Factors That Predict Magnitude, Timing, and Persistence of Placebo-Like Response in Patients With Irritable Bowel Syndrome

BACKGROUND AND AIMS

Placebo response impedes the development of novel irritable bowel syndrome (IBS) therapies and the interpretability of randomized clinical trials. This study sought to characterize the magnitude, timing, and durability of IBS symptom relief in patients undergoing a non-drug placebo-like control.

METHODS

One hundred forty-five Rome III-diagnosed patients (80% F, M age = 42 years) were assigned to education/nondirective support delivered over a 10-week acute phase. Treatment response was based on the IBS version of the Clinical Global Improvement Scale completed 2 weeks after treatment ended. Candidate predictors were assessed at baseline (eg, emotion regulation, pain catastrophizing, distress, neuroticism, stress, somatization, gastrointestinal-specific anxiety) or clinically relevant points during treatment (patient-provider relationship, treatment expectancy/credibility).

RESULTS

Midtreatment response was associated with lower levels of stress and somatization at baseline and greater patient-provider agreement on treatment tasks (P < .001). Treatment response was associated with baseline gastroenterologist-rated IBS severity, anxiety, ability to reappraise emotions to reduce their impact [cognitive reappraisal], and agreement that provider and patient shared goals from provider perspective (P < .001). The day-to-day ability to reappraise emotions at baseline distinguished rapid from delayed placebo responders (P = .011).

CONCLUSION

Patient beliefs (eg, perceived stress, cognitive reappraisal) impacted the magnitude, timing, and persistence of placebo response measured at midway point of acute phase and 2 weeks after treatment discontinuation. Baseline beliefs that patients could alter the impact of stressful events by rethinking their unpleasantness distinguished rapid vs delayed placebo responders. Collaborative agreement between doctor and patient around shared tasks/goals from the clinician perspective predicted placebo response.

[Nocebo placebo, the hidden side of our treatments]

NOCEBO PLACEBO, THE HIDDEN SIDE OF OUR TREATMENTS. Our knowledge of the placebo effect and its opposite, the nocebo effect, has changed dramatically in the last 20 years. Any treatment activity induces this type of effect. The placebo groups in clinical studies have biases that profoundly alter their neutrality. The nocebo effect is omnipresent in daily practice, it contributes to induce many of the adverse drug effects. The use of «impure» placebos is also widespread in daily practice. The placebo effect has an objectivable and reproducible neurobiological substrate. Its therapeutic effects are well documented. Disorders, symptoms involving the central nervous system (CNS) respond more easily to placebo. These new data make it possible to improve clinical practices by developing the quality of relationships with patients and families as well as the methodology of clinical trials.

The power of the placebo effect in diabetes: A systematic review and meta-analysis

This review aims to identify the magnitude of the placebo effect in people with type 2 diabetes mellitus. Literature research was conducted Medline, Embase and Virtual Health Library for studies published between the date of inception and June 2021. The eligibility criteria included randomized controlled trials, showing comparison to placebo, having participants with type 2 diabetes mellitus, and having glycated hemoglobin (HbA1c) as the primary outcome. Meta-analysis was conducted with the effect of changing HbA1c in relation to the baseline. Exploration of heterogeneity was performed.The meta-analysis showed an increase in the average of HbA1c compared to the baseline of 0.14% (95% CI: 0.07-0.21). There was a significant difference between follow-up times (p = 0.03) and between administration routes (p = 0.01), with an increase in HbA1c in the oral route [0.15% (95% CI: 0.07-0.23)]. The meta-regression of the year of publication showed a significant downward trend (p = 0.01) of the increase in HbA1c compared to the baseline.In this study, the expected placebo effect of Hba1c reduction was not found; instead, higher Hba1c levels were observed in the control groups, although this effect was reduced over the years. Registration: PROSPERO ID CRD42020172797.

Feasibility of Using Detuned Laser as a Placebo In Manual Therapy Research: An Analysis of Participant Perceptions

OBJECTIVE

The purpose of this study was to determine the feasibility of using detuned laser as a placebo intervention in manual therapy research.

METHODS

We performed a secondary data analysis of a randomized controlled trial. In our analysis, 30 participants with chronic ankle instability (manual therapy group: n = 13, age = 33.1 ± 8.1 years, female participants = 50%; detuned laser group: n = 17, age = 31.9 ± 11.8 years, female participants = 72%) were asked to indicate which intervention (manual therapy [active] or detuned laser [placebo]), they thought they had received and to give a confidence rating on their response regarding the received intervention at the conclusion of the course of intervention. Independent t tests were used to compare the groups. Participants in both groups were asked the following open-ended question: "What did you think of the intervention?".

RESULTS

There were 52.9% participants in the detuned laser group and 53.8% participants in the manual therapy group who perceived that they had received the active intervention. The confidence ratings about their perceptions (6.7 ± 2.0, detuned laser group; 6.3 ± 2.4, manual therapy group) (P = .66) and the self-reported recovery ratings (1.9 ± 1.5 and 1.8 ± 1.2, respectively) (P = .77) were similar.

CONCLUSIONS

Participants in this study confidently perceived that detuned laser was an active intervention. They positively rated their recovery following the course of the placebo intervention and perceived that detuned laser was effective in treating their condition. Therefore, it is feasible for detuned laser to be used as a placebo for manual therapy trials.

Low-Dose Testosterone Augmentation for Antidepressant-Resistant Major Depressive Disorder in Women: An 8-Week Randomized Placebo-Controlled Study

OBJECTIVE

Low-dose testosterone has been shown to improve depression symptom severity, fatigue, and sexual function in small studies in women not formally diagnosed with major depressive disorder. The authors sought to determine whether adjunctive low-dose transdermal testosterone improves depression symptom severity, fatigue, and sexual function in women with antidepressant-resistant major depression. A functional MRI (fMRI) substudy examined effects on activity in the anterior cingulate cortex (ACC), a brain region important in mood regulation.

METHODS

The authors conducted an 8-week randomized double-blind placebo-controlled trial of adjunctive testosterone cream in 101 women, ages 21-70, with antidepressant-resistant major depression. The primary outcome measure was depression symptom severity as assessed by the Montgomery-Åsberg Depression Rating Scale (MADRS). Secondary endpoints included fatigue, sexual function, and safety measures. The primary outcome of the fMRI substudy (N=20) was change in ACC activity.

RESULTS

The participants' mean age was 47 years (SD=14) and their mean baseline MADRS score was 26.6 (SD=5.9). Eighty-seven (86%) participants completed 8 weeks of treatment. MADRS scores decreased in both study arms from baseline to week 8 (testosterone arm: from 26.8 [SD=6.3] to 15.3 [SD=9.6]; placebo arm: from 26.3 [SD=5.4] to 14.4 [SD=9.3]), with no significant difference between groups. Improvement in fatigue and sexual function did not differ between groups, nor did side effects. fMRI results showed a relationship between ACC activation and androgen levels before treatment but no difference in ACC activation with testosterone compared with placebo.

CONCLUSIONS

Adjunctive transdermal testosterone, although well tolerated, was not more effective than placebo in improving symptoms of depression, fatigue, or sexual dysfunction. Imaging in a subset of participants demonstrated that testosterone did not result in greater activation of the ACC.

Response to Placebo, Measured by Endoscopic Evaluation of Crohn's Disease Activity, in a Pooled Analysis of Data From 5 Randomized Controlled Induction Trials

BACKGROUND & AIMS

Endoscopy is used to measure activity of Crohn's disease (CD) and determine eligibility and outcomes of participants in randomized controlled trials of therapeutic agents. We aimed to estimate the rate of response to placebo in trials, based on endoscopic evaluation of CD activity, and identify factors that affect this response.

METHODS

We collected patient-level data from randomized, double-blind, placebo-controlled trials of therapeutic agents for CD that included centrally-read endoscopic assessments with validated scoring indices. We analyzed data from induction trials of eldelumab, filgotinib, risankizumab, and ustekinumab (from 188 patients given placebo). The primary outcome was the rate of response to placebo, based on endoscopic assessment of CD activity (>50% reduction in the simple endoscopic score for CD). Rate of remission, based on endoscopic score, was a secondary outcome. Overall rates of response to placebo were calculated using the inverse variance-weighted average method and presented with 95% CIs. We performed a multi-variable meta-regression analysis to identify determinants of response to placebo, assessed endoscopically, using patient-level data from the filgotinib and ustekinumab trials.

RESULTS

The pooled rate of response among patients given placebo was 16.2% (95% CI, 10.5%-22.0%) and the rate of remission in this group was 5.2% (95% CI, 1.7%-8.8%). Prior exposure to tumor necrosis factor antagonists (odds ratio, 0.31; 95% CI, 0.10-0.93; P = .036) and increased concentration of C-reactive protein at baseline (odds ratio, 0.93; 95% CI, 0.87-0.98; P = .014 per 10 mg/L increase) were independently associated with lower rates of response to placebo.

CONCLUSIONS

Rates of response and remission to placebo, determined by centrally-read endoscopy, in induction trials of therapies for CD are low. These estimates are important for sample size calculations for randomized placebo-controlled trials that use the Simple Endoscopic Score for CD as an endpoint. They also provide a benchmark to interpret findings from non-placebo controlled, prospective, randomized, unblinded trials.

Comparison of Vitex agnus-castus Extracts with Placebo in Reducing Menopausal Symptoms: A Randomized Double-Blind Study

BACKGROUND

Menopausal symptoms have remarkable negative effects on women's quality of life, justifying the need to assess various therapeutic options. This research aimed to determine the effectiveness of Vitex agnus-castus extracts in alleviating menopausal symptoms in comparison with that of placebo.

METHODS

This study was a randomized controlled double-blind clinical trial with a study group of 52 women referred to a clinic in Kermanshah in 2017. The participants were randomly divided into two groups: Vitex group (26 subjects) and placebo group (26 subjects). Menopausal symptoms were assessed using the Greene Scale before and 8 weeks after the intervention.

RESULTS

After the intervention, the mean scores for total menopausal disorder, anxiety, and vasomotor dysfunction were significantly lower in the Vitex group than in the placebo group (P<0.05). The mean scores of the variables of somatic complications, depression, and sexual dysfunction did not show significant differences between the Vitex and placebo groups (P>0.05).

CONCLUSION

Administration of Vitex agnus-castus extracts as a phytoestrogenic medicine can alleviate menopausal symptoms in women.

Effects of acute sleep deprivation and caffeine supplementation on anaerobic performance

Purpose

Athletes involved in team sports may be subject to varying degrees of sleep deprivation either before or after training and competition. Despite the belief among athletes and coaches of the importance of adequate sleep for ensuing performance, the effect of sleep loss on team-sport anaerobic performance remains unclear. There is conflicting evidence in the scientific literature as to the impact of acute sleep deprivation and caffeine supplementation on anaerobic performance indices. The purpose of this study is to investigate the effect of 24 hours of acute sleep deprivation on anaerobic performance and the effect of caffeine supplementation on anaerobic performance in the sleep deprived state.

Methods

11 club level games players (n=11, 25±4 yr, 178±7.5 cm, 80.2±10.4 kg, 15.1±5.6% body fat) participated in a repeated measures double-blinded placebo control trial. Following familiarisation, each participant returned for testing on three separate occasions. One of the testing sessions took place following a night of normal sleep and the other two sessions took place following 24 hours of sleep deprivation with supplementation of either placebo or 6 mg.kg- 1 of caffeine. During each testing session participants performed the vertical jump height, 20-m straight sprint, Illinois speed agility test and 5-m shuttle run.

Results

No significant differences were detected comparing non sleep deprived and sleep deprived interventions in any of the assessed outcome measures. There were also no significant differences observed in any of the outcome measures when comparing caffeine and placebo data in the sleep deprived state.

Conclusion

In this cohort of athletes, a 24-h period of acute sleep deprivation did not have any significant impact on anaerobic performance. Caffeine also did not have any effect of on anaerobic performance in the sleep-deprived state.

Predictors of Erectile Function Normalization in Men With Erectile Dysfunction Treated With Placebo

BACKGROUND

Clinical study and practice data have shown sildenafil improves sexual function in men with erectile dysfunction (ED). However, some men treated with placebo in double-blind, placebo-controlled sildenafil studies also report improved erectile function as measured by International Index of Erectile Function (IIEF)-Erectile Function Domain (EFD) scores.

AIM

This analysis estimated the relationship between post-baseline IIEF-EFD scores and demographic variables, including co-morbidities, in men with ED receiving placebo in flexible-dose sildenafil studies.

METHODS

Placebo-treated participants in the intent-to-treat population of 42 double-blind, placebo-controlled, flexible-dose, sildenafil studies were included. A participant was classified as a placebo responder if the IIEF-EFD score was ≥26 at the last visit.

OUTCOMES

Variables assessed were age (<45, 45-64, ≥65 years), race, body mass index, co-morbidities (cardiovascular disease/hypertension, diabetes mellitus, depression), date the last study dose was taken, study completion date, ED etiology (psychogenic, organic, mixed), history of cigarette smoking, ED duration, baseline IIEF-EFD score (≤10, 11-16, ≥17), and treatment duration. Stepwise multivariate logistic regression models assessed the odds of being a responder vs a non-responder for each variable.

RESULTS

A total of 4,360 men were included; 13.5% were responders. Odds estimates indicated the largest likelihood of placebo response occurred in men who were black (odds = 20.2, P < .0001), were younger than 45 years (odds = 7.3, P < .0001), had mild ED (baseline IIEF-EFD ≥17; odds >100, P < .0001), and did not have diabetes (odds = 4.5, P < .0001). The likelihood of a placebo response decreased as ED duration increased (odds = 0.74, P < .0001). The frequency of common adverse events was similar between placebo responders and non-responders.

CLINICAL TRANSLATION

These findings contribute to the improved understanding of predictors of placebo response in sildenafil clinical studies. Elucidation of these factors may contribute to the development of further interventions and treatment strategies and best practices for clinical trials.

STRENGTHS AND CONCLUSIONS

Strengths of this analysis include the large and diverse population and the duration of follow-up. Limitations include those associated with retrospective analyses and the inability to ascertain to what extent other demographic factors might have contributed to the placebo responses or how these placebo responses might be related to the natural course of ED.

CONCLUSIONS

Certain demographics, co-morbidities, and condition characteristics predicted the odds of a placebo response in sildenafil clinical studies of ED. Underlying reasons behind a placebo response warrant further evaluation. Mulhall JP, Carlsson M, Stecher V, et al. Predictors of Erectile Function Normalization in Men With Erectile Dysfunction Treated With Placebo. J Sex Med 2018;15:866-872.

Validation of a New Placebo Interferential Current Method: A New Placebo Method of Electrostimulation

Objective

The present study aimed to investigate if a new placebo device for interferential current (IFC) that delivers current during only the first 40 seconds of stimulation is effective at promoting adequate subject blinding.

Methods

Seventy-five subjects were recruited and enrolled into three groups: active IFC, inactive placebo, and new placebo. Pressure pain threshold (PPT), cutaneous sensory threshold (CST), and pain intensity were measured before and after the intervention. After the final assessment, the subjects and the investigator who applied the current were asked about the type of stimulation administered.

Results

None of the placebo forms studied resulted in significant changes to PPT, CST, or pain intensity. The subjects stimulated with active IFC at high intensities (> 17 mA) of stimulation showed higher PPT and CST and lower pain intensity than subjects stimulated at low intensities ( p < 0.03). The new placebo method blinded the investigator in 100% of cases of IFC and 60% of subjects stimulated, whereas for inactive placebo, the investigator was blinded at a rate of 0% and 34% of subjects.

Conclusion

The new method of placebo IFC was effective for blinding of research investigators and most of the active IFC-treated subjects, promoting an appropriate placebo method.

Placebo response rate in clinical trials of fistulizing Crohn's disease: systematic review and meta-analysis

BACKGROUND & AIMS

It is important to determine the magnitude and identify modifiers of the rate of response to placebo in clinical trials of fistulizing Crohn's disease (CD), to understand disease progression, and to calculate sample size. We conducted a systematic review and meta-analysis of rates of response to placebo in trials of patients with fistulizing CD.

METHODS

We searched MEDLINE, EMBASE, EMBASE CLASSIC, and the Cochrane central register of controlled trials for randomized controlled trials (RCTs) comparing pharmacologic agents with placebo in adults with fistulizing CD. We identified studies that reported complete fistula closure, partial closure, or response. Data were extracted as intention-to-treat analyses and pooled by using a random-effects model. Proportions of patients who received placebo and had complete or partial fistula(e) closure were calculated, with 95% confidence intervals (CIs). The effects of trial characteristics on the magnitude of response to placebo were examined.

RESULTS

Thirteen RCTs were eligible for our analysis; these included 579 patients assigned to placebo groups. The pooled rate of response to placebo, among all RCTs, for complete fistula closure was 15.6% (95% CI, 10.9%-20.9%), with significant heterogeneity (I(2) = 62.5%, P = .001). The pooled rate of response to placebo for partial fistula closure or response in 9 trials, comprising 423 patients, was 18.3% (95% CI, 14.8%-22.1%). Rates of response to placebo were significantly lower in trials with shorter durations of therapy and shorter intervals to assessment of fistula closure. Neither exposure to the pharmacologic agent during the induction phase of the same (or related) RCT nor concomitant medications had any effect.

CONCLUSIONS

In a meta-analysis of rate of response to placebo in patients with fistulizing CD, we found that fistulae closed in almost 1/6 patients given placebo in RCTs of pharmacologic agents. Future research should identify characteristics of patients that predict response to placebo.

The placebo effect in clinical trials for alcohol dependence: an exploratory analysis of 51 naltrexone and acamprosate studies

BACKGROUND

The placebo effect often undermines efforts to determine treatment effectiveness in clinical trials. A significant placebo response occurs in alcohol trials, but it is not well understood. The purpose of this study was to characterize the placebo response across multiple naltrexone and acamprosate studies.

METHODS

Fifty-one trials, 3 with a naltrexone and an acamprosate arm, 31 with at least 1 naltrexone arm, and 17 with at least 1 acamprosate arm, were identified from Cochrane reviews and PubMed search. To be included in this study, patients had to be at least 18 years old, abstinent from alcohol before randomization, and meet a diagnosis of alcohol dependence. Pearson correlation coefficients (rp ) and simple linear regression were used to describe the strength of linear relationships between placebo response and treatment effect size. Spearman's rank correlation coefficients (rs ) were used to examine the strength of associations between study characteristics and placebo response.

RESULTS

For the end point measures of percent days abstinent and total abstinence, a negative relationship was evident between placebo response and treatment effect size in the naltrexone trials (rp  = -0.55, p < 0.01 and rp  = -0.20, p = 0.35, respectively) as well as in the acamprosate trials (rp  = -0.45, p = 0.09 and rp  = -0.56, p = 0.01, respectively). The placebo response for percent days abstinent was negatively correlated with mean age of participants (rs  = -0.42, p = 0.05) across naltrexone trials and positively correlated with publication year (rs  = 0.57, p = 0.03) across acamprosate trials. However, these 2 study characteristics were not significantly correlated with treatment effect size.

CONCLUSIONS

The placebo response varied considerably across trials and was negatively correlated with the treatment effect size. Additional studies are required to fully understand the complex nature of the placebo response and to evaluate approaches to minimize its effects.