authors do not report the magnitude of the weight loss in each group, so one cannot know precisely what is meant by “greater” weight loss. Furthermore, given the “shotgun” approach to the study – apply a huge number of variables and hope that something turns up – it would surely be more surprising if no associations were found.

In fact, a simple calculation of changes in BMI reveals the percentage reduction in BMI across the three groups was 29.6%, 29.8% and 28.2%. This suggests that whilst the differences may be statistically significant, they are clinically meaningless. 

Prejudice and stigmatisation 

In the 1950s, psychoanalytic theory held that obesity was a manifestation of a basic personality problem which involved acting out unconscious conflicts. Subsequently, behavior therapists argued that it was a learned disorder in which principles of conditioning could explain overeating.

Today, these pseudo-scientific theories have been replaced by a large and consistent body of scientific evidence which shows that body weight in humans is regulated by a complex interaction of genetic, neural, metabolic and hormonal factors.

“The myth that psychological factors are paramount in the aetiology of obesity is itself the expression of a wider societal prejudice, which views the obese as psychologcally and emotionally disturbed, lazy, feckless and morally defective.”Dr David Ashton

Psychosocial factors may contribute, but they are not primary and it is precisely because obesity is not fundamentally a psychological problem, that psychological variables have so little predictive power. No amount of statistical manipulation of mountains of data on the part of psychologists or other advocates of screening will make the slightest difference to the outcome. They are chasing a chimera. 

The view that psychosocial factors are not primary is also supported by the observation that bariatric surgery consistently results in major improvements in depression, anxiety, self-esteem, eating disorders and health-related quality of life (1, 2, 3). Furthermore, the magnitude of the improvement is proportionate to the amount of weight lost.

These findings suggest that psychological co-morbidity in weight loss surgery patients is the consequence of their obesity, rather than the cause. This is why there is no rational basis for using psychological testing as the basis for either deferring or denying weight loss surgery to otherwise eligible patients.

The myth that psychological factors are paramount in the aetiology of obesity is itself the expression of a wider societal prejudice, which views the obese as psychologcally and emotionally disturbed, lazy, feckless and morally defective.

The reason why those undergoing knee replacement or hernia repair or any other routine surgical procedure are not required to undergo pre-operative mental health evaluation, is precisely because (unlike the obese) they are not perceived as being inherently psychologically or morally dysfunctional. 

Conclusion 

The stigma of obesity is strong and pervasive even among healthcare professionals. Pre-operative psychological screening is nothing more than the outward manifestation of this stigma, masquerading as good practice and without any evidential basis. Psychologists have much to contribute in many areas of medicine, but bariatric surgery is not one of them.