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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/2209

Title: Type I error rates from likelihood-based repeated measures analyses of incomplete longitudinal data
Authors: Mallinckrodt, Craig H.
Kaiser, Christopher J.
Watkin, John G.
Detke, Michael J.
Molenberghs, Geert
Carroll, Raymond J.
Issue Date: 2004
Citation: PHARMACEUTICAL STATISTICS, 3(3). p. 171-186
Abstract: The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood-based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood-based MAR approach - mixed-model repeated measures (MMRM) - compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Delta). Data emulating neuropsychiatric clinical trials were simulated in a 4 x 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Delta and SEDelta from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SEA from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SEDelta from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood-based MA R approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright (C) 2004 John Wiley Sons Ltd.
Notes: Eli Lilly & Co, Lilly Corp Ctr, Indianapolis, IN 46285 USA. Harvard Univ, Sch Med, Dept Psychiat, Boston, MA 02115 USA. McLean Hosp, Belmont, MA 02178 USA. Indiana Univ Sch Med, Indianapolis, IN USA. Limburgs Univ Ctr, Ctr Stat, Diepenbeek, Belgium. Texas A&M Univ, Dept Stat, College Stn, TX 77843 USA.Mallinckrodt, CH, Eli Lilly & Co, Lilly Corp Ctr, Indianapolis, IN 46285 USA.cmallinc@lilly.com
URI: http://hdl.handle.net/1942/2209
DOI: 10.1002/pst.131
ISI #: 000224261600003
ISSN: 1539-1604
Category: A1
Type: Journal Contribution
Validation: ecoom, 2005
Appears in Collections: Research publications

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