LECTURE 19 2011

LECTURE 19 2011 - Missing Data in Clinical Trials Jims...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon
Missing Data in Clinical Trials
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Jim’s Latest Venture A Gourmet Health Food Spa
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Weight Loss Trial Results No. randomized 100 100 Weight change -15.0 -30.0 (12 months) Weight Watchers Jim’s Gourmet Spa Jim is very happy!
Background image of page 4
More Trial Results No. seen at 12 76/100 13/100 months Lost to Follow-up (%) 24% 87% Weight Watchers Jim’s Gourmet Spa
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Threats to the Interpretation of Clinical Trials Inadequately powered studies Surrogate markers and short follow-up Poor follow-up (missing data) Absence of pre-specified monitoring plans
Background image of page 6
Key Points Advantages of randomization are threatened when major outcomes are missing – no longer comparing like with like on average. Missing data can lead to biased estimates of treatment differences. Models for handling missing data involve unverifiable assumptions since reasons for missing data may not be known. Therefore, focus must be on preventing missing data (losses).
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
References National Research Council (2010). The prevention and treatment of missing data in clinical trials. Panel on Handling Missing Data in Clinical Trials. Committee on National Statistics. The National Academies Press Wood AM et al. Are missing outcome data adequately handled? A review of published randomized controlled trials in major medical journals. Clin Trials 2004; 1:368-376.n
Background image of page 8
Missing Data (definition) An outcome that is meaningful for analysis that was not collected. A participant who cannot be followed for a meaningful outcome is considered lost to follow-up for that outcome.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Reporting Missing Data in Clinical Trials 66% of 519 trials published in December 2000 did not report how they handled missing data. Of 71 trials published by the BMJ, JAMA, Lancet or N Engl J Med between July and December in 2001, 89% had partly missing outcome data. In 34 trials with repeated outcome measurements, 50% performed complete case analysis Only 21% reported sensitivity analysis. Lancet 2005 365: 1159-1162 and Clin Trials 2004; 1:368-376.
Background image of page 10
In order to carry out a proper intention-to-treat analysis all patients must be followed Intention-to-treat - an analysis which includes all randomized patients in the groups to which they were randomly assigned, regardless of their compliance with the entry criteria, regardless of the treatment they actually received, and regardless of subsequent withdrawal from treatment or deviation from protocol. Def: Fisher L, et al., 1990, in Peace et al. Statistical Issues in Drug Development , Mercel Dekker.
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
SMART Study Design Drug Conservation (DC) Strategy [Stop or defer ART until CD4+ < 250; then episodic ART based on CD4+ cell count to increase counts to > 350] Virologic Suppression (VS) Strategy [Continuous ART use] Participants with CD4 count > 350 n = 2720 n = 2752 N Engl J Med 2006
Background image of page 12
of SMART DC AIDS/death No AIDS/death 3000 VS 3000 6000 5090 910 What does “no” mean? DC = drug conservation (episodic ART)
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 14
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/21/2011 for the course PUBH 7420 taught by Professor Ph7420 during the Spring '07 term at Minnesota.

Page1 / 54

LECTURE 19 2011 - Missing Data in Clinical Trials Jims...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online