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A model for handling missing items on two depression rating scales

Gale, T.a,b,c; Hawley, C.a,b

International Clinical Psychopharmacology:
Research Papers
Abstract

A problem in clinical trials for antidepressants is that patient rating scales are not always completed properly. If one or more items are missing, a patient evaluation may be prevented from contributing towards an efficacy analysis. This can be very wasteful, particularly if data are missing at a baseline evaluation. In this study, we present a novel approach to estimating missing item scores on both the Montgomery-Åsberg Depression Rating Scale and the Beck Depression Inventory. Our approach works on the assumption that patient response is non-uniform across items. By capturing the average between-item variation, we have developed a set of weights for each scale which can be used to predict missing item scores with high levels of accuracy. These weights were tested on several sets of patient data when one item was missing. The proposed weights are stable and will be of practical use to researchers in the field of Major Depression.

Author Information

The Hertfordshire Neurosciences Research Group (HNRG), aDepartment of Psychiatry, QEII Hospital, Welwyn Garden City and Departments of bPsychology and cComputer Science, University of Hertfordshire, Hatfield, UK

Correspondence to T.M. Gale, Department of Psychology, University of Hertfordshire AL7 4HQ, UK; Tel: +44 (0)1707 365383; fax: +44 (0)1707 365168; e-mail: t.gale@herts.ac.uk

Received 24 October 2000; accepted 30 January 2001

© 2001 Lippincott Williams & Wilkins, Inc.