Pharmacological interventions in dysthymia

Methodological issues raised by clinical trials on dysthymia: assessment instruments and response criteria

Dysthymia clinical trials raise several methodological issues. The validity of the concept remains a matter of concern, as does the need for specific instruments, the difficulties in assessment of change and long-term assessments. Diagnostic criteria for inclusion should be used in a polydiagnostic approach. This paper summarises the main assessment tools and diagnostic criteria used in clinical trials on dysthymia. Severity criterion for inclusion could be a Hamilton Depression Rating Scale score (HAMD-17) between 13 and 17. The main response criteria should be a decrease of at least 50% of the total score on this scale and a final score under a predetermined limit. However, other response criteria may be useful: depression self-ratings, global assessments, general psychopathology assessments, personality and defense mechanisms, quality of life, psychosocial and functional impairment, diagnostic criteria (presence or absence) and side-effect assessment.

WITHDRAWN: Drugs versus placebo for dysthymia

This review has been withdrawn due to non‐compliance with Cochrane's Commercial Sponsorship Policy.

The editorial group responsible for this previously published document have withdrawn it from publication.

The validity of animal models of predisposition to depression

Some animal models of depression, including the majority of the more recently introduced models, are better characterized as models of predisposition to depression. In the first part of this paper, we show that the basis for such a model could be either a procedure that increases the ease with which an analogue of major depression may be evoked, or a presentation analogous to dysthymia (chronic mild depression). We then consider how the concepts of predictive, face, and construct validity apply to such models. Next, we review the validity of the available models of predisposition to depression, which derive from genetics, genomics, developmental manipulations, and brain lesioning. Finally, we compare the performance of the different models, using a novel scoring system that formalizes the evaluation of animal models against each of the three sets of validation criteria.

A comparison of drugs versus placebo for the treatment of dysthymia

OBJECTIVES

Dysthymia is a depressive disorder of chronic nature but of less severity than major depression, which depressive symptoms are more or less continuous for at least two years. The aim of this review was to conduct a systematic review of all RCTs comparing drugs and placebo for dysthymia.

SEARCH STRATEGY

Electronic searches of Cochrane Library, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; reference searching; personal communication; conference abstracts; unpublished trials from the pharmaceutical industry; book chapters on the treatment of depression.

SELECTION CRITERIA

The inclusion criteria for all randomised controlled trials were that they should focus on the use of drugs versus placebo for dysthymic patients. Exclusion criteria were: non randomised, mixed major depression/ dysthymia (trials not providing separate data) and depression secondary to other disorders (e.g. substance abuse).

DATA COLLECTION AND ANALYSIS

The reviewers extracted the data independently. In order to achieve an intention-to-treat analysis, when trials failed to report it was assumed that people who died or dropped out had no improvement. Authors of relevant trials were contacted for additional and missing data. Absence of treatment response as defined by authors was the main measure of outcome used. Relative Risks (RR) and 95% confidence intervals (CI) of dichotomous data were calculated with the Random Effects Model. Where possible, number needed to treat (NNT) and number needed to harm (NNH) were estimated, taking the reciprocal of the absolute risk reduction.

MAIN RESULTS

Currently the review includes 15 trials. Similar results were obtained in terms of efficacy for different groups of drugs, such as tricyclic (TCA), selective serotonin reuptake inhibitors (SSRI), monoamine oxidase inhibitors (MAOI) and other drugs (sulpiride, amineptine, and ritanserin). The pooled RR for absence of treatment response was 0. 68 (95% CI 0.59-0.78) for TCA and the NNT was 4.3 (95% CI 3.2-6.5). SSRIs showed similar RR for this outcome: 0.64 (95% CI 0.55-0.74), the NNT being 4.7 (95% CI 3.5-6.9). Concerning MAOIs, the RR was 0. 59 (95% CI 0.48-0.71) and the NNT was 2.9 (95% CI 2.2-4.3). Other drugs (amisulpride, amineptine and ritanserin) showed similar results in terms of absence of treatment response. Using more stringent criteria for improvement - full remission - the results were unchanged. Patients treated on TCA were more likely to report adverse events, compared with placebo.

REVIEWER'S CONCLUSIONS

Drugs are effective in the treatment of dysthymia with no differences between and within class of drugs. Tricyclic antidepressants are more likely to cause adverse events and dropouts. As dysthymia is a chronic condition, there remains little information on quality of life and medium or long-term outcome.