Placebo: misunderstandings and prejudices

Placebo response in trichotillomania

Trichotillomania is a functionally impairing, often overlooked disorder with no Food and Drug Administration-approved medications indicated for its treatment. The ability of clinical trials to detect the beneficial effects of pharmacologic treatment in trichotillomania has been hampered by the high placebo response rate. Very little is known about baseline demographic and clinical characteristics that may be predictive of placebo response in such patients. Overall, 104 participants assigned to placebo were pooled from five double-blind trials conducted at three sites in the USA and Canada. Participants were classified as placebo responders or nonresponders on the basis of a cutoff of a 35% reduction in symptom severity on the Massachusetts General Hospital Hair Pulling Scale. Baseline group differences were characterized using t-tests and equivalent nonparametric tests as appropriate. Thirty-one percent of individuals assigned to placebo treatment showed a significant clinical response to placebo. Placebo responders (n=32) and nonresponders (n=72) did not differ significantly on any demographic or clinical variable. Predictors of placebo response for trichotillomania remain elusive and do not appear to be similar to those reported for other mental health disorders.

The placebo effect and its clinical associations in gambling disorder

BACKGROUND

Although gambling disorder is prevalent and functionally impairing, no FDA-approved medications exist for its treatment. The ability of clinical trials to detect the benefits of active treatment has been hindered by an unusually high placebo response. Virtually nothing is known about baseline clinical characteristics that might predict placebo response in those with gambling disorder.

METHODS

Participants (N = 152) assigned to placebo were pooled from multiple double-blind trials of gambling disorder. Participants were classified as placebo responders or non-responders based on a cut-off of 35% reduction in symptom severity on the Gambling Symptom Assessment Scale. Baseline group differences were characterized using t tests and equivalent non-parametric tests as appropriate.

RESULTS

Fifty-one percent of individuals assigned to placebo showed a significant clinical response. Compared with non-responders, placebo responders remained in treatment for significantly longer, were more likely to report "enjoyment" as a trigger for gambling, and were less likely to state that "boredom" or "loneliness" triggered their gambling. Placebo responders and non-responders did not differ significantly in age, sex, age at symptom onset, baseline symptom severity, comorbidities, or likelihood of having received a previous treatment.

CONCLUSIONS

Predictors of placebo response for gambling disorder appear markedly different from those reported for other mental illnesses.

The placebo response of injectable GLP-1 receptor agonists vs. oral DPP-4 inhibitors and SGLT-2 inhibitors: a systematic review and meta-analysis

AIMS

The size of the placebo response in type 2 diabetes (T2DM) treatment and its relation to the route of drug administration have not been systematically reviewed. We aimed to determine weight loss, change in HbA1c and incidence of adverse events after treatment with injectable placebo GLP-1 receptor agonist (GLP-1ra), compared with oral placebo DPP-4 inhibitor (DPP-4i) and placebo SGLT-2 inhibitor (SGLT-2i).

METHODS

PubMed, EMBASE and Central were searched up to September 2014 for randomized placebo controlled trials investigating GLP-1ra, DPP-4i or SGLT2-i. Data on placebo groups were extracted and pooled using a generic inverse variance random effects model.

RESULTS

Sixty-seven trials were included, involving 2522, 5290 and 2028 patients randomized to placebo GLP-1ra, placebo DPP-4i and placebo SGLT-2i, respectively. Body weight decreased by -0.67 kg (95% CI -1.03, -0.31) after treatment with placebo GLP-1ra (-0.76 kg [95% CI -1.10, -0.43] with placebo short acting GLP-1ra and -0.32 kg [95% CI -1.75, 1.10] with placebo long acting GLP-1ra) and by -0.31 kg (95% CI -0.64, 0.01) with placebo DPP-4i (P = 0.06 for difference with placebo short acting GLP-1ra). Placebo SGLT-2i resulted in an intermediate -0.48 kg (95% CI -0.81, -0.15) weight loss. Weight loss with placebo showed a strong correlation with the active comparator drug (r(2)  = 0.40-0.78). HbA1c changed little with placebo treatment (-0.23%, 0.10% and -0.13% for placebo GLP-1ra, DPP-4i and SGLT-2i). Adverse events occurred frequently with placebo, were often similar to the active comparator drug and led to drop-out in 2.0-2.7% of cases.

CONCLUSIONS

The response to placebo treatment was related to its active comparator, with injectable placebo GLP-1ra showing a relevant response on weight, whereas oral placebo DPP4i showed no significant response. These findings may suggest that subjective expectations influence T2DM treatment efficacy, which can possibly be employed therapeutically.

Exploring the effect of space and place on response to exercise therapy for knee and hip pain--a protocol for a double-blind randomised controlled clinical trial: the CONEX trial

INTRODUCTION

Context effects are described as effects of a given treatment, not directly caused by the treatment itself, but rather caused by the context in which treatment is delivered. Exercise is a recommended core treatment in clinical guidelines for musculoskeletal disorders. Although moderately effective overall, variation is seen in size of response to exercise across randomised controlled trial (RCT) studies. Part of this variation may be related to the fact that exercise interventions are performed in different physical environments, which may affect participants differently. The study aims to investigate the effect of exercising in a contextually enhanced physical environment for 8 weeks in people with knee or hip pain.

METHODS AND ANALYSIS

The study is a double-blind RCT. Eligible participants are 35 years or older with persisting knee and/or hip pain for 3 months. Participants are randomised to one of three groups: (1) exercise in a contextually enhanced environment, (2) exercise in a standard environment and (3) waiting list. The contextually enhanced environment is located in a newly built facility, has large windows providing abundant daylight and overlooks a recreational park. The standard environment is in a basement, has artificial lighting and is marked by years of use; that is, resembling many clinical environments. The primary outcome is the participant's global perceived effect rated on a seven-point Likert scale after 8 weeks exercise. Patient-reported and objective secondary outcomes are included.

ETHICS AND DISSEMINATION

The Regional Scientific Ethical Committee for Southern Denmark has approved the study. Study findings will be disseminated in peer-reviewed publications and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT02043613.

Dilemma of prescribing aripiprazole under the Taiwan health insurance program: a descriptive study

OBJECTIVES

Refractory major depressive disorder (MDD) is a serious problem leading to a heavy economic burden. Antipsychotic augmentation treatment with aripiprazole and quetiapine is approved for MDD patients and can achieve a high remission rate. This study aimed to examine how psychiatrists in Taiwan choose medications and how that choice is influenced by health insurance payments and administrative policy.

DESIGN

Descriptive study.

OUTCOME MEASURES

Eight questions about the choice of treatment strategy and atypical antipsychotics, and the reason to choose aripiprazole.

INTERVENTION

We designed an augmentation strategy questionnaire for psychiatrists whose patients had a poor response to antidepressants, and handed it out during the annual meeting of the Taiwanese Society of Psychiatry in October 2012. It included eight questions addressing the choice of treatment strategy and atypical antipsychotics, and the reason whether or not to choose aripiprazole as the augmentation antipsychotic.

RESULTS

Choosing antipsychotic augmentation therapy or switching to other antidepressant strategies for MDD patients with an inadequate response to antidepressants was common with a similar probability (76.1% vs 76.4%). The most frequently used antipsychotics were aripiprazole and quetiapine, however a substantial number of psychiatrists chose olanzapine, risperidone, and sulpiride. The major reason for not choosing aripiprazole was cost (52.1%), followed by insurance official policy audit and deletion in the claims review system (30.1%).

CONCLUSION

The prescribing behavior of Taiwanese psychiatrists for augmentation antipsy-chotics is affected by health insurance policy.

Paracetamol and the placebo effect in osteoarthritis trials: a missing link?

This paper addresses the role of paracetamol in placebo-controlled osteoarthritis (OA) trials and the potential contribution to the large placebo response in such trials. Paracetamol is used as rescue medication in nearly all OA placebo-controlled trials. Triggered by the discussion about the placebo effect in general and because of the lack of systematic reviews of placebo effect in OA trials, a recent meta-analysis examined the placebo effect and its potential determinants in the treatment of OA, as the main result came out that placebo is very effective in the treatment of OA, especially for pain, stiffness, and self-reported function. However, mostly limited data are available from published OA trials on the starting dose, final dose, dose over time of paracetamol use, and the percentage of patients who used rescue medication during the study. Paracetamol may be an important additional simulated effect of placebo administration mimicking the true placebo effect and thus a missing link contributing partially to the large placebo response in OA trials. Therefore, the positive effect of paracetamol on symptom relief as well as the need for standardized recording of rescue medication should be taken into account when designing, executing, and interpreting placebo-controlled OA studies.

[Laser acupuncture for chronic back pain. A double-blind clinical study]

BACKGROUND

The goal of this study was to evaluate the efficacy of laser acupuncture for the clinical picture of chronic back pain under everyday conditions using a randomized, double-blind, placebo-controlled study design. A further aim was to analyze to what extent placebo effects also influence the outcome of acupuncture under these conditions.

PATIENTS AND METHODS

The study included male and female patients with chronic back pain (lasting longer than 6 months) aged between 30 and 77 years with a pain score of at least 5 on a visual analog scale. The main criterion was achieving alleviation of pain by at least 50% 3 months after the start of treatment. The assessment tools used were the Von Korff questionnaire supplemented by the FFbH, FABQ, and SF-12. In addition, the participants were questioned about whether they perceived anything during the treatment and how certain they were that they had received treatment with active or inactive lasers.

RESULTS

A total of 111 patients were included in the study and were treated according to the randomization list in two groups each consisting of 51 subjects. The study was completed as scheduled by 102 participants. Analysis of the primary outcome measure, improvement of the pain score by more than 50% over baseline, revealed improvements in both treatment groups between the time points used for measurement. The placebo group exhibited better levels than the group that received laser treatment. No efficacy advantage of laser acupuncture over placebo treatment could be determined.

CONCLUSION

It was possible to completely blind the acupuncture forms with the study design employed. Perhaps the consistent exclusion of nonspecific treatment effects contributed to this result. It cannot be ruled out that the effects of acupuncture are based on a strong placebo effect.