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Understanding power in randomized trials: The example of vertebroplasty
J Eneling1, T E Darsaut2, C Veilleux3
1Department of radiology, service of neuroradiology, centre hospitalier de l'université de Montréal (CHUM), Montreal, Quebec, Canada.
Neuro-Chirurgie
|January 9, 2023
Summary
To avoid the "evidence of absence" fallacy in clinical trials, researchers should compare patient outcome proportions, not just average pain scores. This ensures trials adequately inform future medical care.
Area of Science:
- Clinical Trials Methodology
- Evidence-Based Medicine
Background:
- Randomized controlled trials (RCTs) require adequate sample sizes to reliably detect treatment effects or absence thereof.
- Current methods often rely on comparing means of continuous variables, potentially leading to underpowered trials.
Purpose of the Study:
- To evaluate the appropriateness of comparing means versus proportions in clinical trials for osteoporotic fractures.
- To determine optimal methods for sample size estimation and power maximization in RCTs.
Main Methods:
- Analysis of existing randomized controlled trials comparing vertebroplasty to placebo for osteoporotic fractures.
- Examination of statistical approaches used for sample size calculation and outcome assessment.
Main Results:
- Trials comparing means of continuous pain scores resulted in implausibly small sample sizes (e.g., 24 patients per group).
- Comparisons of means lack precise clinical meaning; proportion-based outcomes are more pertinent for patient care.
- Larger trials using proportion-based outcomes reduce the risk of the 'evidence of absence' fallacy.
Conclusions:
- Comparing the proportion of patients achieving a clinically meaningful outcome is superior to comparing means of continuous variables for informing medical care.
- Trial design should prioritize hard clinical outcomes like death and disability for robust evidence.
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