Introduction

Psychiatric diagnosis is based in the clinical presentation which is made into objective data by the mental state examination performed by a Psychiatrist. The mental state depends on the patient's life story, the evolution of the disease and the current state. So far, there aren't many objective means to helps us obtain a diagnosis so the psychiatric diagnosis is framed by diagnostic criteria such as Diagnostic and Statistic Manual of Mental Disorders (DSM) or the International Classification of Diseases (ICD). Although there are clinical presentations that can point us towards a diagnosis, there aren't any pathognomonic symptoms of any kind of Psychosis¹.

For the accurate diagnosis of an entity it's crucial to include a longitudinal evaluation which requires a long follow up. Therefore, diagnostic uncertainty is part of the psychiatric evaluation.

Since the early classification systems proposed and until the most recent criteria systems, one of the main features of a psychiatric diagnosis is its stability over time - the more stable one diagnosis is, the more likely it is to represent a consistent pathophysiologic process². Diagnostic stability² reflects how a diagnosis is maintained over consecutive evaluations of the same patient.

Diagnosis is important for the treatment and prognosis but also the investigation field which needs to be uniform and replicable creating homogeneous groups allowing aetiology, pathogenesis and treatment studies to take place¹.

There can be various causes for variability or diagnostic instability as presented by

Spritzer et al. (1987): subject variance (change in patients), occasions variance (differences between different episodes), information variance (new or better information), observation variance (different clinical interpretation) and criterion variance. Only the quality of the clinical evaluation and the tools to obtain information can be trained in order to improve clinical abbilities¹. This is of utmost relevance in psychotic disorders as they tend to have a chronic course leading to long term treatment frequently based on an early diagnosis.

We aim to evaluate the diagnostic stability of our ward using the diagnosis at discharge.

Materials and Methods

This is an observational, naturalistic, longitudinal and retrospective study based on discharge diagnosis of the Psychiatric Ward at the Psychiatric Department of Centro Hospitalar Gaia/Espinho from January 2005 until December 2016. From the 5422 admissions representing 3138 patients we selected those with more than one admission (n = 966). From this data pool we analysed those with at least one admission having one of our diagnosis of interest for the purpose of this study -Primary or Secondary Psychotic Diseases. We then came to a 507 patients sample (n = 507).

We decided to use the diagnosis at discharge from our ward as these are mandatory to be filled and they are assumed to be more acurate³ because of the type of continued and multidisciplinary evaluation with families and because in this setting we have the opportunity to use the information previously collected by the attending psychiatrist. Using this information registered by the attending psychiatrist can be useful in order to better understand the evolution of the disease but it can also lead us to maintain a previously assigned diagnosis. In our unit the classification in use during this period was still the International Classification of Diseases 9 (ICD 9).

We decided to study diagnosis stability using major disease groups as it didn't seem relevant to analyse differences associated with different phases of the same condition.

The data were analysed using Excel and SPSS and this study was approved by the Ethics Committee of Centro Hospitalar Gaia / Espinho.

Results

The prospective general stability in this sample was of 54% which states the proportion of individuals who maintained the same diagnosis of a specific Psychotic Disorder in the latest discharge comparing with the first admission discharge. We assumed the latest discharge as Gold Standard as this was stablished with more information (previous data and longitudinal data). Table 1.

As expected, the diagnosis with higher stability were those of the major psychiatric syndromes: Schizophrenia with 77% stability and Bipolar Disease (BD) with 69% stability. Depressive psychosis patients were those with a surprisingly low stability of only 8%.

About a third of individuals (32%) initially diagnosed as having Drug Induced Psychosis had a diagnostic shift towards Schizophrenia. However, 21% of those with a first admission diagnosis of Drug Induced Psychosis were latter readmitted with a diagnosis outside the scope of this paper, which means, a non psychotic one. It is also relevant to point out that we focused on readmitted patients, therefore, we can't extrapolate the percentage of Schizophrenia conversion in these patients - that would be an important issued to be addressed in further studies.

Discussion

Schizophrenia diagnosis implies a longitudinal evaluation with several clinical data and a careful differential diagnosis as it carries a burden of stigma and chronicity. We hypothesize that this is why it is the diagnosis with greater prospective stability with 77% of patients maintaining it. 9,4% shifted towards a Schizoaffective Disorder (SQA), a reasonable number if we consider that only after a major depressive episode or a manic episode can we come to this diagnosis. Only 4% of these patients shifted towards a Bipolar Disorder, a true diagnosis reclassification, which can be questionable or question the previous diagnosis - after an affective episode, in a patient with previous psychotic symptoms meeting criteria for a Schizophrenia Diagnosis, the diagnosis to assume should be one of Schizoaffective Disorder. To point out that from the 180 patients initially diagnosed as Schizophrenic, only one shifted to Paranoia and none evolve into a Drug Induced Psychosis although we it is known that sometimes drug use is maintained.

Schizoaffective Disorder shows a reasonable prospective diagnostic stability of 54% (similar to that of the total sample). To point out that 23% of these patients shifted towards a diagnosis of Schizophrenia. This transition, as previously stated in this paper, raises some issues: the previous medical information wasn't taken into consideration? Was it not considered trustworthy? This is of the most importance as it can have therapeutics and prognostic consequences in these patients. None of the those initially diagnosed as having Schizoaffective Disorder were latter diagnosed with Bipolar Disorder.

Depressive psychosis refers to a diagnosis of an episode of a morbid state which, although implying surveillance and the risk for a new episode, doesn't necessarily implies chronicity or irreversibility. Therefore, only 8% of these patients maintained the diagnosis and about 68% shifted towards a diagnosis outside the scope of this paper in a later admission. However, 8% shifted towards Schizoaffective Disorder and 12% to Bipolar Disorder, none was later diagnosed as Schizophrenic.

Bipolar Disorder shows a high diagnostic stability of 69%. 7,2% were reclassified as Schizophrenic raising, once again, the issue: were the previous data dismissed? What new data lead to this reclassification over Bipolar or Schizoaffective Disorder? Despite these questions, 8,8% were reclassified as Schizoaffective patients, presumably presenting one or more psychotic episodes in the absence of major affective symptoms.

From the 50 patients initially diagnosed with Paranoia only 36% maintained it in the most recent evaluation. This diagnosis shows a relatively low stability which could be explained by new data surfaced (personality or functionality compromise, major affective symptoms, etc.) Therefore, 28% were reclassified in later admissions as Schizophrenic and 6% as Bipolar.

Non organic psychosis includes atypical psychosis, briefor reactive psychosis and also those cases where the admission episode wasn't enough for a clear major syndrome diagnosis. Only 18% of patients maintained this diagnosis. 20,9% shifted to Schizophrenia and 6,7% to Schizoaffective Disorder, 10,6% to Bipolar and 7% to Paranoia. One out of three (33%) was diagnosed as having a diagnosis outside the scope of this paper.

Limitations

Despite being a relevant contribution to the discussion on psychiatric diagnosis, this paper has its own limitations. It is a naturalistic study in which there were no clinical revaluations nor there were used clinical auxiliary tools or questionnaires. To point out that in our study there are different time gaps between the first diagnosis of a psychotic episode and the last one. Also, the classification system in use was ICD 9 which is not the most updated although it is still used in the National Healthcare System in Portugal. All of the diagnosis were made using the same classification system by the different doctors responsible for clinical discharge of these patients.

Conclusions

From our data we can see that, psychiatric diagnosis, although in many cases associated with chronicity, aren't immutable. Diagnosis such as Schizophrenia or Bipolar Disorder show high values of prospective diagnostic stability (of 77% and 69%, respectively) but we have to be aware of the considerable percentage of diagnostic shift. The disease's natural evolution, new data arising and differences in the observer can be some of the causes. Nevertheless, stability percentages are very different depending on the initial diagnosis - for example, Drug Induced Psychosis with just 21% stability or non organic Psychosis with just 18% prospective stability, very different from those of Schizophrenia or Bipolar Disorder.

These diagnostic shifts can have different causes: a natural diagnosis evolution, which means, the progression from one clinical entity towards another, which raises the question if the validity of the diagnosis classification systems we use; new information related to this new admission episode but also from the period between the admissions - making very clear the need for the longitudinal evaluation of a psychiatric diagnosis; and also the differences between different clinicians establishing psychiatric diagnosis.

Classical nominal and dichotomous classifications should be questioned, diagnosis should be seen in a dimensional perspective and elements such as symptoms, evolution, outcome, familial patterns and therapeutic response should be added to the classification⁴.

A study³ with 485 adults readmitted in a Psychiatric Ward in Kerman (Iran) showed that the diagnosis was more stable for Bipolar Disorder with a 71% prospective stability and Schizophrenia with 55,9% whereas Schizoaffective Disorder should lower stability with only 28,5%. Our sample shows a similar prospective stability in Bipolar patients but a higher one for Schizophrenia and Schizoaffective Disorder. In a study very similar to ours but with outpatients, Bipolar and Schizophrenic patients were also the most stable, supposed to be associated with a more endogenous basis when compared to entities more dependent of "nurture" and the environment⁵.

Another study⁷ with 166 patients from a First Psychotic Episode Program in Hong Kong, evaluated the diagnosis at follow-up, five years after initial diagnosis. 80,7% of those patients maintained their initial diagnosis. From those who did switch diagnosis, the majorityshifted towards Schizophrenia. Bipolar Disorder showed a prospective stability of 100% and Schizophrenia 95,8%. Non Organic Psychosis, Acute and Transient Psychosis and Delusional Disorder showed lower numbers. This tendency was maintained in our sample although with a smaller stability, maybe because this cited study was restricted to a 5-year close follow-up.

Any psychiatric diagnosis can and should be questioned as new data surface. However, this should not overlook a longitudinal frame of one's history and of the disease evolution. According to Baca-Garcia⁶, diagnostic stability is greater in admitted patients than in those in outer patient appointments making this a privileged setting for diagnostic reclassification. This paper evaluates, as never before (to the extent of our knowledge) the diagnostic stability in a Psychiatric Ward in Portugal. We present a reasonable time frame and a considerable number of patients.

This paper raises questions that can lead to new work in this field: which factors influence diagnosis shift? What is the influence of that shift in the therapeutics plan used in admitted patients? What is the influence of simultaneous substance abuse on the evolution of the diagnosis?

No funding was granted for thus study. No conflict of interest to declare.