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Related Concept Videos

Clinical Trials: Overview01:11

Clinical Trials: Overview

Clinical development focuses on how the drug will interact with the human body and encompasses four key phases of clinical trials, each serving a specific purpose in assessing the safety and effectiveness of new drugs. These phases overlap and build upon one another. Phase I involves a small group of healthy volunteers (typically 20-80 individuals) or, in cases where significant toxicity is expected, patients with the targeted disease, such as cancer or AIDS. The volunteers are tested for...
Clinical Trials01:16

Clinical Trials

Clinical trials are prospective experimental studies conducted on humans to determine the safety and efficacy of treatments, drugs, diet methods, and medical devices. Using statistics in clinical trials enables researchers to derive reasonable and accurate conclusions from the collected data, allowing them to make wise decisions in uncertain situations. In medical research, statistical methods are crucial for preventing errors and bias.
There are four phases in a clinical trial. A phase one...
Comparing the Survival Analysis of Two or More Groups01:20

Comparing the Survival Analysis of Two or More Groups

Survival analysis is a cornerstone of medical research, used to evaluate the time until an event of interest occurs, such as death, disease recurrence, or recovery. Unlike standard statistical methods, survival analysis is particularly adept at handling censored data—instances where the event has not occurred for some participants by the end of the study or remains unobserved. To address these unique challenges, specialized techniques like the Kaplan-Meier estimator, log-rank test, and Cox...
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches01:23

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

Biopharmaceutical studies constitute a vital field aiming to enhance drug delivery methods and refine therapeutic approaches, drawing upon diverse interdisciplinary knowledge. In research methodologies, the choice between controlled and non-controlled studies significantly influences the study's reliability and accuracy.
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast, controlled...
Assumptions of Survival Analysis01:15

Assumptions of Survival Analysis

Survival models analyze the time until one or more events occur, such as death in biological organisms or failure in mechanical systems. These models are widely used across fields like medicine, biology, engineering, and public health to study time-to-event phenomena. To ensure accurate results, survival analysis relies on key assumptions and careful study design.
Preclinical Development: Overview01:28

Preclinical Development: Overview

Preclinical development consists of a series of tests that ensure the safety and efficacy of a new therapeutic compound before it is tested in humans. There are four main phases to this process. First, safety pharmacology tests are conducted to ensure the drug does not produce any acutely harmful effects. These tests examine parameters such as bronchoconstriction, cardiac dysrhythmias, blood pressure changes, and ataxia. Next, preliminary toxicological testing is performed to determine the...

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Related Experiment Video

Updated: May 8, 2026

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition
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A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

Published on: September 20, 2019

Optimal timing for interim analyses in clinical trials.

Kanae Togo1, Manabu Iwasaki

  • 1Clinical Statistics, Pfizer Japan, Inc., Tokyo, Japan. kanae.togo@pfizer.com

Journal of Biopharmaceutical Statistics
|August 21, 2013
PubMed
Summary
This summary is machine-generated.

Optimizing clinical trial interim analyses minimizes expected sample size. Early termination is best around two-thirds or half-way for O

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Area of Science:

  • Clinical Trial Design
  • Biostatistics
  • Statistical Analysis

Background:

  • Interim analyses are crucial in clinical trials for early termination or sample size adjustment.
  • The timing of interim analyses significantly impacts trial duration and subject enrollment.
  • Minimizing the expected total sample size is a key objective in clinical trial design.

Purpose of the Study:

  • To determine the optimal timing for conducting interim analyses to minimize expected total sample size.
  • To evaluate the impact of enrollment status (halted vs. continuous) on optimal interim analysis timing.
  • To explore the role of sample size adjustment in conjunction with interim analyses.

Main Methods:

  • Statistical modeling to analyze the effect of interim analysis timing on expected sample size.
  • Examination of different spending functions (O'Brien-Fleming, Pocock) for interim analyses.
  • Simulation or theoretical analysis considering both halted and continuous subject enrollment scenarios.

Main Results:

  • For early termination, optimal interim analysis timing is ~2/3 for O'Brien-Fleming and ~1/2 for Pocock spending functions when enrollment halts.
  • When enrollment is continuous, optimal timing depends on follow-up duration.
  • The study provides optimal time recommendations for single interim analyses, considering sample size adjustments.

Conclusions:

  • Strategic timing of interim analyses is essential for efficient clinical trial resource allocation.
  • The optimal time for interim analysis is influenced by the chosen statistical method and enrollment strategy.
  • Findings offer practical guidance for optimizing clinical trial design to reduce overall sample size.