Document Detail

Conclusion about the association between valve surgery and mortality in an infective endocarditis cohort changed after adjusting for survivor bias.
MedLine Citation:
PMID:  20122499     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Survivor bias commonly weakens observational studies, even those published in premier journals. It occurs because patients who live longer are more likely to receive treatment than those who die early. We sought to quantify the effect of survivor bias on the association between valve surgery and mortality in infective endocarditis (IE). STUDY DESIGN AND SETTING: The study cohort included 546 IE patients. We compared the hazard ratios (HR) resulting from two propensity score analysis approaches that adjusted for survivor bias (time-dependent variable and matching on follow-up time) with those achieved using the same models but without that adjustment (time-fixed variable). RESULTS: In the total cohort, the HR of surgery in the time-dependent model was 1.9 (95% confidence interval [CI] = 1.1-3.2; P = 0.03) vs. 0.9 (95% CI = 0.5-1.4; P = 0.53) in the time-fixed model. In the propensity score-matched subset, the HR of surgery was 1.3 (95% CI = 0.5-3.1; P = 0.56) and 0.8 (95% CI = 0.4-1.7; P = 0.57) in the subset with and without matching on follow-up time, respectively. CONCLUSION: Adjusting for survivor bias changed the conclusion about the association between valve surgery and mortality in IE. Researchers should be aware of this bias when evaluating observational studies of treatment efficacy.
Imad M Tleyjeh; Hassan M K Ghomrawi; James M Steckelberg; Victor M Montori; Tanya L Hoskin; Felicity Enders; W Charles Huskins; Farouk Mookadam; Walter R Wilson; Valerie Zimmerman; Larry M Baddour
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of clinical epidemiology     Volume:  63     ISSN:  1878-5921     ISO Abbreviation:  J Clin Epidemiol     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-02-03     Completed Date:  2010-04-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8801383     Medline TA:  J Clin Epidemiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  130-5     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier Inc. All rights reserved.
Division of Infectious Diseases, Department of Medicine, and Research Center, King Fahd Medical City, Riyadh, Saudi Arabia.
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MeSH Terms
Confounding Factors (Epidemiology)
Endocarditis / mortality,  surgery*
Epidemiologic Methods
Heart Valve Diseases / microbiology,  mortality,  surgery*
Middle Aged
Minnesota / epidemiology
Patient Selection
Selection Bias
Time Factors
Young Adult

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