Does inclusion of a placebo arm influence response to active antidepressant treatment in randomized controlled trials? Results from pooled and meta-analyses

Are antidepressants useful in the treatment of minor depression: a critical update of the current literature

PURPOSE OF REVIEW

In minor depression, the number, severity or duration of symptoms are insufficient to diagnose a major depression or dysthymia. Nevertheless, minor depression is a prevalent disorder associated with functional disability, impairment of quality of life, and intense healthcare use. The aim of this article is to discuss the evidence for the effectiveness of antidepressants in patients with minor depression taking into account a recent meta-analysis and further clinical trials as well as methodological problems associated with the common approach to deducing the clinical significance of therapeutic effects of antidepressants from placebo-verum differences in randomized clinical trials (RCTs).

RECENT FINDINGS

A recent meta-analysis, comprising six RCTs, and two newer studies do not provide evidence for the efficacy of antidepressants in patients with minor depression, but do not have the power and the methodological quality to exclude efficacy. Possible risks of underestimating the clinical significance of antidepressants based on RCT data are discussed.

SUMMARY

For minor depression, unspecific support like active monitoring, unspecific group counselling or internet-based guided self-help activities are reasonable treatment options. Antidepressants can be considered in special cases with, for example, suicidality, previous suicide attempts, family history of affective disorders or previous major depressive episodes.

Is switching antidepressants following early nonresponse more beneficial in acute-phase treatment of depression?: a randomized open-label trial

RATIONALE

Treatment guidelines for major depressive disorder (MDD) recommend a continuous use of antidepressants for several weeks, while recent meta-analyses indicate that antidepressant efficacy starts to appear within 2 weeks and early treatment nonresponse is a predictor of subsequent nonresponse.

OBJECTIVES

We prospectively compared 8-week outcomes between switching antidepressants and maintaining the same antidepressant in early nonresponders, to generate a hypothesis on possible benefits of early switching strategy.

METHOD

Patients with MDD without any treatment history for the current episode were included. When subjects failed to show an early response (i.e., ≥20% improvement in the Montgomery-Åsberg Depression Rating Scale (MADRS)) to the initial treatment with sertraline 50mg at week 2, they were randomly divided into two groups; in the Continuing group, sertraline was titrated at 50-100mg, whereas sertraline was switched to paroxetine 20-40 mg in the Switching group. A primary outcome measure was a response rate (i.e., ≥50% improvement in the MADRS) at week 8.

RESULTS

Among 132 subjects, 41 subjects showed early nonresponse. The Switching group (n=20) showed a higher rate of responders than the Continuing group (n=21) (75% vs. 19%: p=0.002). Further, the Switching group was also superior in the rate of remitters (total score of ≤10 in the MADRS) (60% vs. 14%: p=0.004) and continuous changes in the MADRS (19.0 vs. 7.5: p<0.001).

CONCLUSIONS

Our preliminary findings suggest that patients with MDD who fail to show early response to an initial antidepressant may derive benefits from the early switching antidepressants in the acute-phase treatment of depression.

Symptomatic and functional improvement in employed depressed patients: a double-blind clinical trial of desvenlafaxine versus placebo

OBJECTIVE

This is the first study to assess the efficacy of desvenlafaxine (administered as desvenlafaxine succinate) for improving depressive symptoms and functioning exclusively in employed patients with major depressive disorder (MDD).

METHODS

Gainfully employed (≥20 h/wk) male and female outpatients with MDD were randomly assigned (2:1 ratio) to 12 weeks of double-blind treatment with desvenlafaxine 50 mg/d or placebo. Analysis of covariance was used to compare differences in week 12 adjusted mean changes from baseline on the 17-item Hamilton Depression Rating Scale (HAM-D₁₇) (primary outcome) and Sheehan Disability Scale (SDS) (key secondary outcome) in the intent-to-treat (ITT) population. A predefined, modified ITT population (ie, those in the ITT population with baseline HAM-D₁₇ ≥20) was also analyzed. Tolerability was assessed by recording adverse events and change on the Arizona Sexual Experience Scale.

RESULTS

Baseline HAM-D₁₇ scores for desvenlafaxine (n = 285) and placebo (n = 142) were 22.0 and 21.8, whereas baseline SDS scores were 19.8 and 20.4. Adjusted mean differences between desvenlafaxine and placebo were 2.1 (95% confidence interval [CI], 0.78-3.46; P = 0.002) on the HAM-D₁₇ and 1.3 (95% CI, -0.09 to 2.76; P = 0.067) on the SDS. For the modified ITT sample, desvenlafaxine (n = 208) and placebo (n = 102), baseline HAM-D₁₇ scores were 23.8 and 23.9; the SDS baseline scores were 20.1 and 20.8. Mean differences were 2.6 (95% CI, 0.93-4.22; P = 0.002) on the HAM-D₁₇ and 2.1 (95% CI, 0.36-3.76; P = 0.017) on the SDS. Adverse events and Arizona Sexual Experience Scale scores were comparable between groups.

CONCLUSIONS

Desvenlafaxine 50 mg/d was efficacious for treating MDD in gainfully employed adults. Between-group differences on the SDS narrowly missed statistical significance in the ITT population alone, but the totality of data suggests functional improvements with active treatment.

Recent developments in improving signal detection and reducing placebo response in psychiatric clinical trials

Recent (2007-2010) empirical and theoretical literature on associations of trial design features with signal detection and placebo response were investigated, along with data and analytic considerations. Trials with greater percentages of patients randomized to placebo had larger average drug-placebo differences in two comprehensive meta-analyses (MDD and Schizophrenia). Excluding patients with large responses during double-blind placebo lead-ins resulted in small increases in drug-placebo differences. Core factor subscales of the HAMD yielded larger drug-placebo differences than the HAMD total score. Direct likelihood-based (MMRM) and similar analyses provided better control of false positive and false negative results than LOCF and BOCF. Theoretical considerations suggested that the number of sites and number of countries can influence power, depending on the correlation structure in the data and on how sites and countries are chosen. Use of centralized ratings reduced placebo response and improved drug-placebo differences. However, the number of comparisons was too small to draw conclusions. Use of patient ratings and reducing the number of study visits reduced placebo response, but their effects on signal detection were unclear. Practical experience with novel designs such as the sequential parallel approach hold promise for improvements in signal detection. Given the complexities of signal detection and placebo response, no single strategy is likely to fully solve the problem and combinations of approaches may be most useful. Utilizing appropriate analytic techniques and randomizing an adequate fraction of patients to placebo are perhaps the most broadly applicable approaches.

Introduction to placebo effects in medicine: mechanisms and clinical implications

The field of placebo research has made considerable progress in the last years and it has become a major focus of interest. We know now that the placebo effect is a real neurobiological phenomenon and that the brain's 'inner pharmacy' is a critical determinant for the occurrence of psychobiological and behavioural changes relevant to healing processes and well-being. However, harnessing the advantages of placebo effects in healthcare is still a challenge. The first part of the theme issue summarizes and discusses the various kinds of placebo mechanisms across medical fields, thereby not only focusing on two main explanatory models-expectation and conditioning theory-but also taking into account empathy and social learning, emotion and motivation, spirituality and the healing ritual. The second part of the issue focuses on questions related to transferring knowledge from placebo research into clinical practice and discusses implications for the design and interpretation of clinical trials, for the therapeutic settings in daily patient care, and for future translational placebo research.

The placebo response in clinical trials: more questions than answers

Meta-analyses and re-analyses of trial data have not been able to answer some of the essential questions that would allow prediction of placebo responses in clinical trials. We will confront these questions with current empirical evidence. The most important question asks whether the placebo response rates in the drug arm and in the placebo arm are equal. This 'additive model' is a general assumption in almost all placebo-controlled drug trials but has rarely been tested. Secondly, we would like to address whether the placebo response is a function of the likelihood of receiving drug/placebo. Evidence suggests that the number of study arms in a trial may determine the size of the placebo and the drug response. Thirdly, we ask what the size of the placebo response is in 'comparator' studies with a direct comparison of a (novel) drug against another drug. Meta-analytic and experimental evidence suggests that comparator studies may produce higher placebo response rates when compared with placebo-controlled trials. Finally, we address the placebo response rate outside the laboratory and outside of trials in clinical routine. This question poses a serious challenge whether the drug response in trials can be taken as evidence of drug effects in clinical routine.

Dissection of the factors driving the placebo effect in hypnotic treatment of depressed insomniacs

OBJECTIVES

Our prior work has shown that there is improvement in self-reported sleep in persons receiving placebo in hypnotic clinical trials. We examined the components of the "placebo response" in a hypnotic clinical trial.

METHODS

This was an exploratory analysis of a randomized, double-blind clinical trial of eszopiclone versus placebo in the treatment of persons with depression and insomnia who were also receiving fluoxetine at a clinic of a teaching hospital. Sixty adults with both depression and insomnia symptoms, who were free of significant primary sleep disorders, received open-label fluoxetine for 9weeks. Patients were further randomized 1:1 to receive either masked eszopiclone 3mg or placebo at bedtime after the first week of fluoxetine. We examined the respective contributions of three factors associated with the "placebo effect": (1) regression to the mean, (2) expectancy, and (3) social desirability.

RESULTS

There was evidence for regression to the mean for the continuous measurement of the Insomnia Severity Index (ISI) and the Hamilton Depression Rating Scale. There was evidence for expectancy in self-reported Wake After Sleep Onset, continuous measurement of ISI, and dichotomous remission/non-remitter measurement of ISI. There was evidence of social desirability affecting self-reported Total Sleep Time.

CONCLUSIONS

Factors that have been associated with the "placebo effect" are operating in hypnotic clinical trials. However, the role of each factor differs depending upon which self-reported variable is being considered. The findings have implications for clinical trial design in insomnia.

Usual and unusual care: existing practice control groups in randomized controlled trials of behavioral interventions

OBJECTIVE

To evaluate the use of existing practice control groups in randomized controlled trials of behavioral interventions and the role of extrinsic health care services in the design and conduct of behavioral trials.

METHOD

Selective qualitative review.

RESULTS

Extrinsic health care services, also known as nonstudy care, have important but under-recognized effects on the design and conduct of behavioral trials. Usual care, treatment-as-usual, standard of care, and other existing practice control groups pose a variety of methodological and ethical challenges, but they play a vital role in behavioral intervention research.

CONCLUSIONS

This review highlights the need for a scientific consensus statement on control groups in behavioral trials.