To the Editor: As stated by R. Michael Bagby, Ph.D., et al. (1), the Hamilton Depression Rating Scale was designed to measure depression severity and clinical changes in depressed patients during treatment with antidepressants (2). The validity of the Hamilton depression scale was demonstrated in this patient population (3, 4).

The review by Dr. Bagby and colleagues relevantly underlined the extended use of this scale: only 13 (18.5%) of the 70 studies published since 1979 that examined the psychometric properties of the Hamilton depression scale were carried out in depressed patients.

We suggest that this use, as shown by Dr. Bagby et al., extended the original aim of the scale and that the relevance of the Hamilton depression scale should be discussed in terms of experimental design and specific objectives (3, 4). Concerning experimental design, nondepressed patients should not be taken into account when we study the validity of the Hamilton depression scale because it has been shown that the scale is not valid in nondepressed patients (3, 4). Concerning its specific objectives, the scale should not be compared to DSM-IV criteria because the two measures have different objectives; i.e., the Hamilton depression scale assesses depression severity in depressed patients, and the DSM-IV defines a diagnosis of major depression.

Finally, we do not agree with the conclusion of Dr. Bagby et al. about the lack of validity of the Hamilton depression scale, and we suggest that the scale is a victim of its success and of inappropriate extended use. Unless significant improvement of depression assessment emerges from objective biological and morphological techniques, we do not believe it is possible to create a new instrument that would be able to assess depression from a diagnostic point of view (such as DSM-IV) and a severity point of view (such as the Hamilton depression scale) in all circumstances and in all subjects.