[Evaluation of functional remission in schizophrenic disorder. The FROGS Scale]

Functional remission is an important treatment goal in schizophrenia, as independent living and reintegration of patients into the community is the ultimate goal of any treatment. Nevertheless, assessing functional remission in schizophrenia is problematic, as it is a multifactorial entity reflecting various aspects such as symptoms severity, personal skills and sociocultural expectancies.

The purpose of this study was to create and validate a novel scale for the evaluation of functional remission in schizophrenia. Unlike previous scales, this one was built on the basis of patients with few schizophrenia symptoms. The "Functional Remission of General Schizophrenia" (FROGS) scale was developed using the expert consensus method following a MEDLINE and standard database search. Out of the 61 initially proposed, 19 items were selected as gathering the core aspects of functional remission in schizophrenia detected in the literature. The FROGS was then evaluated in 432 patients with DSM-IV criteria of schizophrenia, all of them meeting Andreasen's symptomatic remission criteria. Such an instrument should have a stable structure over time but also be able to detect improvement in functioning with time. So we have further analysed the validity of the FROGS scale, specifically assessing time stability. We re-evaluated the initial patient sample around 1.5 years after the first evaluation (mean=17.1 months ± 1.9), restricting the analyses to patients who were still being followed-up and in clinical remission (n=140).

Total score was highly reliable. Exploratory factor analysis after oblique rotation revealed that a three-factor solution was the most meaningful. On the basis of item content these three factors were labelled 'Social Functioning', 'Daily Life' and 'Treatment'. The FROGS total score can be used to measure a general construct for the evaluation of functional remission in schizophrenia. The mean FROGS total score was 75.8 (sd=10.8) at the second evaluation showing a significant improvement with time (3.8; P<0.0001 versus the first evaluation). The internal consistency/reliability of the FROGS scale was still very high (Cronbach's α=0.919). Significant improvement between the first and second evaluation were also apparent for all the individual items in the FROGS scale (P<0.01) as well as for the subscores for three extracted factors (P<0.0001). Statistically significant correlations were observed between the FROGS scale and other indices, including the Global Assessment of functioning (r=0.58; P<0.0001). These results provide further evidence of the solid psychometric properties of the FROGS scale.

The results of these two validation studies provide further evidence of the scale's utility and its solid psychometric properties. Furthermore, it is sensitive to the duration of clinical remission. Our scale may be a step towards developing a consensual definition of functional remission in schizophrenia.