Background: There is little consensus about which outcome measures to use in mental healthcare.
Aims: To investigate the relationship between the items in four staff-rated measures recommended for routine use.
Method: Correlation analysis of total scores and factor analysis using combined data from the Health of the Nation Outcome Scales (HoNOS). The Camberwell Assessment of Need Short Appraisal Schedule (CANSAS), the Threshold Assessment Grid (TAG) and the Global Assessment of Functioning (GAF) were performed. Procrustes analysis on factors and scales, and Ward's cluster analysis to group the items, were applied.
Results: The total scores of the measures were moderately correlated. The Procrustes analysis, factor analysis and cluster analysis all agreed on better coverage of the patients' problems by HoNOS and CANSAS.
Conclusions: A global severity factor accounts for 16% of the variance, and is best measured with TAG or GAF. The CANSAS and HoNOS each provide a detailed characterisation of the patient; only CANSAS provides information about met needs.