Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2009 Jun 11:10:40.
doi: 10.1186/1745-6215-10-40.

LOST to follow-up Information in Trials (LOST-IT): a protocol on the potential impact

Elie A Akl  1 , Matthias Briel, John J You, Francois Lamontagne, Azim Gangji, Tali Cukierman-Yaffe, Mohamad Alshurafa, Xin Sun, Kara A Nerenberg, Bradley C Johnston, Claudio Vera, Edward J Mills, Dirk Bassler, Arturo Salazar, Neera Bhatnagar, Jason W Busse, Zara Khalid, Sd Walter, Deborah J Cook, Holger J Schünemann, Douglas G Altman, Gordon H Guyatt
Affiliations

LOST to follow-up Information in Trials (LOST-IT): a protocol on the potential impact

Elie A Akl et al. Trials. .

Abstract

Background: Incomplete ascertainment of outcomes in randomized controlled trials (RCTs) is likely to bias final study results if reasons for unavailability of patient data are associated with the outcome of interest. The primary objective of this study is to assess the potential impact of loss to follow-up on the estimates of treatment effect. The secondary objectives are to describe, for published RCTs, (1) the reporting of loss to follow-up information, (2) the analytic methods used for handling loss to follow-up information, and (3) the extent of reported loss to follow-up.

Methods: We will conduct a systematic review of reports of RCTs recently published in five top general medical journals. Eligible RCTs will demonstrate statistically significant effect estimates with respect to primary outcomes that are patient-important and expressed as binary data. Teams of 2 reviewers will independently determine eligibility and extract relevant information from each eligible trial using standardized, pre-piloted forms. To assess the potential impact of loss to follow-up on the estimates of treatment effect we will, for varying assumptions about the outcomes of participants lost to follow-up (LTFU), calculate (1) the percentage of RCTs that lose statistical significance and (2) the mean change in effect estimate across RCTs. The different assumptions we will test are the following: (1) none of the LTFU participants had the event; (2) all LTFU participants had the event; (3) all LTFU participants in the treatment group had the event; none of those in the control group had it (worst case scenario); (4) the event incidence among LTFU participants (relative to observed participants) increased, with a higher relative increase in the intervention group; and (5) the event incidence among LTFU participants (relative to observed participants) increased in the intervention group and decreased in the control group.

Discussion: We aim to make our objectives and methods transparent. The results of this study may have important implications for both clinical trialists and users of the medical literature.

PubMed Disclaimer

Figures

Figure 1
Figure 1
LOST-IT framework illustrating issues related to loss-to-follow-up and threats to validity for binary outcomes.
See this image and copyright information in PMC

References

    1. Montori VM, Guyatt GH. Intention-to-treat principle. 2001;165:1339–1341. - PMC - PubMed
    1. Altman DG. Missing outcomes: addressing the dilemma. Open Med. 2009;3:e21–e23. - PMC - PubMed
    1. Fielding S, Maclennan G, Cook JA, Ramsay CR. A review of RCTs in four medical journals to assess the use of imputation to overcome missing data in quality of life outcomes. Trials. 2008;9:51. doi: 10.1186/1745-6215-9-51. - DOI - PMC - PubMed
    1. Moher D, Schulz KF, Altman D, for the CG The CONSORT Statement: Revised Recommendations for Improving the Quality of Reports of Parallel-Group Randomized Trials. JAMA. 2001;285:1987–1991. doi: 10.1001/jama.285.15.1987. - DOI - PubMed
    1. Altman DG, Schulz KF, Moher D, Egger M, Davidoff F, Elbourne D, Gotzsche PC, Lang T, for the CG The Revised CONSORT Statement for Reporting Randomized Trials: Explanation and Elaboration. Ann Intern Med. 2001;134:663–694. - PubMed

Publication types

LinkOut - more resources