Cited by 263Statistical Methods and Bayesian InferenceStatistical Methods in Clinical TrialsAdvanced Causal Inference Techniques

Handling drop‐out in longitudinal clinical trials: a comparison of the LOCF and MMRM approaches

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Lane, Peter·2008·Pharmaceutical Statistics

Abstract

This study compares two methods for handling missing data in longitudinal trials: one using the last‐observation‐carried‐forward (LOCF) method and one based on a multivariate or mixed model for repeated measurements (MMRM). Using data sets simulated to match six actual trials, I imposed several drop‐out mechanisms, and compared the methods in terms of bias in the treatment difference and power of the treatment comparison. With equal drop‐out in Active and Placebo arms, LOCF generally underestimated the treatment effect; but with unequal drop‐out, bias could be much larger and in either direction. In contrast, bias with the MMRM method was much smaller; and whereas MMRM rarely caused a difference in power of greater than 20%, LOCF caused a difference in power of greater than 20% in nearly half the simulations. Use of the LOCF method is therefore likely to misrepresent the results of a trial seriously, and so is not a good choice for primary analysis. In contrast, the MMRM method is unlikely to result in serious misinterpretation, unless the drop‐out mechanism is missing not at random (MNAR) and there is substantially unequal drop‐out. Moreover, MMRM is clearly more reliable and better grounded statistically. Neither method is capable of dealing on its own with trials involving MNAR drop‐out mechanisms, for which sensitivity analysis is needed using more complex methods. Copyright © 2007 John Wiley & Sons, Ltd.

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  • Linear mixed models analysis uses all available data and produces unbiased parameter estimates under the assumption of data being missing at random, making it suitable for intention-to-treat analyses in longitudinal studies with data missing at random.

    “Building on a likelihood-based approach, the linear mixed models analysis uses all available data and produces unbiased parameter estimates under the assumption of data being missing at random, making it suitable for intention-to-treat analyses in longitudinal studies with data missing at random [56-58].”

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  1. Mallinckrodt CH, Clark WS, David SR. Type I error rates from mixed effects model repeated measures compared with fixed effects ANOVA with missing values imputed via LOCF. Drug Informa- tion Journal 2001; 35:1214-1225.

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Authors
Lane, P.
Affiliations
GlaxoSmithKline (United Kingdom) (GB)
Corresponding author
Lane, Peter
Venue
Pharmaceutical Statistics
Publisher
Wiley
Published
2007-03-09
Volume
7
Issue
2
Pages
93-106
ISSN
  • 1539-1604 (ISSN-L)
  • 1539-1612
OpenAlex
W2068456795
Cited by
262
References
17
Citations by year
2026: 5 · 2025: 12 · 2024: 9 · 2023: 4 · 2022: 12 · 2021: 17 · 2020: 9 · 2019: 8 · 2018: 5 · 2017: 14 · 2016: 10 · 2015: 22 · 2014: 24 · 2013: 20 · 2012: 12
FWCI
17.61
Type
journal article
Language
en
Open access
Locations
  • Pharmaceutical Statistics (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
Keywords
dropout, missing data, last observation carried forward, bias in treatment effect estimation, statistical power, missing not at random, sensitivity analysis
MeSH terms
Clinical Trials as Topic, Computer Simulation, Data Interpretation, Statistical, Humans, Longitudinal Studies, Patient Dropouts, Bias, Multivariate Analysis

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