The Psychiatric Impairment Rating Scale: Is it a valid measure?

Abstract

The Psychiatric Impairment Rating Scale (PIRS) was introduced as part of the Workcover legislation in NSW and has since been adopted in other States. There has been significant criticism of its validity and structure, but no supporting research. This study was undertaken to examine the validity of the use of the PIRS to assess psychiatric impairment. This study assesses the concurrent validity of the PIRS by comparing it with the Comcare and Social Security scales and the Health of the Nation Outcome Scale, together with two self-report measures. It also examines the relationship between the PIRS subscales. A high level of ordinal concordance was demonstrated between all scales although the ratings obtained had major systematic variations between scales in both level and distribution. The scoring technique in the PIRS transforms normally distributed scores to a skewed distribution with a preponderance of low scores. The PIRS is a valid scale for ordering the severity of psychological disability but it measures disability rather than impairment. The form of scoring does not provide a proportionate or statistically meaningful measure.

Acknowledgements

I would like to thank Dr Peter Caputi and Ms Nicola Ronan of the Department of Psychology, University of Wollongong for their valuable help and advice, without which this project could not have been completed.