We of course welcome the fact that the issue of obesity and diabetes in the management of psychosis is taken seriously by the disciplines represented in this conference (1). However, as clinical psychiatrists we are concerned that some of the matters raised may give an unintentionally misleading message.
We are far from sure, for example, that the evidence supports the view that there is so much disparity in the incidence of obesity and diabetes among first-generation antipsychotics (FGAs) and second-generation antipsychotics (SGAs). Furthermore, there is no evidence, for that matter, of disparity between the experience in schizophrenia now and during the preantipsychotic period, especially from the 1920s onwards following the discovery of insulin. It seems likely that schizophrenia itself represents a significant risk factor for obesity and diabetes.
Moreover, concurrent substance abuse (especially of tobacco and cannabis) is frequent among this patient population (2), and this, along with well-established factors such as low activity, sedentary lifestyle, smoking, and, above all, poor diet (with reliance on processed and “junk” food), makes arguably the most significant contribution to the development of obesity, dyslipidemia, and diabetes. Relative risk due to family history or ethnicity is also highly relevant.
A failure to take these major confounding factors into account vitiates many of the conclusions concerning the metabolic effects of SGAs in recent literature. We do not think that there is currently any sufficient evidence to distinguish among antipsychotics (FGAs or SGAs), and we would not feel comfortable telling patients that a particular drug would not add to the risk of developing diabetes.
We are most anxious about the recommendation that “[i]f a patient gains >5% of his or her initial weight at any time during therapy, one should consider switching the SGA” (1). Weight fluctuation is common, can have many causes, is usually diet related (patients may be eating more regularly in the hospital than when in the community or they may have more appetite during the recovery phase of their illness), and may occur after treatment initiation but before the full therapeutic effect. For example, the preliminary data of the large-scale SOHO study (3) of over 10,000 European patients indicate that ∼48% of patients put on >3 kg in weight over 1 year of treatment.
To follow literally the consensus advice could be potentially highly detrimental to the patient’s treatment. We recognize that the cost-benefit balance is duly recognized and that the recommendation that switching should be considered does not command that switching must be done. But even the recommendations of a prestigious consensus panel have the force of law in the wider professional community, not to mention the pressure from consumers and their advocates who similarly take the recommendation as a command, considerably increasing the exposure of prescribers to litigation.
