Clinical Staging of Psychiatric Disorders

¶ … DSM diagnostic criteria have long been a source of criticism. McGorry, Hickie, Yung, Pantelis, and Jackson (2006) point out some basic deficiencies of the DSM diagnostic system. First the authors state that the function of a diagnosis is to state what treatment should be applied or predict the prognosis of the condition. These are certainly functions of a diagnosis, but a diagnosis has broader implications. First and foremost the idea of having a diagnosis is to take a series of related signs and symptoms that hang together consistently and label them so as to facilitate communication between health care professionals. A diagnosis alone is useless unless it allows professionals to communicate about the same entity. Then descriptions of course, treatment, and prognosis can follow.

McGorry et al. charge that in the DSM system the clinical features that occur early in the course of the disorder are not distinguished from those that occur later and that treatment is more effective early in the disorder. The goal of the DSM diagnostic criteria has always been on reliability, which sets the upper limit for validity but does not ensure validity. McGorry are concerned with a valid diagnostic method which can assist in more effective treatment. They support a clinical staging approach that is allegedly a more refined form of diagnosis than the DSM classification system. Clinical staging differs from the traditional DSM diagnostic practice in that instead of looking at a bunch of co-occurring symptoms and fitting them into a diagnosis it attempts to define the extent of progression of a disease at the time of the assessment. Clinical staging stresses that greater emphasis be placed on a description of where the patient lies on the continuum of the course of the particular illness, from early to late in its course. Clinical staging has been successfully applied to several different physical diseases; most successful applications have been to different types of cancers. McGorry et al. state that this method can be applied to any disorder that progresses or may progress. In other medical conditions clinical the clinical stages are defined by biological markers and their impact on the patient. McGorry et al. present a proposed table for the clinical staging of psychotic disorders and severe mood disorders. In the McGorry scheme social markers are also present, but these "objective" staging criteria which include GAF scores and other staging criteria that are more subjective than objective.

There are numerous issues with this approach. First, and the main problem here, is that there are no universal recognized clinicopathological signs for the vast majority of disorders described in the DSM system. McGorry et al. describe the results of studies that indicate that lower hippocampal volumes are found in the brains of severely depressed people and schizophrenics, lower frontal cortex volumes in schizophrenics, etc. But what the researchers fail to mention is that not a single one of these markers is pathonomonic of any disorder. In fact, even such taken-for-granted psychological markers like lower Serotonin levels have never been empirically demonstrated in sufferers of clinical depression, even though psychiatry still purports this as a cause of depression (Kirsch, 2010). Psychiatric disorders are not like physical diseases such as cancer that have a well-defined clinicopathological progression. Moreover, McGorry et al. fail to mention either by intent or ignorance that many of these neuro-findings in psychiatric populations occur only in patients who have taken psychiatric medications for a substantial period and it may be the medication that is responsible for the "marker" (Kirsch, 2010). There are no pathonomonic physical markers for the majority of disorders in the DSM. There are no blood tests or clinical medical tests that can diagnose psychiatric disorders. Clinical staging is aimed at physical diseases like cancer and of course the psychiatrists have long tried to classify DSM disorders in this category, but there is no substantial evidence that they are physical diseases, and this is especially true of biological or physical signs associated with a psychiatric disorder.

There are several different staging models for psychiatric disorders (and there will probably be more due to the lack of biological markers). The earliest of these came from Fava and Kellner (1993). The problem is that the staging models have important conceptual differences between them. For instance the second stage in the McGorry et al. model is very different from the same stage in models proposed by Fava & Tossani (2007) and Hetrick, Parker, Hickie, Purcell et al. (2008). A review of the research indicates that separate clinical staging models have been developed for different mental disorders, but there is not a united approach that can be applied across a broad range of disorders. What would the clinical staging of ADHD require? There is not a single model that has been routinely applied to clinical practice and as of this writing there has no relevant research on the validity of these models.

The real issue with the DSM is that the diagnostic criteria for the disorders are determined by committee and not by empirical research, unlike all other fields of medicine. In addition, DSM committee members often have strong financial ties to pharmaceutical companies and this certainly affects the validity of the DSM system (Turner, Matthews, Linardatos, Tell, & Rosenthal, 2008). What assurance do we have that the same would not happen to clinical staging models?