Validation of remission criteria for schizophrenia
van Os J, Drukker M, A Campo J, Meijer J, Bak M, Delespaul P;
Commented by , 24 Nov 2006
Aim of the study
For a very long time research in schizophrenia was hampered by a lack of uniformly accepted definitions of what a response or a remission is. Only recently remission criteria for schizophrenia have been suggested by an American working group (ref. 1).
These criteria link items of rating scales such as the Positive and Negative Syndrome Scale (PANSS) to the diagnostic criteria of DSM-IV and ICD-10. The idea is that if eight selected items are at most mildly present for at least six months, a patient can be considered to be in remission.
Eight items on psychoticism, conceptual disorganisation and negative symptoms were chosen. It is very likely that the criteria will be used in many future antipsychotic drug trials. What is currently needed are studies that validate the remission concept, i.e. does the presence or absence of the criteria predict the patients' functional outcome. The current study is one of the first analysing this issue.
Method
The authors examined longitudinal data (median follow-up 1132 days) of patients with non affective psychotic disorder (n=317) in a representative catchment area (n=250000) in Holland. The data were derived from a register which included all people with schizophrenia unless they had denied participation.
The patients were classified as being in remission or not at baseline (approximately 50% in both groups). The authors examined whether change in remission status (either from being in symptomatic remission to being not in remission or vice versa) was associated with a change of patients' functional outcome in terms of unmet needs (Camberwell Assessment of Need Scale), overall functioning (Global Assessment of Functioning Scale), satisfaction with services and quality of life.
Regression models were constructed in the statistical analysis. These scales were rated at baseline and thenafter whenever there was an important change in the treatment plan, or at least in intervals of 1 to 2 years.
Results
The remission status changed in approximately a third of the patients at least once over time (in both directions – from "not in remission" to "in remission" and vice versa). In both directions, change of remission status was associated with statistically and clinically significant changes in terms of unmet needs, overall functioning and satisfaction with services.
It was also associated with a change of quality of life, but this effect was less pronounced. In a byline the authors also examined whether the addition of a depression and a suicidality item would change the overall results, but it did not. They thus concluded that the criteria are robust.
Dr Leucht's comments
It is very likely that the new remission criteria will be widely adopted in future studies. The current paper is one of the first showing that the criteria are valid in the sense that they allow to distinguish between patients with good and poor overall outcome. One of the main advantages of the new criteria is that their uniform use will allow for a better comparability of the results of different clinical trials.
A shortcoming of the current study is that the authors only had the Brief Psychiatric Rating Scale (BPRS) and not the PANSS available. Although Andreasen et al. (ref. 1) do explicitely say that remission can be measured with the BPRS, as well, the BPRS covers only 1 of 3 negative symptoms of the criteria.
It must also be pointed out to the reader that a mild presence of the 8 PANSS items is allowed but the patient is still considered to be in remission. This represents a tradeoff between stringency and being "realistic" concerning people with schizophrenia.
Remission criteria in other chronic diseases (e.g. polyarthritits) do also not require a complete absence of symptoms. Nevertheless, the reader must be aware that remission of schizophrenia does not mean a complete absence of symptoms to be able to interprete such data correctly. One of the next steps is the development of recovery criteria for schizophrenia.
References
1. Andreasen NC, Carpenter WT Jr, Kane JM, Lasser RA, Marder SR, Weinberger DR. Remission in schizophrenia: proposed criteria and rationale for consensus. American Journal of Psychiatry 2005; 162 (3); 441-449