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

Objective: To present a summary of quantitative scales relevant to schizoph renia prevention studies. Method: 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 considere d, along with multidimensional instruments and other scales of potential in terest to research in schizophrenia prevention. Results and conclusions: No scales of potential value in measuring premorbi d 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 hi gh risk of schizophrenia before the onset of psychosis is a major barrier t o valid measurement of the outcome of attempts at primary prevention. Howev er, there have been advances in the development of instruments relevant to the goals of secondary and tertiary prevention. Most studies use instrument s developed for patients with established psychoses and have applied them t o early psychosis groups with some success, although possible 'floor' effec ts may confound measurement in the 'prodromal' period.