Course And Outcome

Although the course and outcome of schizophrenia have been the subject of a great number of studies throughout this century, the issue still remains a topic of considerable debate.

There have been many attempts to classify the courses of schizophrenia, but there is no universally accepted classification in this field. In a recent review, Marengo [73] compares different prototypes that have been proposed over the last 50 years. The author highlights differences in the number of courses described, in the structure of course categories, in the relative emphasis on syndrome character or severity (e.g. severe forms, intermediate forms, etc.) versus syndrome change (e.g. persistent, progressive, etc.), and in documenting specific course features such as illness onset, illness outcome and type of symptoms.

Earlier prototypes listed seven [74], ten [75] and five [76] course categories. Muller's categories [74] described onset, post-onset course and outcome, while Arnold's [75] and Ey's [76] focused on post-onset course and outcome. More recent prototypes identify eight [77, 78] and 12 [61] course categories. Bleuler's and Ciompi's [77, 78] categories are similar and focus on onset, post-onset course and outcome. Huber's [61] classification is more complex, in particular because it is represented in terms of a multilevel typology that includes references to psychotic symptoms, residual symptoms and social impairment.

For future studies on the course of schizophrenia, Marengo [73] recommends that a minimum set of parameters should be documented, including: (a) the rate of syndrome onset; (b) post-onset patterns of psychotic and residual symptoms; (c) post-onset patterns of social, work, and self-care activities; and (d) outcome. For both parameters (b) and (c), Marengo proposes nine patterns.

The course specifiers that are proposed in the current classifications of mental disorders are listed in detail below.

The outcome of schizophrenia has been investigated in many studies throughout the century. The results of these studies remain contradictory.

In 1994, Hegarty et al [79] identified a total of 821 studies on the course and outcome of schizophrenia conducted worldwide between 1895 and 1992. Most of these studies did not, however, satisfy at least minimal methodological standards. 320 studies met the inclusion criteria for a meta-analysis. The results showed that only 40.2% of patients were considered improved after follow-ups averaging 5.6 years. Diagnostic criteria have had a consistent and predictable impact on outcome before and during the era of modern biomedical treatment. As was to be expected, outcome was significantly better when patients were diagnosed according to systems with broad criteria (46.5% were improved) rather than narrow criteria (27.3% were improved), in particular because of the introduction, in the latter, of a duration-of-illness criterion.

The results of several reviews of North American and European long-term follow-up studies of schizophrenia [80, 81] have found wide heterogeneity in long-term outcome. Much of the variance in the results from these studies could be linked to sample characteristics, such as broad versus narrow diagnostic criteria and inclusion versus exclusion of dimensions of chronicity in the definition of the disorder.

In 1998, Riecher-Rossler and Rossler [82] discussed the methodological limitations of previous studies and reviewed in detail a number of studies that satisfied certain methodological standards. In a third step, the authors selected and discussed the results of those studies that they considered as methodologically sound, in that they were prospective, standardized and direct investigations of a representative, catchment-area-based sample of first-admitted or first-contact patients diagnosed directly and according to a standardized diagnostic system.

According to Riecher-Rossler and Rossler, there were only three studies that met these criteria: the Buckinghamshire Study [83], the DOS study [64] and the ABC study [62,63]. Further course (after first admission) was assessed based on treatment parameters, symptomatology, and different levels of psychological impairment and social disability. Duration of follow-up was 2 years [64], 5 years [83], and 10 years [62]. About one third of the patients in the three studies were never rehospitalized during these years. Almost all received medication during this time.

In the Buckinghamshire study, 22% of the patients remained symptom-free over the 5 years following first admission, 35% developed further discrete episodes but were free of symptoms between episodes, and 43% showed persistent florid symptoms. In the DOS study, 50% of the patients had only one episode, 31% two or more episodes followed by remission, and only 16% persistent symptomatology without remission.

In the DOS study, less than one third of the patients suffered more or less severe impairment during the observation period, while more than one third of them showed no impairment in social functioning during at least three-quarters of this period. In the Buckinghamshire study, 45% of the patients showed only minimal, 43% mild to moderate, and 12% severe impairment during the observation period. Finally, in the ABC study, it was shown that impairment often occurred already in the preclinical course of the disorder.

In the conclusion to their review, Riecher-Rossler and Rossler state that the course of schizophrenia may in fact be less unfavourable than implied by other studies in the past. It certainly does not appear systematically to show a progressive deterioration as stated by Kraepelin.

There are, however, other recent studies which show that schizophrenia still is a chronic and frequently disabling disease, and that its outcome is generally worse than that of other functional mental illnesses [80]. In a longitudinal study, Harrow et al [84] compared the course and outcome of schizophrenia versus other psychotic disorders. According to the results of this study, the majority of patients with schizophrenia did not show complete and consistent remission over the long term and experienced significantly poorer functioning than patients with other psychotic disorders at each of three successive follow-ups over 7.5 years. In a study on the natural course of schizophrenic disorders, Wiersma et al [85] present results on the 15-year natural course of the disorder. The study revealed that two-thirds of the subjects had at least one relapse and that after each relapse one of six subjects did not remit from the episode. In addition, one of ten committed suicide.

On the whole, follow-up studies of the course of schizophrenia indicate that there may be very different types of course, ranging from complete cure to severe disabling chronic forms. Some patients experience only one episode of illness, others have several episodes, and still others suffer from chronic symptoms.

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