L'échelle de dépression de Hamilton (HAM-D₁₇) à 17 éléments sert depuis quatre décennies, en recherche clinique, comme «étalon-or» afin d'évaluer la gravité de la dépression et la réponse au traitement. L'utilité clinique de l'échelle HAM-D₁₇ est en partie entravée par le temps nécessaire pour réaliser l'entrevue et par les préoccupations que soulève le manque de fiabilité entre les évaluateurs. Plusieurs groupes ont mis au point des versions abrégées de l'échelle HAM-D₁₇ pour la pratique clinique. En dépit de recherches poussées qui mettent en évidence l'importance de réaliser une rémission complète pour réduire au minimum le risque de rechute et de récidive, ces questionnaires abrégés n'ont pas été validés pour la tâche qui consiste à distinguer la rémission de la réponse. Une version abrégée de l'évaluation HAM-D₁₇ et des résultats limites dans le cas de la rémission complète constitueraient un outil utile que les médecins pourraient facilement employer en pratique clinique. En nous fondant sur les réponses d'un échantillon de 292 patients aux prises avec une dépression majeure qui ont reçu le traitement clinique normalisé à un hôpital de soins tertiaires affilié à une université (Clinique de la dépression, Centre de toxicomanie et de santé mentale, Toronto (Ontario)), nous avons dérivé une version abrégée de l'évaluation HAM-D. Nous avons défini les sept éléments les plus fréquents et les plus sensibles aux changements produits par le traitement et nous avons donné à notre sous-échelle l'appellation «HAM-D₇ de Toronto». On a constaté qu'un résultat de 3 ou moins sur l'échelle HAM-D₇ de Toronto correspondait à une rémission complète selon la définition HAM-D à 17 éléments (c.-à-d. un résultat de 7 ou moins).

The goal of antidepressant treatment is sustained and full remission of depressive symptoms to prevent relapse and recurrence, with a return to previous levels of occupational and social functioning. Failure to achieve full remission is associated with an increased risk of relapse and recurrence, higher rates of chronicity, readmission to hospital, with high service utilization and a reduced quality of life. Therefore, distinguishing response (i.e., symptomatic improvement with residual or subsyndromal depressive symptoms) from remission (i.e., virtually full symptom elimination) has important clinical significance and requires the systematic monitoring of the presence and severity of depressive symptoms.

The Hamilton Depression Rating Scale (HAM-D) was originally published in 1960.^3,4 Although widely used by psychiatric researchers, especially in clinical trials, this and other clinician rating scales are not widely used in clinical practice. The time required to administer the questionnaire is thought to be one deterrent to its use. To obtain more clinically useful measures of depression severity and response to treatment, several groups have developed brief versions of the HAM-D.^5,6,7 However, despite extensive research highlighting the importance of achieving full remission, it is not known whether these shortened questionnaires provide a means of distinguishing between remission and response. A brief HAM-D with cut-off scores for full remission would be a useful tool that physicians could readily employ in clinical practice.

The treatment protocol for the clinical database requires patients to be treated and followed for at least 14 weeks but not more than 26 weeks.

Table 1 outlines the frequency of occurrence at baseline and the magnitude of change at the end of treatment for each of the 17 HAM-D items for the patients in the database. Depressed mood, guilt, suicide, insomnia (middle), difficulty with work and interests, psychic and somatic anxiety, as well as general somatic symptoms were reported by more than 70% of patients. Loss of insight and weight change were infrequent. With the exception of item 5 (middle insomnia), these items were also those that were most sensitive to change with treatment, exhibiting change scores (calculated as effect sizes [Cohen's d]) between 0.83 and 1.84. Insomnia was relatively less sensitive to change with treatment and was therefore not included in the final Toronto HAM-D₇.

The items that were reported most frequently and were the most sensitive to change (i.e., 1, 2, 3, 7, 10, 11 and 13) were included in the Toronto HAM-D₇ (Table 2). These items overlap considerably with those included in previous unidimensional subscales, with depressed mood, work and interests, guilt and psychic anxiety being included in all subscales. The items in the HAM-D short forms were tested for reliability and internal consistency and found to be comparable across the various shortened versions and the full HAM-D₁₇.

The briefer unidimensional versions of the HAM-D₁₇, which assess “core depressive symptoms” commonly reported in clinical practice (e.g., the Bech Melancholia Scale, Maier and Phillip Severity Subscale and the Gibbons Global Depression Severity Scale)^5,6,7 share considerable symptom overlap in that they all include items 1, 2, 7 and 10. The items in the Toronto HAM-D₇, selected on the basis of their frequency of occurrence at baseline and their sensitivity to change with treatment, also included items 1, 2, 7 and 10.

These brief scales have been shown to correlate with the HAM-D₁₇ assessment of both severity of symptoms and sensitivity to change over time. A study of 164 depressed outpatients with and without atypical features demonstrated that the Bech HAM-D₆ was as sensitive to symptom changes as the 17-, 21- and 24-item versions of the scale.¹¹ Furthermore, the different versions of the HAM-D were strongly correlated with each other at baseline and endpoint in both depression subtypes. It was concluded that the 6-item version of the HAM-D allowed the assessment of severity of depression with comparable sensitivity to the standard and more elaborate versions of the same scale. Hooper and Bakish¹² compared the sensitivity of the HAM-D₆ with the HAM-D₁₇ and the MADRS in a retrospective analysis of 4 clinical trials (3 double-blinded, 1 open study) comprising 143 outpatients receiving treatment for major depressive disorder, with or without melancholia and/or dysthymic disorder. The briefer version strongly correlated with the longer version at baseline and termination. The HAM-D₆, HAM-D₁₇, and MADRS demonstrated equal sensitivity to change over the course of treatment, both in the full sample and in the dysthymic and melancholic subgroups. The ability of the shorter version to show comparable results supports the assertion that the HAM-D₆ measures “core” features of depression.

Faries et al¹³ conducted 2 meta-analyses (n = 2899) to compare the sensitivity of the multidimensional HAM-D₁₇ with the unidimensional briefer scales (Bech,⁵ Maier⁷ and Gibbons⁶) for detecting treatment differences. In both meta-analyses, the unidimensional core subscales outperformed the HAM-D₁₇ at detecting treatment differences. With the improved responsiveness and increased effect size, studies based on these subscales would require one-third fewer subjects to detect drug treatment differences. The HAM-D₆ appears to be as (or more) sensitive to change during treatment as the HAM-D₁₇ and the MADRS.

One potential limitation of the shorter form is that, statistically, the presence of fewer items typically results in lower reliability. However, our data indicate that the shorter forms have comparable reliability estimates to the HAM-D₁₇. In addition, all of these shortened versions have been extracted from the same parent HAM-D₁₇. Development of the original scale was guided by clinical experience and logic rather than by empirical testing and re-evaluation.⁶ It is confounded by extraneous items that do not reflect severity of depression; it is vulnerable to the influence of antidepressant side effects, and the clinical value of the total score is not clear.^6,12 Moreover, the HAM-D₇ was not validated in patients with known concurrent medical disorders. It is well established that many people with depression in primary care settings present with multiple medical conditions and somatic complaints. The HAM-D₇ includes 2 items that assess somatic symptoms (somatic anxiety, energy). It behooves the clinician to ascertain if somatic symptoms are part of a confluence of depressive symptoms or due to a general medical condition; this scale does not replace everyday clinical decision making.

The question is, does a shortened version of a flawed scale have clinical utility? A prospectively designed study to investigate factors that are indicative of the severity of depression and are sensitive to change with antidepressant therapy would be ideal. A prospective study to validate the Toronto HAM-D₇ in general practice is planned.

The clinical utility of the shorter version is increased by the determination that a score of approximately 3 or less is comparable to a HAM-D₁₇ score of less than 8, which is considered a full remission. A cut-off score for “response” was not derived, because it is not considered an acceptable endpoint in clinical practice. A caution is that the cut-off scores derived in this study were based on discriminant function analysis, which employs an algorithm that maximizes a balance between sensitivity (in this instance the presence of remission) and specificity (the absence of remission). Different cut-off scores might be applied if the clinician is more concerned about misidentifying a patient who is not in remission as being in remission (undertreating) at the expense of misidentifying a patient who is in remission as not (overtreating).