Utilization of model-based meta-analysis to delineate the net efficacy of taspoglutide from the response of placebo in clinical trials.
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ABSTRACT:
SUBMITTER: Li HQ
PROVIDER: S-EPMC4475818 | biostudies-literature | 2015 Jul
REPOSITORIES: biostudies-literature
Publications
Utilization of model-based meta-analysis to delineate the net efficacy of taspoglutide from the response of placebo in clinical trials.
Li Han Qing HQ Xu Jia Yin JY Jin Liang L Xin Ji Le JL
Saudi pharmaceutical journal : SPJ : the official publication of the Saudi Pharmaceutical Society 20141124 3
The objective of this study was to develop quantitative models to delineate the net efficacy of taspoglutide on fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) from the response of placebo in type 2 diabetes patients, and further find pharmacodynamic potency of taspoglutide and FPG for half of maximum reduction responses of FPG and HbA1c, respectively. Several PD data about taspoglutide treatments for type 2 diabetes patients were digitalized from the published papers related wi ...[more]
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Project description:ImportanceBecause increasing placebo response rates decrease drug-placebo differences and increase the number of failed trials, it is imperative to determine what is causing this trend.ObjectivesTo investigate the relationship between antipsychotic medication and placebo response by publication year, and to identify associated study design and implementation variables.Data sourcesMEDLINE, PsycINFO, and PubMed were searched to identify randomized clinical trials of antipsychotic medications published from 1960 to July 2013.Study selectionIncluded were randomized clinical trials lasting 4 to 24 weeks, contrasting antipsychotic medication with placebo or an active comparator, and enrolling patients 18 years of age or older with schizophrenia or schizoaffective disorder.Data extraction and synthesisStandardized mean change scores were calculated for each treatment arm, plotted against publication year, and tested with Spearman rank correlation coefficients. Hierarchical linear modeling identified factors associated with the standardized mean change across medication and placebo treatment arms.Main outcomes and measuresWe hypothesized that the mean change in placebo-treated patients would significantly increase from 1960 to the present, that a greater change would be observed in active comparator vs placebo-controlled trials, and that more protocol visits would increase the symptom change observed.ResultsIn the 105 trials examined, the mean change observed in placebo arms increased significantly with year of publication (n=39, r=0.52, P=.001), while the mean change in effective dose medication arms decreased significantly (n=208, r=-0.26, P<.001). Significant interactions were found between assignment to effective dose medication and publication year (t260=-5.55, P<.001), baseline severity (t260=5.08, P<.001), and study duration (t260=-3.76, P<.001), indicating that the average drug-placebo difference significantly decreased over time, with decreasing baseline severity and with increasing study duration. Medication treatment in comparator studies was associated with significantly more improvement than medication treatment in placebo-controlled trials (t93=2.73, P=.008).Conclusions and relevanceThe average treatment change associated with placebo treatment in antipsychotic trials increased since 1960, while the change associated with medication treatment decreased. Changes in randomized clinical trials leading to inflation of baseline scores, enrollment of less severely ill participants, and higher expectations of patients may all be responsible.
| S-EPMC4256120 | biostudies-literature
Project description:ImportanceIn osteoarthritis (OA) clinical trials, a placebo is often used as control. Therefore, a thorough understanding of the placebo response is important for guiding drug development in OA.ObjectiveTo develop an oral placebo response model for OA.Data sourcesPubMed, EMBASE, and Cochrane Library databases were searched systematically from January 1, 1991, to July 2, 2022.Study selectionRandomized double-blind placebo-controlled trials of patients with primary OA were included. The interventions and placebo were administered orally. A total of 3032 trials were identified; of these, 130 (4.3%) met the inclusion criteria.Data extraction and synthesisWestern Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, dosage form of the placebo, sample size, proportion of patients who previously used nonsteroidal anti-inflammatory drugs, publication year, intervention categories, Kellgren-Lawrence grades, proportion of White patients, duration of pain, funding source, and risk of bias were extracted. A model-based meta-analysis was used to evaluate the time course of the placebo response in OA treatment and estimate the influencing factors. For subgroup analyses, a meta-analysis with a random-effects model was used to summarize the typical values of the model parameters and their SEs.Main outcomes and measuresThe primary end point was the time course of the oral placebo response on the WOMAC pain, stiffness, and function subscale scores.ResultsThe 130 trials selected for analysis included 12 673 participants (mean age, 59.9 years; 68.9% women). The baseline scores of WOMAC pain, stiffness, and function subscales were found to be significantly associated with the placebo response. The placebo response reached 90% of its maximum response between 5 and 7 weeks. The placebo responses on the WOMAC subscales were also associated with the sample size, proportion of patients who had previously used nonsteroidal anti-inflammatory drugs, intervention drugs, and publication year.Conclusions and relevanceIn this study, an oral placebo response model of OA was developed that may quantitatively describe the placebo response at different baseline levels of symptoms. The findings may provide valuable references for future clinical trial design and decision-making.
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Project description:Previous systematic reviews and meta-analyses of randomized controlled trials have reported controversial findings regarding the effects of melatonin on pain reduction. The aim of this study was to evaluate the efficacy of melatonin on pain among adults using a meta-analysis of randomized, double-blind, placebo-controlled trials (RDBPCTs). PubMed, EMBASE, the Cochrane Library, and the bibliographies of relevant articles were searched up to February 2020. Two of the authors independently evaluated eligibility of the studies based on the pre-determined criteria and extracted data. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) for the pain score change were calculated using a random-effects meta-analysis. Out of 463 that met the initial criteria, a total of 30 trials, which involved 1967 participants with 983 in an intervention group and 984 in a control group, were included in the final analysis. In a random-effects meta-analysis, the use of melatonin reduced chronic pain in all the trials (5 studies, SMD -0.65, 95% CI -0.96 to -0.34, I2= 57.2%) and high-quality trials (4 studies, SMD -0.62, 95% CI -1.01 to -0.23, I2= 49.3%). Moreover, the use of melatonin significantly reduced acute postoperative pain (11 studies, SMD -0.82, 95% CI -1.40 to -0.25, I2= 93.0%). However, the subgroup meta-analysis of high-quality RDBPCTs showed no significant association between them (6 studies, SMD -0.21, 95 % CI -0.66 to 0.24, I2= 82.4%). The current study suggests that melatonin might be used in treatment of chronic pain, while there is no sufficient evidence for acute postoperative or procedural pain. Further trials are warranted to confirm its analgesic effect.
| S-EPMC7291209 | biostudies-literature
Project description:AimObesity is a global epidemic. The FDA has approved glucagon-like peptide-1 (GLP-1) receptor agonists such as Liraglutide, Semaglutide, and the GLP-1/gastric inhibitory polypeptide (GIP) dual agonist Tirzepatide for the treatment of obesity. Clinical trials of GLP-1/GIP/glucagon(GCG) triple agonists are ongoing. This study compared the efficacy and safety profiles of different GLP-1 receptor agonists (GLP-1RAs) for weight reduction and explored the related influencing factors, providing quantitative information for the development of GLP-1RAs and their clinical use.MethodsThis systematic review of public databases included placebo-controlled randomized clinical trials of GLP-1RAs. Time-course, dose-response, and covariate models were used to describe the efficacy characteristics and influencing factors of different GLP-1RAs. Subgroup analyses were performed to explore efficacy differences in receptor specificity. Meta-analyses compared the incidence of adverse event and dropout rates among different GLP-1RAs.ResultsFifty-five studies involving 16,269 participants and 12 GLP-1RAs were included. Six drugs showed significant dose-response relationships. The maximum weight reduction effect ranged from 4.25 kg (Liraglutide) to 22.6 kg (Retatrutide). Reported onset times ranged from 6.4 weeks (Orforglipron) to 19.5 weeks (Tirzepatide). At 52 weeks, weight reduction effects were 7.03 kg, 11.07 kg, and 24.15 kg for mono-agonists, dual-agonists, and tri-agonists, respectively. There was a significant negative correlation in the exponential pattern between age and weight reduction effect, whereas baseline weight and BMI had no significant impact. Common adverse events of GLP-1RAs, reported in the literature include nausea, vomiting, diarrhea, and constipation, with a significantly higher incidence of nausea than that of placebo.ConclusionsThis study provides a quantitative evaluation of the efficacy and safety of GLP-1RAs and offers valuable insights into the assessment of new drugs for weight reduction.
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Project description:Objective. To explore the efficacy of Chinese herbal medicine in treating diarrhea-predominant irritable bowel syndrome (D-IBS). Methods. Four English and four Chinese databases were searched through November, 2015. Randomized, double-blind and placebo-controlled trials were selected. Data extraction and quality evaluation were performed by two authors independently. RevMan 5.2.0 software was applied to analyze the data of included trials. Results. A total of 14 trials involving 1551 patients were included. Meta-analysis demonstrated superior global symptom improvement (RR = 1.62; 95% CI 1.31, 2.00; P < 0.00001; number needed to treat = 3.6), abdominal pain improvement (RR = 1.95; 95% CI 1.61, 2.35; P < 0.00001), diarrhea improvement (RR = 1.87; 95% CI 1.60, 2.20; P < 0.00001), pain threshold assessment (MD = 54.53; 95% CI 38.76, 70.30; P < 0.00001), and lower IBS Symptom Severity Score (SMD = -1.01; 95% CI -1.72, -0.30; P = 0.005), when compared with placebo, while for defecation threshold assessment, quality of life, and adverse events, no differences were found between treatment groups and controlled groups. Conclusion. This meta-analysis shows that Chinese herbal medicine is an effective and safe treatment for D-IBS. However, due to the small sample size and high heterogeneity, further studies are required.
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Project description:BackgroundThe issue of unblinded outcome-assessors and patients has repeatedly been stressed as a flaw in allegedly double-blind antidepressant trials. Unblinding bias can for example result from a drug's marked side effects. If such unblinding bias is present for a given drug, then it might be expected that the placebos of that drug are rated significantly less effective than that of other antidepressants.MethodsTo test this hypothesis, the present exploratory analysis conducted a Bayesian network meta-analysis (NMA) comparing the efficacy of 19 different placebos in placebo-controlled trials provided in the dataset by Cipriani et al. (Lancet 2018; 391: 1357-66). Primary outcome was efficacy (continuous) estimated on the standardized mean difference (SMD) scale and defined as the pre-post change on the Hamilton Depression scale (HAMD-17), on which information was available in N = 258 trials.ResultsComparative placebo ranking suggested mirtazapine-placebo (SMD -2.0 [- 5.0-1.0 95% CrI]) to be the most, and amitriptyline- (SMD 1.2 [- 1.6-3.9 95% CrI]) and trazodone- (SMD 2.1 [- 0.9-5.2 95% CrI]) placebos to be the least effective placebos. Other placebos suggested to be more effective than amitriptyline- and trazodone-placebos (based on 95% CrIs excluding zero) were citalopram, desvenlafaxine, duloxetine, escitalopram, fluoxetine, sertraline, and venlafaxine placebos. These NMA results were corroborated by the observation that the relative efficacy between drug and placebo was considerably larger for amitriptyline and trazodone than for instance mirtazapine, duloxetine, and venlafaxine, supported by a small and insignificant correlation between drug-efficacy and placebo-efficacy (r = - 0.202, p = 0.408).DiscussionThe present exploratory NMA indicates that distinguishable side effects of older drugs may unblind outcome-assessors thus resulting in overestimation of the average drug-placebo difference and underrating bias in placebo-arms, particularly for the older antidepressant drugs amitriptyline and trazodone. If confirmed in prospective studies, these findings suggest that efficacy rankings for antidepressants are susceptible to bias and should be considered unreliable or misleading. The analysis is limited by the focus on the single-comparison placebos (76%, i.e., placebos assessed in two-arm trials), since double-comparison placebos (25%, i.e., placebos assessed in three-arm trials) are hard to interpret and therefore not included in the present interpretation. Another limitation is the problem of multiplicity, which was only approximately accounted for in the Bayesian NMA by modelling treatment effects as exchangeable.
| S-EPMC7487933 | biostudies-literature
Project description:BackgroundRecent meta-analyses reported placebo response rate in antidepressant trials to be stable since the 1970s. These meta-analyses however were limited in considering only linear time trends, assessed trial-level covariates based on single-model hypothesis testing only, and did not adjust for small-study effects (SSE), a well-known but not yet formally assessed bias in antidepressant trials.MethodsThis secondary meta-analysis extends previous work by modeling nonlinear time trends, assessing the relative importance of trial-level covariates using a multimodel approach, and rigorously adjusting for SSE. Outcomes were placebo efficacy (continuous), based on the Hamilton Depression Scale, and placebo response rate.ResultsResults suggested that any nonlinear time trends in both placebo efficacy (continuous) and response rate were best explained by SSE. Adjusting for SSE revealed a significant gradual increase in placebo efficacy (continuous) from 1979 to 2014. A similar observation was made for placebo response rate, but did not reach significance due higher susceptibility to SSE. By contrast, trial-level covariates alone were found to be insufficient in explaining time trends.ConclusionThe present findings contribute to the ongoing debate on antidepressant placebo outcomes and highlight the need to adjust for bias introduced by SSE. The results are of clinical relevance because SSE may affect the evaluation of success or failure in antidepressant trials.
| S-EPMC7399231 | biostudies-literature
Project description:Differences in efficacy between antipsychotics and placebo in schizophrenia trials have decreased over the past decades. Previous studies have tried to identify potential explanatory factors focusing on response to placebo; however, it is still not clear which factors, if any, specifically moderate drug-response, as they may be different from those moderating placebo-response. Therefore, in this meta-regression analysis we explore whether there is an interaction between drug-response and placebo-response in terms of effect size. We systematically searched multiple electronic databases, ClinicalTrials.gov, and the US Food and Drug Administration website for randomized, placebo-controlled trials investigating the efficacy of antipsychotics in patients with acute schizophrenia (last update: October 2016). The main outcome was the change on the Brief Psychiatric Rating Scale or the Positive and Negative Syndrome Scale score from baseline to endpoint after at least 3 weeks of treatment. Multiple patient-, design-, and drug-related potential predictors of response were analyzed by meta-regressions, as predefined in the study protocol. Overall, 167 trials with 28,102 participants were included. Publication year, the number of participants and sites, mean dose, minimum severity threshold as an inclusion criterion, chronicity, industry sponsorship, type of rating scale, diagnostic criteria, and number of medications had a different impact on drug and placebo response. By contrast, baseline severity, duration of wash-out, study duration, and study region affected drug and placebo response in a similar way without a net effect on effect sizes. No other factors had a significant effect on either drug-response or placebo-response. In conclusion, as individual moderators may have different impact on placebo-response and drug-response, it is important to consider also the specific factors influencing drug-response in order to fully understand the difference between antipsychotics and placebo. These results shed further light on the phenomenon of decreasing effect size of antipsychotics for schizophrenia over time and should help design future randomized controlled trials in the field (Prospero registration number CRD42013003342).
| S-EPMC6785090 | biostudies-literature
Project description:BackgroundContextual effects (i.e., placebo response) refer to all health changes resulting from administering an apparently inactive treatment. In a randomized clinical trial (RCT), the overall treatment effect (i.e., the post-treatment effect in the intervention group) can be regarded as the true effect of the intervention plus the impact of contextual effects. This meta-research was conducted to examine the average proportion of the overall treatment effect attributable to contextual effects in RCTs across clinical conditions and treatments and explore whether it varies with trial contextual factors.MethodsData was extracted from trials included in the main meta-analysis from the latest update of the Cochrane review on "Placebo interventions for all clinical conditions" (searched from 1966 to March 2008). Only RCTs reported in English having an experimental intervention group, a placebo comparator group, and a no-treatment control group were eligible.ResultsIn total, 186 trials (16,655 patients) were included. On average, 54% (0.54, 95%CI 0.46 to 0.64) of the overall treatment effect was attributable to contextual effects. The contextual effects were higher for trials with blinded outcome assessor and concealed allocation. The contextual effects appeared to increase proportional to the placebo effect, lower mean age, and proportion of females.ConclusionApproximately half of the overall treatment effect in RCTs seems attributable to contextual effects rather than to the specific effect of treatments. As the study did not include all important contextual factors (e.g., patient-provider interaction), the true proportion of contextual effects could differ from the study's results. However, contextual effects should be considered when assessing treatment effects in clinical practice.Trial registrationPROSPERO CRD42019130257 . Registered on April 19, 2019.
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Project description:ImportanceAntidepressants are commonly used worldwide to treat major depressive disorder. Symptomatic response to antidepressants can vary depending on differences between individuals; however, this variability may reflect nonspecific or random factors.ObjectivesTo investigate the assumption of systematic variability in symptomatic response to antidepressants and to assess whether this variability is associated with severity of major depressive disorder, antidepressant class, or year of study publication.Data sourcesData used were from a recent network meta-analysis of acute treatment with licensed antidepressants in adults with major depressive disorder. The following databases were searched from inception to January 8, 2016: the Cochrane Central Register of Controlled Trials, CINAHL, Embase, LILACS database, MEDLINE, MEDLINE In-Process, and PsycINFO. Additional sources were international trial registries, drug approval agency websites, and key scientific journals.Study selectionAnalysis was restricted to double-blind, randomized placebo-controlled trials with available data at the study's end point.Data extraction and synthesisBaseline and end point means, SDs, number of participants in each group, antidepressant class, and publication year were extracted. The data were analyzed between August 14 and November 18, 2019.Main outcomes and measuresWith the use of validated methods, coefficients of variation were derived for antidepressants and placebo, and their ratios were calculated to compare outcome variability between antidepressant and placebo. Ratios were entered into a random-effects model, with the expectation that response to antidepressants would be more variable than response to placebo. Analysis was repeated after stratifying by baseline severity of depression, antidepressant class (selective serotonin reuptake inhibitors: citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, and vilazodone; serotonin and norepinephrine reuptake inhibitors: desvenlafaxine and venlafaxine; norepinephrine-dopamine reuptake inhibitor: bupropion; noradrenergic agents: amitriptyline and reboxetine; and other antidepressants: agomelatine, mirtazapine, and trazodone), and publication year.ResultsIn the 87 eligible randomized placebo-controlled trials (17 540 unique participants), there was significantly more variability in response to antidepressants than to placebo (coefficients of variation ratio, 1.14; 95% CI, 1.11-1.17; P < .001). Baseline severity of depression did not moderate variability in response to antidepressants. Variability in response to selective serotonin reuptake inhibitors was lower than variability in response to noradrenergic agents (coefficients of variation ratio, 0.88; 95% CI, 0.80-0.97; P = .01), as was the variability in response to other antidepressants compared with noradrenergic agents (coefficients of variation ratio, 0.87; 95% CI, 0.79-0.97; P = .001). Variability also tended to be lower in studies that were published more recently, with coefficients of variation changing by a value of 0.005 (95% CI, 0.002-0.008; P = .003) for every year a study is more recent.Conclusions and relevanceIndividual differences may be systematically associated with responses to antidepressants in major depressive disorder beyond placebo effects or statistical factors. This study provides empirical support for identifying moderators and personalizing antidepressant treatment.
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