On estimating treatment effects under non-compliance in randomized clinical trials: are intent-to-treat or instrumental variables analyses perfect solutions?

2007 ◽  
Vol 26 (5) ◽  
pp. 954-964 ◽  
Author(s):  
Heejung Bang ◽  
Clarence E. Davis
Keyword(s):  
Clinical Trials ◽  
Instrumental Variables ◽  
Treatment Effects ◽  
Randomized Clinical Trials ◽  
Intent To Treat

scholarly journals Estimating and reporting treatment effects in clinical trials for weight management: using estimands to interpret effects of intercurrent events and missing data

2021 ◽  
Author(s):  
Sean Wharton ◽  
Arne Astrup ◽  
Lars Endahl ◽  
Michael E. J. Lean ◽  
Altynai Satylganova ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Missing Data ◽  
Weight Management ◽  
Treatment Effect ◽  
Repeated Measures ◽  
Treatment Effects ◽  
Randomized Clinical Trials ◽  
Weight Losses ◽  
The Difference ◽  
Treatment Of Obesity

AbstractIn the approval process for new weight management therapies, regulators typically require estimates of effect size. Usually, as with other drug evaluations, the placebo-adjusted treatment effect (i.e., the difference between weight losses with pharmacotherapy and placebo, when given as an adjunct to lifestyle intervention) is provided from data in randomized clinical trials (RCTs). At first glance, this may seem appropriate and straightforward. However, weight loss is not a simple direct drug effect, but is also mediated by other factors such as changes in diet and physical activity. Interpreting observed differences between treatment arms in weight management RCTs can be challenging; intercurrent events that occur after treatment initiation may affect the interpretation of results at the end of treatment. Utilizing estimands helps to address these uncertainties and improve transparency in clinical trial reporting by better matching the treatment-effect estimates to the scientific and/or clinical questions of interest. Estimands aim to provide an indication of trial outcomes that might be expected in the same patients under different conditions. This article reviews how intercurrent events during weight management trials can influence placebo-adjusted treatment effects, depending on how they are accounted for and how missing data are handled. The most appropriate method for statistical analysis is also discussed, including assessment of the last observation carried forward approach, and more recent methods, such as multiple imputation and mixed models for repeated measures. The use of each of these approaches, and that of estimands, is discussed in the context of the SCALE phase 3a and 3b RCTs evaluating the effect of liraglutide 3.0 mg for the treatment of obesity.

Progression-free survival (PFS) as surrogate endpoint for overall survival (OS) in clinical trials of HER2-targeted agents in HER2-positive metastatic breast cancer (MBC): An individual patient data (IPD) analysis.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 610-610 ◽  
Author(s):  
Stefan Michiels ◽  
Lina Pugliano ◽  
Delphine Grun ◽  
Jana Barinoff ◽  
David A. Cameron ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Treatment Effects ◽  
Randomized Clinical Trials ◽  
Metastatic Breast ◽  
Targeted Agents ◽  
First Line ◽  
Her2 Positive ◽  
Individual Level ◽  
The Individual

610 Background: The gold standard endpoint in randomized clinical trials (RCTs) in MBC is OS, which has the disadvantage of requiring extended follow-up and being confounded by subsequent anti-cancer therapies. Although therapeutics have been approved based on PFS, its use as a primary endpoint is controversial. This study, the first IPD meta-analysis of targeted agents in MBC, aimed to collect data from RCTs of HER2-targeted agents in HER2+ MBC, assessing to what extent PFS correlates with, and may be used as, a surrogate for OS. Methods: A search was conducted in April 2011. Eligible RCTs accrued HER2+ MBC patients (pts) in 1992-2008. Collaboration was obtained from industrial partners (Roche, GSK) for industry-led studies. Investigator-assessed PFS was defined as the time from randomization to clinical or radiological progression, or death. A correlation approach was used: at the individual level, to estimate the association between PFS and OS using a bivariate survival model and at the trial level, to estimate the association between treatment effects on PFS and OS. Squared correlation values close to 1.0 would indicate strong surrogacy. Results: The search strategy resulted in 2137 eligible pts in 13 RCTs testing trastuzumab or lapatinib. We collected IPD data from 1963 pts in 9 RCTs. One phase II RCT did not have sufficient follow-up data so that 1839 pts in 8 RCTs were retained (5 evaluating trastuzumab, 3 lapatinib); 6 out of 8 RCTs were first-line. At the individual level, the Spearman rank correlation using Hougaard copula was equal to r=0.66 (95% CI 0.65 to 0.66) corresponding to an r2 of 0.42. At the trial level, the squared correlation between treatment effects on PFS and OS was provided by R2=0.33 (95% CI -0.22 to 0.86) using Hougaard copula and R2=0.53 (95% CI 0.22 to 0.83) using log hazard ratios from Cox models. Conclusions: In RCTs of HER2-targeted agents in HER2+ MBC, PFS is moderately correlated with OS and treatment effects on PFS are modestly correlated with treatment effects on OS, similarly to first-line chemotherapy in MBC (Burzykowski et al JCO 2008). PFS does not completely substitute for OS.

Mediators and Moderators of Treatment Effects in Randomized Clinical Trials

2002 ◽  
Vol 59 (10) ◽  
pp. 877 ◽  
Author(s):  
Helena Chmura Kraemer ◽  
G. Terence Wilson ◽  
Christopher G. Fairburn ◽  
W. Stewart Agras
Keyword(s):  
Clinical Trials ◽  
Treatment Effects ◽  
Randomized Clinical Trials

Comparative efficacy of triptans for the abortive treatment of migraine: A multiple treatment comparison meta-analysis

Cephalalgia ◽  
2013 ◽  
Vol 34 (4) ◽  
pp. 258-267 ◽  
Author(s):  
Kristian Thorlund ◽  
Edward J Mills ◽  
Ping Wu ◽  
Elodie Ramos ◽  
Anjan Chatterjee ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Clinical Trials ◽  
Treatment Effects ◽  
Randomized Clinical Trials ◽  
Free Response ◽  
Multiple Treatment ◽  
Treatment Comparison ◽  
Abortive Treatment ◽  
Multiple Treatment Comparison

Background Migraine is the most common neurological condition in developed countries. The abortive treatment of migraine attacks is important both for quality of life and costs associated with illness. Triptans, serotonin 5-HT1B/1D receptor agonists, effectively relieve the pain, disability, and associated symptoms of migraine while improving health-related quality of life. Although a number of direct head-to-head triptan comparisons have been made, data for all possible permutations are not available, and unlikely to ever be so, although in clinical practice such information would be useful. Objective We aimed to determine the relative efficacy of all available triptans to abort migraine headache among patients with previous adequate response to migraine treatments. Methods We included only double-blinded randomized clinical trials comparing triptans to either placebo or another triptan. Our primary outcomes were pain-free response at two hours and 24-hour sustained pain-free response, and our secondary outcomes were headache response at two hours and 24-hour sustained headache response. We used Bayesian multiple treatment comparison meta-analyses of seven triptans used in adult patients to abort migraine attacks. We applied a random-effects analysis with meta-regression adjusting for dose. Results are reported as odds ratios with 95% credible intervals. Results We included data from 74 randomized clinical trials. All triptans were significantly superior to placebo for all outcomes, with the exception of naratriptan for 24-hour sustained pain-free response. Eletriptan consistently yielded the highest treatment effect estimates. For the two-hour endpoints, eletriptan was statistically significantly superior to sumatriptan, almotriptan, naratriptan, and frovatriptan for at least one of the two outcomes. Rizatriptan yielded the second highest treatment effects followed by zolmitriptan. For the 24-hour endpoints, eletriptan was statistically significantly superior to sumatriptan, rizatriptan, almotriptan, and naratriptan for at least one of the two outcomes. Frovatriptan data were not available at that endpoint. Further, the probability that eletriptan is the most likely of all triptans to produce a favorable outcome was 68% for pain-free response at two hours, and 54% for 24-hour sustained pain-free response. Conclusion Triptans appear to offer differing treatment effects. In the populations studied eletriptan was most likely to produce pain-free responses that were sustained.

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