Reliability of a longitudinal sequence of scale ratings.

Abstract

Longitudinal studies are permeating clinical trials in psychiatry. Additionally, in the same field, rating scales are frequently used to evaluate the status of the patients and the efficacy of new therapeutic procedures. There- fore, it is of utmost importance to study the psychometric properties of these instruments within a longitudinal framework. In the area of depression, the Hamilton Depression Rating Scale (HAMD) is regularly used for antidepres- sant treatment evaluation. However, the use of HAMD has not been exempted from criticism what has lead to the development of new scales that are ex- pected to be more sensitive for change, such as the Montgomery-°Asberg De- pression Rating Scale (MADRS). In general, the reliability of these scales has been extensively studied by using classical methods for reliability estimation, developed for specifically designed reliability studies. Unfortunately, the set- tings customarily considered in these reliability studies are usually far from the practical conditions in which these scales are applied in clinical trials and practice. In the present paper we assess the reliability of these instruments in a more realistic scenario thereby using longitudinal data coming from clinical studies. Nowadays, newly developed methodology based on an extended con- cept of reliability, allow us to use longitudinal data for reliability estimation.....