Use of quantitative rating scales to assess outcome in schizophrenia prevention studies

To present a summary of quantitative scales relevant to schizophrenia prevention studies.

Fifteen scales were reviewed and summarised in terms of structure, domains assessed, previous use and psychometric properties. Instruments of symptom measurement, role functioning and global functioning were considered, along with multidimensional instruments and other scales of potential interest to research in schizophrenia prevention.

No scales of potential value in measuring premorbid risk for schizophrenia have been sufficiently tested for reliability and validity in the context of primary prevention of schizophrenia. The absence of a sufficiently sensitive and specific means for identifying those at high risk of schizophrenia before the onset of psychosis is a major barrier to valid measurement of the outcome of attempts at primary prevention. However, there have been advances in the development of instruments relevant to the goals of secondary and tertiary prevention. Most studies use instruments developed for patients with established psychoses and have applied them to early psychosis groups with some success, although possible 'floor' effects may confound measurement in the 'prodromal' period.