On dichotomizing phenotypes in family-based association tests: quantitative phenotypes are not always the optimal choice.

Full Abstract

In family-based association studies, quantitative traits are thought to provide higher statistical power than dichotomous traits. Consequently, it is standard practice to collect quantitative traits and to analyze them as such. However, in many situations, continuous measurements are more difficult to obtain and/or need to be adjusted for other factors/confounding variables which also have to be measured. In such scenarios, it can be advantageous to record and analyze a "simplified/dichotomized" version of the original trait. Under fairly general circumstances, we derive here rules for the dichotomization of quantitative traits that maintain power levels that are comparable to the analysis of the original quantitative trait. Using simulation studies, we show that the proposed rules are robust against phenotypic misclassification, making them an ideal tool for inexpensive phenotyping in large-scale studies. The guidelines are illustrated by an application to an asthma study.Copyright 2007 Wiley-Liss, Inc.

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Author information

Author/s: Fardo, David (D); Celedón, Juan C (JC); Raby, Benjamin A (BA); Weiss, Scott T (ST); Lange, Christoph (C);

Affiliation: Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA. dfardo(-atsign-)hsph.farvard.edu

Grants: 5 R01 MH059532 (Agency:NIMH NIH HHS) ; 5 T32 HL07427-26 (Agency:NHLBI NIH HHS) ; N01-HR-16049 (Agency:NHLBI NIH HHS) ; T90 DK070078 (Agency:NIDDK NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural

Journal: Genetic epidemiology (Genet Epidemiol), published in United States. (Language: eng)

Reference: 2007-Jul; vol 31 (issue 5) : pp 376-82

Dates: Created 2007/06/28; Completed 2007/08/06; Revised 2007/12/03;

PMID: 17342772, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Alleles
Asthma - genetics; physiopathology
Child
Family
Female
Forced Expiratory Volume
Gene Frequency
Genetic Predisposition to Disease

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