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. 2011 Jan 18;154(2):113-7.
doi: 10.7326/0003-4819-154-2-201101180-00010.

Addressing missing data in clinical trials

Thomas R Fleming  1
Affiliations

Addressing missing data in clinical trials

Thomas R Fleming. Ann Intern Med. .

Abstract

The reliability and interpretability of results from clinical trials can be substantially reduced by missing data. Frequently used approaches to address these concerns, such as upward adjustments in sample sizes or simplistic methods for handling missing data, including last-observation-carried-forward, complete-case, or worst-case analyses, are usually inadequate. Although rational imputation methods may be useful to treat missingness after it has occurred, these methods depend on untestable assumptions. Thus, the preferred and often only satisfactory approach to addressing missing data is to prevent it. Procedures should be in place to maximize the likelihood that outcome data will be obtained at scheduled times of evaluation for all surviving patients who have not withdrawn consent. To meaningfully reduce missing data, it is important to recognize and address many factors that commonly lead to higher levels of missingness.

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Conflict of interest statement

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M10-1856.

Figures

Figure
Figure. Change from baseline in 6-minute walk distance over 48 months after initiation of treatment in patients with pulmonary arterial hypertension
At each scheduled visit, the average change from baseline in 6-minute walk distance is plotted separately for the subgroups that will and will not remain under follow-up at the time of the next scheduled visit. The numbers above the squares represent, at each scheduled visit, the number of patients in the subgroup that will remain under follow-up at the time of the next scheduled visit. Hence, these are the numbers of patients who contribute to the calculations of the means and the 95% CIs for that subgroup.
See this image and copyright information in PMC

Comment in

  • Addressing missing data in clinical trials.
    van der Laan M, Lorenz TJ. van der Laan M, et al. Ann Intern Med. 2011 Jul 19;155(2):135. doi: 10.7326/0003-4819-155-2-201107190-00016. Ann Intern Med. 2011. PMID: 21768593 No abstract available.

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References

    1. Galiè N, Ghofrani HA, Torbicki A, Barst RJ, Rubin LJ, Badesch D, et al. Sildenafil Use in Pulmonary Arterial Hypertension (SUPER) Study Group. Sildenafil citrate therapy for pulmonary arterial hypertension. N Engl J Med. 2005;353:2148–57. - PubMed
    1. Lubsen J, Kirwan BA. Combined endpoints: can we use them? Stat Med. 2002;21:2959–70. - PubMed
    1. Lavori PW. Clinical trials in psychiatry: should protocol deviation censor patient data? Neuropsychopharmacology. 1992;6:39–48. - PubMed
    1. Peto R, Pike MC, Armitage P, Breslow NE, Cox DR, Howard SV, et al. Design and analysis of randomized clinical trials requiring prolonged observation of each patient. II. analysis and examples. Br J Cancer. 1977;35:1–39. - PMC - PubMed
    1. Pocock S. Clinical Trials: A Practical Approach. New York: J Wiley; 1983.

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