The reliability of the Psychiatric Impairment Scale (PIRS) in valuing psychological impairment
This study examines the validity of valuations made using the descriptors in the subscales of the Psychiatric Impairment Scale (PIRS). Estimates of the item valuations on a 0-100 scale made by a group of psychiatrists trained in the use of the PIRS and a comparative group of patients with psychiatric disorders were compared. The results are contrasted with impairment ratings resulting from the use of the prescribed valuations of the descriptors. There was good agreement between the groups on the valuation of classes 1 and 2, but a substantial loss of discriminative ability for classes 3, 4 and 5. Valuations of the degree of disability for each class were, in all cases, much larger than the value obtained using the standard scoring system, suggesting that the level of impairment measured by the PIRS is undervalued. Questions are also raised regarding the reliability of the PIRS in use.