Impact of study design on the results of continuation studies of antidepressants

Association between duration of antidepressant treatment for major depressive disorder and relapse rate after discontinuation: A meta-analysis

The optimal duration of antidepressant treatment for patients with major depressive disorder to reduce the risk of relapse after discontinuation remains uncertain. Medline, Cochrane Central Register of Controlled Trials, and Embase were systematically searched for randomized controlled trials (RCTs) with a discontinuation design. A single-group summary meta-analysis was performed to calculate 6-month relapse rates after discontinuation. Meta-regression with restricted cubic splines was performed to model the non-linear relationship between treatment duration and relapse rate after discontinuation. Thirty-five RCTs were included. The relapse rate after discontinuation was approximately 34.81 % at 6 months and 45.12 % at 12 months. After controlling for covariates, the meta-analysis shows that the duration of treatment is associated with the risk of relapse after discontinuation in a non-linear curve, with a relatively higher risk of relapse observed for a duration of less than three months. There appears to be no further reduction in the risk of relapse when treatment is continued for over six months. Our results indicate the importance of at least three months of treatment to avoid the relatively high risk of relapse after discontinuation. The additional benefit of longer treatment remains to be proven.

More treatment but no less depression: The treatment-prevalence paradox

Treatments for depression have improved, and their availability has markedly increased since the 1980s. Mysteriously the general population prevalence of depression has not decreased. This "treatment-prevalence paradox" (TPP) raises fundamental questions about the diagnosis and treatment of depression. We propose and evaluate seven explanations for the TPP. First, two explanations assume that improved and more widely available treatments have reduced prevalence, but that the reduction has been offset by an increase in: 1) misdiagnosing distress as depression, yielding more "false positive" diagnoses; or 2) an actual increase in depression incidence. Second, the remaining five explanations assume prevalence has not decreased, but suggest that: 3) treatments are less efficacious and 4) less enduring than the literature suggests; 5) trial efficacy doesn't generalize to real-world settings; 6) population-level treatment impact differs for chronic-recurrent versus non-recurrent cases; and 7) treatments have some iatrogenic consequences. Any of these seven explanations could undermine treatment impact on prevalence, thereby helping to explain the TPP. Our analysis reveals that there is little evidence that incidence or prevalence have increased as a result of error or fact (Explanations 1 and 2), and strong evidence that (a) the published literature overestimates short- and long-term treatment efficacy, (b) treatments are considerably less effective as deployed in "real world" settings, and (c) treatment impact differs substantially for chronic-recurrent cases relative to non-recurrent cases. Collectively, these a-c explanations likely account for most of the TPP. Lastly, little research exists on iatrogenic effects of current treatments (Explanation 7), but further exploration is critical.

How effective are antidepressants for depression over the long term? A critical review of relapse prevention trials and the issue of withdrawal confounding

The aim of this article is to discuss the validity of relapse prevention trials and the issue of withdrawal confounding in these trials. Recommendations for long-term antidepressant treatment are based almost exclusively on discontinuation trials. In these relapse prevention trials, participants with remitted depression are randomised either to have the antidepressant abruptly discontinued and replaced by inert placebo or to continue active treatment. The drug-placebo difference in relapse rates at the end of the maintenance phase is then interpreted as a prophylactic drug effect. These trials consistently produce remarkable benefits for maintenance treatment. However, the internal validity of this trial protocol is compromised, as research has shown that abruptly stopping antidepressants can cause severe withdrawal reactions that lead to (or manifest as) depression relapses. That is, there is substantial withdrawal confounding in discontinuation trials, which renders their findings uninterpretable. It is not clear to what degree the drug-placebo separation in relapse prevention (discontinuation) trials is due to withdrawal reactions, but various estimations suggest that it is presumably the majority. A review of findings based on other methodologies, including real-world long-term effectiveness trials like STAR*D and various naturalistic cohort studies, do not indicate that antidepressants have considerable prophylactic effects. As absence of evidence does not imply evidence of absence, no definitive conclusions can be drawn from the literature. To enable a thorough risk-benefit evaluation, real-world effectiveness trials should not only focus on relapse prevention, but also assess antidepressants' long-term effects on social functioning and quality of life. Thus far, reliable long-term data on these outcome domains are lacking.

The antidepressant standoff: why it continues and how to resolve it

BACKGROUND

Antidepressant medications (ADMs) are widely used and long-term use is increasing. Given this extensive use and recommendation of ADMs in guidelines, one would expect ADMs to be universally considered effective. Surprisingly, that is not the case; fierce debate on their benefits and harms continues. This editorial seeks to understand why the controversy continues and how consensus can be achieved.

METHODS

'Position' paper. Critical analysis and synthesis of relevant literature.

RESULTS

Advocates point at ADMs impressive effect size (number needed to treat, NNT = 6-8) in acute phase treatment and continuation/maintenance ADM treatment prevention relapse/recurrence in acute phase ADM responders (NNT = 3-4). Critics point at the limited clinically significant surplus value of ADMs relative to placebo and argue that effectiveness is overstated. We identified multiple factors that fuel the controversy: certainty of evidence is low to moderate; modest efficacy on top of strong placebo effects allows critics to focus on small net efficacy and advocates on large gross efficacy; ADM withdrawal symptoms masquerade as relapse/recurrence; lack of association between ADM treatment and long-term outcome in observational databases. Similar problems affect psychological treatments as well, but less so. We recommend four approaches to resolve the controversy: (1) placebo-controlled trials with relevant long-term outcome assessments, (2) inventive analyses of observational databases, (3) patient cohort studies including effect moderators to improve personalized treatment, and (4) psychological treatments as universal first-line treatment step.

CONCLUSIONS

Given the public health significance of depression and increased long-term ADM usage, new approaches are needed to resolve the controversy.

The role of patient expectancy in placebo and nocebo effects in antidepressant trials

OBJECTIVE

To determine whether patient expectancy plays a role in observed placebo and nocebo effects in 2 clinical trials.

METHOD

Data were reanalyzed from 2 fluoxetine-discontinuation studies conducted from March 1990 to September 1992 and from May 1997 to December 2002. The 673 outpatients included were aged 18-65 years with DSM-III-R major depressive disorder (MDD), responded to 12-week duration open treatment, and were randomized to continued fluoxetine or placebo for an additional year. Participants in 1 of the included studies received a fixed dose of fluoxetine 20 mg daily, while the second study utilized flexible fluoxetine doses up to 60 mg daily. Mixed effects longitudinal models determined whether the possible randomization to placebo at 12 weeks resulted in significant depressive symptom worsening across treatments. Correlations were computed between early symptom change (weeks 1-3 of open treatment) and postrandomization symptom change (weeks 13-16 following randomization).

RESULTS

Participants continuing to receive fluoxetine and those switched to placebo had significantly higher mean Hamilton Depression Rating Scale (HDRS) scores immediately postrandomization compared to the final weeks of open treatment (P < .001 for both fluoxetine- and placebo-treated patients). In both studies, early HDRS change was significantly correlated with postrandomization HDRS change for patients receiving fluoxetine (r = -0.46, P < .001) as well as placebo (r = -0.48, P < .001).

CONCLUSIONS

The possibility of receiving placebo following 12 weeks of open fluoxetine was associated with significant symptom worsening in 2 large fluoxetine discontinuation studies. Worsening depression scores following randomization were significantly associated with the degree of improvement participants experienced during weeks 1-3 of open treatment. These results suggest that treatment changes influence patients' expectations of improvement, which, in turn, affect their depressive symptoms.

A pooled analysis of six month comparative efficacy and tolerability in four randomized clinical trials: agomelatine versus escitalopram, fluoxetine, and sertraline

OBJECTIVE

A pooled-analysis on the long-term outcome in four head-to-head studies: agomelatine versus fluoxetine, sertraline, and (twice) escitalopram. Method A meta-analytic approach was used. Hamilton Depression Rating Scale (HAM-D) scores, response and remission rates, Clinical Global Impression of Improvement (CGI-I) scores, response and remission rates, and completion rates/discontinuation rates due to adverse events were analyzed.

RESULTS

At the last post-baseline assessment on the 24-week treatment period, the final HAM-D-17 score was significantly lower in patients treated with agomelatine than in patients treated with selective serotonin reuptake inhibitors (SSRIs), as well in the total group of patients with severe depression (P = 0.014 and 0.040, respectively). HAM-D response rates at the end of 24 weeks were significantly higher in patients treated with agomelatine than in patients treated with SSRIs, as well in the total group of patients with severe depression (P = 0.031 and 0.048, respectively). HAM-D remission rates at the end of 24 weeks were numerically but not significantly higher in patients treated with agomelatine than in patients treated with SSRIs. Final CGI-I scores were significantly lower for agomelatine. CGI-I response as well as remission rates were numerically higher in patients treated with agomelatine, without statistical significance. The percentage of patients with at least one emergent adverse event leading to treatment discontinuation was 9.4% in patients treated with SSRIs and 6.6% in patients treated with agomelatine (P = 0.065).

CONCLUSION

The present pooled analysis shows that, from a clinical point of view, agomelatine is at least as efficacious as the investigated SSRIs with a trend to fewer discontinuations due to adverse events.

Patients' treatment expectancies in clinical trials of antidepressants versus psychotherapy for depression: a study using hypothetical vignettes

Previous research on patients' expectancies for improvement in clinical trials typically has been conducted after patients have already agreed to participate in a study. Depressed patients (n = 55) read 3 vignettes describing hypothetical clinical trials of antidepressant vs pill placebo, antidepressant vs antidepressant, and psychotherapy vs psychotherapy. Patients reported greater overall acceptability for psychotherapy over antidepressants. Patients had significantly greater expectancies for symptom reduction in either active comparator (medication or psychotherapy) compared with the placebo-controlled design. They also reported greater anticipated improvement and willingness to participate in the psychotherapy trial compared with either medication trial design. Patients' differential expectancies based on study design could lead to different patient populations being selected for these studies and influence clinical improvement.

Blue again: perturbational effects of antidepressants suggest monoaminergic homeostasis in major depression

Some evolutionary researchers have argued that current diagnostic criteria for major depressive disorder (MDD) may not accurately distinguish true instances of disorder from a normal, adaptive stress response. According to disorder advocates, neurochemicals like the monoamine neurotransmitters (serotonin, norepinephrine, and dopamine) are dysregulated in major depression. Monoamines are normally under homeostatic control, so the monoamine disorder hypothesis implies a breakdown in homeostatic mechanisms. In contrast, adaptationist hypotheses propose that homeostatic mechanisms are properly functioning in most patients meeting current criteria for MDD. If the homeostatic mechanisms regulating monoamines are functioning properly in these patients, then oppositional tolerance should develop with prolonged antidepressant medication (ADM) therapy. Oppositional tolerance refers to the forces that develop when a homeostatic mechanism has been subject to prolonged pharmacological perturbation that attempt to bring the system back to equilibrium. When pharmacological intervention is discontinued, the oppositional forces cause monoamine levels to overshoot their equilibrium levels. Since depressive symptoms are under monoaminergic control, this overshoot should cause a resurgence of depressive symptoms that is proportional to the perturbational effect of the ADM. We test this prediction by conducting a meta-analysis of ADM discontinuation studies. We find that the risk of relapse after ADM discontinuation is positively associated with the degree to which ADMs enhance serotonin and norepinephrine in prefrontal cortex, after controlling for covariates. The results are consistent with oppositional tolerance, and provide no evidence of malfunction in the monoaminergic regulatory mechanisms in patients meeting current diagnostic criteria for MDD. We discuss the evolutionary and clinical implications of our findings.

Homeopathic Individualized Q-Potencies versus Fluoxetine for Moderate to Severe Depression: Double-Blind, Randomized Non-Inferiority Trial

Homeopathy is a complementary and integrative medicine used in depression, The aim of this study is to investigate the non-inferiority and tolerability of individualized homeopathic medicines [Quinquagintamillesmial (Q-potencies)] in acute depression, using fluoxetine as active control. Ninety-one outpatients with moderate to severe depression were assigned to receive an individualized homeopathic medicine or fluoxetine 20 mg day(-1) (up to 40 mg day(-1)) in a prospective, randomized, double-blind double-dummy 8-week, single-center trial. Primary efficacy measure was the analysis of the mean change in the Montgomery & Åsberg Depression Rating Scale (MADRS) depression scores, using a non-inferiority test with margin of 1.45. Secondary efficacy outcomes were response and remission rates. Tolerability was assessed with the side effect rating scale of the Scandinavian Society of Psychopharmacology. Mean MADRS scores differences were not significant at the 4th (P = .654) and 8th weeks (P = .965) of treatment. Non-inferiority of homeopathy was indicated because the upper limit of the confidence interval (CI) for mean difference in MADRS change was less than the non-inferiority margin: mean differences (homeopathy-fluoxetine) were -3.04 (95% CI -6.95, 0.86) and -2.4 (95% CI -6.05, 0.77) at 4th and 8th week, respectively. There were no significant differences between the percentages of response or remission rates in both groups. Tolerability: there were no significant differences between the side effects rates, although a higher percentage of patients treated with fluoxetine reported troublesome side effects and there was a trend toward greater treatment interruption for adverse effects in the fluoxetine group. This study illustrates the feasibility of randomized controlled double-blind trials of homeopathy in depression and indicates the non-inferiority of individualized homeopathic Q-potencies as compared to fluoxetine in acute treatment of outpatients with moderate to severe depression.

Standardised rating scales in psychiatry: methodological basis, their possibilities and limitations and descriptions of important rating scales

Standardized rating scales are an important tool to improve the assessment of psychopathological symptoms in terms of validity and reliability. Especially observer-rated scales are of primary importance in this respect. Self-rating scales can give a meaningful complementary view to the findings of observer-rated scales. Besides scales covering more or less the whole spectrum of psychopathological symptoms, specialised scales focussing only on symptoms of disorders like schizophrenia or depression were developed. They are widely used, specifically for pragmatic reasons.

Meta-analysis of major depressive disorder relapse and recurrence with second-generation antidepressants

OBJECTIVE

This meta-analysis reviewed data on the efficacy and effectiveness of second-generation antidepressants for preventing major depression relapse and recurrence during continuation and maintenance phases of treatment, respectively.

METHODS

MEDLINE, EMBASE, and PsycINFO, the Cochrane Library, and International Pharmaceutical Abstracts were searched for the period of January 1980 through April 2007 for reviews, randomized controlled trials, meta-analyses, and observational studies on the topic. Two persons independently reviewed abstracts and full-text articles using a structured data abstraction form to ensure consistency in appraisal and data extraction.

RESULTS

Four comparative trials and 23 placebo-controlled trials that addressed relapse or recurrence prevention were included. Results of comparative trials have not demonstrated statistically significant differences between duloxetine and paroxetine, fluoxetine and sertraline, fluvoxamine and sertraline, and trazodone and venlafaxine. Pooled data for the class of second-generation antidepressants compared with placebo suggested a relatively large effect size that persists over time. For preventing both relapse and recurrence, the number of patients needed to treat is five (95% confidence interval of 4 to 6). Differences in the length of open-label treatment before randomization, drug type, and trial duration did not affect pooled estimates of relapse rates. Across all trials, 7% of patients randomly assigned to receive active treatment and 5% of patients randomly assigned to receive a placebo discontinued treatment because of adverse events.

CONCLUSIONS

This review demonstrates the overall benefits of continuation- and maintenance-phase treatment of major depression with second-generation antidepressants and emphasizes the need for additional studies of comparative differences among drugs.

Outcomes in major depressive disorder: the evolving concept of remission and its implications for treatment

It is increasingly recognised that major depressive disorder can be a chronic condition with many patients experiencing recurrent episodes. Remission from a depressive episode implies the absence or near absence of depressive symptoms. However, for many patients the periods between depressive episodes are not symptom free. Residual symptoms are predictors of relapse or recurrence, and may be associated with residual psychosocial impairment. In clinical studies, remission is commonly defined using a cut-off score on a rating scale for depressive symptoms, such as a score of < or = 7 on the 17-item Hamilton scale. However, there is debate about which scales and cut-offs are optimal and full-length rating scales are not widely used in clinical practice. In spite of such issues, it seems clear that a therapy should aim at the most complete remission possible. Unfortunately, recent studies have highlighted that in clinical practice usually only a low rate of remission is achieved. Although long-term treatment with antidepressants can reduce the risk of relapse or recurrence only a minority of patients in clinical practice achieve this as treatment is often prematurely stopped due to long-term side effects such as sleep disturbance, sexual dysfunctioning and weight gain. Therefore, it represents an unmet need to come up with antidepressant drugs of greater efficacy and improved tolerability as such treatments could lead to more complete remission in more patients.

Selective serotonin reuptake inhibitors for unipolar depression: a systematic review of classic long-term randomized controlled trials

BACKGROUND

Selective serotonin reuptake inhibitors are increasingly used in the long-term treatment of depression. Much of the supporting evidence about the effects of these drugs comes from discontinuation trials, a variant of randomized controlled trials whose design is problematic to interpret. We conducted a systematic review to examine the efficacy and acceptability of long-term therapy with selective serotonin reuptake inhibitors relative to placebo in the treatment of unipolar depression.

METHODS

We identified placebo-controlled randomized trials with a treatment duration of at least 6 months by searching MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials to update a recently published systematic review. Efficacy was defined in terms of response to treatment (50% improvement in depression score relative to baseline) and remission (score of 7 or below on the Hamilton rating scale for depression). Key secondary outcomes included quality of life, return to work, need for additional treatment and self-harm. Overall acceptability was defined in terms of dropouts for any reason over a course of treatment.

RESULTS

Of the 2693 records identified initially, we included 6 randomized controlled trials that met our eligibility criteria. These studies had a moderate risk of bias, had assigned a total of 1299 participants with depression to either treatment or placebo and had followed both groups for 6-8 months. We observed statistically significant improvements in response to treatment (odds ratio [OR] 1.66, 95% confidence interval [CI] 1.12-2.48), but not in remission (OR 1.46, 95% CI 0.92-2.32) or acceptability (OR 0.87, 95% CI 0.67-1.14). The effects appeared greater among patients without comorbidities.

INTERPRETATION

There is a lack of classic randomized controlled trials of serotonin reuptake inhibitors lasting more than 1 year for the treatment of depression. The results of our systematic review support current recommendations for 6-8 months of antidepressant treatment following initial recovery but provide no guidance for longer treatment.