I was very interested to read the article by Salvi et al (Reference Salvi, Leese and Slade2005) on choosing the measure for mental health outcome assessments. Readers might be interested in a comparison of the Camberwell Assessment of Need Short Appraisal Schedule (CANSAS; Reference Phelan, Slade and ThornicroftPhelan et al, 1995) and Health of the Nation Outcome Scale (HoNOS; Reference Wing, Beevor and CurtisWing et al, 1998) scores. One thousand pairs of HoNOS and CANSAS scores were recorded by four trainees and myself. Figure 1 shows the means with standard errors of the HoNOS values associated with each CANSAS score.

Fig. 1 Comparison of 1000 pairs of CANSAS and HoNOS scores. Bars represent two standard errors above and below the mean. CANSAS, Camberwell Assessment of Need Short Appraisal Schedule; HoNOS, Health of the Nation Outcome Scale.

The higher CANSAS scores (13-22) were not encountered very often and accounted for only 3.5% of scores. The large standard errors are because some of the CANSAS scores occurred infrequently.

HoNOS and CANSAS scores are related in the lower CANSAS range of 1-8, the most common range, accounting for 79% of the scores. Up to a CANSAS score of 12 (n=955) there is a reasonably close correlation with the HoNOS scores. The Spearman coefficient is 0.564, indicating that the correlation is significant at the 0.01 level (two-tailed).

The use of CANSAS is becoming established in Lothian mental health services. CANSAS is very useful as a needs assessment tool for individual patients. Its face validity as an outcome measure is not as good as that of the Threshold Assessment Grid (Reference Slade, Powell and RosenSlade et al, 2000), Global Assessment of Functioning (Reference Jones, Thornicroft and CoffeyJones et al, 1995) or HoNOS. This correlation exercise confirms that it can be used as an outcome measure with reasonable validity. It is useful in terms of consultant appraisal discussions, evaluation of workload of community and ward mental health teams and local and regional assessment of outcomes in different patient groups. Given the above correlation, benchmarking is also possible with other services, especially in England, where HoNOS is established. The conclusions of Salvi et al (Reference Salvi, Leese and Slade2005) in the last paragraph of their article are absolutely valid.

Given the great difficulty in implementing and coordinating any single outcome assessment, I hope that the above comparison of CANSAS and HoNOS scores, in combination with the results of Salvi et al (Reference Salvi, Leese and Slade2005), will assist those running mental health services.