Abstract #300399

This is the preliminary program for the 2003 Joint Statistical Meetings in San Francisco, California. Currently included in this program is the "technical" program, schedule of invited, topic contributed, regular contributed and poster sessions; Continuing Education courses (August 2-5, 2003); and Committee and Business Meetings. This on-line program will be updated frequently to reflect the most current revisions.

To View the Program:
You may choose to view all activities of the program or just parts of it at any one time. All activities are arranged by date and time.

The views expressed here are those of the individual authors
and not necessarily those of the ASA or its board, officers, or staff.

Back to main JSM 2003 Program page
JSM 2003 Abstract #300399
Activity Number: 247
Type: Contributed
Date/Time: Tuesday, August 5, 2003 : 10:30 AM to 12:20 PM
Sponsor: Biopharmaceutical Section
Abstract - #300399
Title: Analysis of Immune Responses in Vaccine Clinical Trials with a Pre-Post Design
Author(s): Bill Wang*+ and David J. Li and Guanghan (Frank) Liu and Ivan Siu Fung Chan
Companies: Merck & Co., Inc. and Merck Research Laboratories and Merck Research Laboratories and Merck Research Laboratories
Address: 785 Jolly Rd, Bldg. C, Blue Bell, PA, 19422,
Keywords: missing baseline ; ANCOVA ; repeated measure ; vaccine clinical trial ; immunogenicity
Abstract:

Clinical assays are frequently used as biomarkers to measure the immune responses in vaccine clinical trials with a pre-post design. The treatment effect is often estimated using the analysis of covariance (ANCOVA) model, accounting for the level of immunity at prevaccination as a covariate. However, due to many unexpected problems in sample collection, storage, shipment, and testing, assay values could be missing. In order to overcome the difficulty of using the ANCOVA model when some prevaccination assay values are missing, we investigated alternative approaches that include a saturated repeated measure model, a restricted repeated measure model (Liang and Zeger 2000), and a multiple imputation approach. Extensive simulations were performed to compare these approaches in terms of estimation bias, study power, and Type I error rate. Based on these simulations, we recommend the restricted repeated measure approach as the method of choice.

  • The address information is for the authors that have a + after their name.
  • Authors who are presenting talks have a * after their name.

Back to the full JSM 2003 program

JSM 2003 For information, contact meetings@amstat.org or phone (703) 684-1221. If you have questions about the Continuing Education program, please contact the Education Department.
Revised March 2003