JSM 2004 - Toronto

Abstract #301502

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Activity Number: 156
Type: Contributed
Date/Time: Monday, August 9, 2004 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract - #301502
Title: Modeling LOCF Analysis of Continuous Endpoints in Clinical Trials
Author(s): Vijay Chauhan*+
Companies: NJ Biostatistics Inc.
Address: 21 Demarest Place, Piscataway, NJ, 08854,
Keywords: LOCF ; MMRM ; clinical trials ; study center
Abstract:

Analysis of LOCF endpoint is a standard procedure for evaluating treatments in clinical trials. A model with treatment and center effects is commonly used in multicenter trials. Sample size is calculated to ensure a power 80-90% for treatment comparisons with one LOCF observation per subject. However, the precision of other fixed effects namely the study center is ignored. If such fixed effects are not estimated precisely, the treatment effects may be biased. Rather than using the LOCF data only, we propose to use all data, which will allow more precise estimation of both treatment and center effects. We suggest classifying the observations as LOCF or non-LOCF, and estimating the treatment effects within this class along with the center effect in the model. The treatment effect estimated from LOCF class only may be used for inferences about efficacy at the final time point. Analysis of the data of a clinical trial showed that the standard errors of center and treatment effects were about 58% and 18% smaller, respectively. Simulation was performed to confirm the accuracy of this procedure.

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