Document Detail

Age-dependent U-shaped risk functions and Aalen's additive risk model.
MedLine Citation:
PMID:  9750247     Owner:  NLM     Status:  MEDLINE    
Epidemiologic studies of time to some failure often show a quadratic relation between the risk of failure and covariate(s). We study the nadir for a given covariate, i.e., the value of the covariate associated with the lowest risk (supposing a U-shape), within Aalen's additive risk model. This model was applied since the effect of the covariate(s) is allowed to vary over time and, as a consequence, a given nadir can vary over time. We propose a test for the null hypothesis that the nadir is time independent and, if this is the case, an estimate of the nadir. Large sample properties of the test statistic and estimator are derived. The methods are illustrated with data where time to death is related to body mass index.
T Martinussen; T I Sørensen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biometrics     Volume:  54     ISSN:  0006-341X     ISO Abbreviation:  Biometrics     Publication Date:  1998 Sep 
Date Detail:
Created Date:  1998-11-03     Completed Date:  1998-11-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370625     Medline TA:  Biometrics     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  989-1001     Citation Subset:  IM    
Department of Biostatistics, University of Copenhagen, Denmark.
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MeSH Terms
Age Factors
Aged, 80 and over
Biometry / methods*
Body Mass Index
Epidemiologic Factors
Middle Aged
Models, Statistical*
Obesity / mortality,  pathology
Proportional Hazards Models
Risk Factors

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