Why caution is recommended with post-hoc individual patient matching for estimation of treatment effect in parallel-group randomized controlled trials: The case of acute stroke trials

2013 ◽  
Vol 32 (25) ◽  
pp. 4467-4481 ◽  
Author(s):  
Nahid Jafari ◽  
John Hearne ◽  
Leonid Churilov
Keyword(s):  
Randomized Controlled Trials ◽  
Acute Stroke ◽  
Treatment Effect ◽  
Controlled Trials ◽  
Randomized Controlled ◽  
Parallel Group ◽  
Post Hoc

The Effect of Partly Missing Covariates on Statistical Power in Randomized Controlled Trials With Discrete-Time Survival Endpoints

Methodology ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 41-60
Author(s):  
Shahab Jolani ◽  
Maryam Safarkhani
Keyword(s):  
Randomized Controlled Trials ◽  
Discrete Time ◽  
Treatment Effect ◽  
Survival Data ◽  
Controlled Trials ◽  
Missing Covariates ◽  
Indicator Method ◽  
Imputation Methods ◽  
Randomized Controlled ◽  
Baseline Covariates

Abstract. In randomized controlled trials (RCTs), a common strategy to increase power to detect a treatment effect is adjustment for baseline covariates. However, adjustment with partly missing covariates, where complete cases are only used, is inefficient. We consider different alternatives in trials with discrete-time survival data, where subjects are measured in discrete-time intervals while they may experience an event at any point in time. The results of a Monte Carlo simulation study, as well as a case study of randomized trials in smokers with attention deficit hyperactivity disorder (ADHD), indicated that single and multiple imputation methods outperform the other methods and increase precision in estimating the treatment effect. Missing indicator method, which uses a dummy variable in the statistical model to indicate whether the value for that variable is missing and sets the same value to all missing values, is comparable to imputation methods. Nevertheless, the power level to detect the treatment effect based on missing indicator method is marginally lower than the imputation methods, particularly when the missingness depends on the outcome. In conclusion, it appears that imputation of partly missing (baseline) covariates should be preferred in the analysis of discrete-time survival data.

Comparing Performance of Methods to Deal With Differential Attrition in Randomized Experimental Evaluations

2021 ◽  
Vol 45 (1-2) ◽  
pp. 70-104
Author(s):  
Kaitlin Anderson ◽  
Gema Zamarro ◽  
Jennifer Steele ◽  
Trey Miller
Keyword(s):  
Randomized Controlled Trials ◽  
Research Design ◽  
Treatment Effect ◽  
Controlled Trials ◽  
Probability Weighting ◽  
Attrition Rates ◽  
Inverse Probability ◽  
Randomized Controlled ◽  
Two Samples ◽  
Weighting Methods

Background: In randomized controlled trials, attrition rates often differ by treatment status, jeopardizing causal inference. Inverse probability weighting methods and estimation of treatment effect bounds have been used to adjust for this bias. Objectives: We compare the performance of various methods within two samples, both generated through lottery-based randomization: one with considerable differential attrition and an augmented dataset with less problematic attrition. Research Design: We assess the performance of various correction methods within the dataset with problematic attrition. In addition, we conduct simulation analyses. Results: Within the more problematic dataset, we find the correction methods often performed poorly. Simulation analyses indicate that deviations from the underlying assumptions for bounding approaches damage the performance of estimated bounds. Conclusions: We recommend the verification of the underlying assumptions in attrition correction methods whenever possible and, when verification is not possible, using these methods with caution.

scholarly journals Is There Clinical Improvement Associated With Intradiscal Therapies? A Comparison Across Randomized Controlled Studies

2020 ◽  
pp. 219256822096305
Author(s):  
Derek G. Ju ◽  
Linda E. Kanim ◽  
Hyun W. Bae
Keyword(s):  
Stem Cells ◽  
Growth Factor ◽  
Randomized Controlled Trials ◽  
Fibrin Sealant ◽  
Controlled Trials ◽  
Single Center ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
Patient Reported ◽  
Post Hoc

Study Design: Post hoc comparison using single-site data from 4 multicenter randomized controlled trials. Objectives: Discogenic back pain is associated with significant morbidity and medical cost. Several terminated, unreported randomized controlled trials have studied the effect of intradiscal biologic injections. Here we report single-center outcomes from these trials to determine if there is clinical improvement associated with these intradiscal injections. Methods: Post hoc comparison was performed using single-site data from 4 similar multi-center randomized controlled trials. All trials evaluated an injectable therapy (growth factor, fibrin sealant, or stem cells) for symptomatic lumbar disc disease with near-identical inclusion and exclusion criteria. Demographics and patient reported outcomes were analyzed across treatment arms postinjection. Results: A total of 38 patients were treated with biologic agents and 12 were treated with control saline injections. There was a significant decrease in visual analogue score (VAS) pain for both the investigational and saline groups up to 12 months postinjection ( P < .01). There was no significant difference in VAS scores between the saline and investigational groups at 12 months. Similarly, there was significant improvement in patient-reported disability scores in both the investigational and saline groups at all time points. There were no significant differences in disability score improvement between the saline and investigational treatment groups at 12 months postinjection. Conclusions: A single-center analysis of 4 randomized controlled studies demonstrated no difference in outcomes between therapeutic intradiscal agents (growth factor, fibrin sealant, or stem cells) and control saline groups. In all groups, patient reported pain and disability scores decreased significantly. Future studies are needed to evaluate the therapeutic benefit of any intradiscal injections.

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