Analysing covariates with spike at zero

• Verfasst von: Becher, Heiko [VerfasserIn]
• Verfasst von: Lorenz, Eva [VerfasserIn]
• Verfasst von: Royston, Patrick [VerfasserIn]
• Verfasst von: Sauerbrei, Wilhelm F. [VerfasserIn]
• Titel: Analysing covariates with spike at zero
• Titelzusatz: a modified FP procedure and conceptual issues
• Ausgabe: First published: 09 July 2012
• E-Jahr: 2012
• Jahr: September 2012
• Umfang: 15 S.
• Fussnoten: Gesehen am 16.11.2018
• Titel Quelle: Enthalten in: Biometrical journal
• Ort Quelle: Berlin : Wiley-VCH, 1977
• Jahr Quelle: 2012
• Band/Heft Quelle: 54(2012), 5, Seite 686-700
• ISSN Quelle: 1521-4036
• DOI: doi:10.1002/bimj.201100263
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Dose-response model
• Sach-SW: Fraction unexposed
• Sach-SW: Fractional polynomials
• Sach-SW: Regression modelling
• K10plus-PPN: 1583764240

Abstract

In epidemiology and in clinical research, risk factors often have special distributions. A common situation is that a proportion of individuals have exposure zero, and among those exposed, we have some continuous distribution. We call this a 'spike at zero'. Examples for this are smoking, duration of breastfeeding, or alcohol consumption. Furthermore, the empirical distribution of laboratory values and other measurements may have a semi-continuous distribution as a result of the lower detection limit of the measurement. To model the dose-response function, an extension of the fractional polynomial approach was recently proposed. In this paper, we suggest a modification of the previously suggested FP procedure. We first give the theoretical justification of this modified procedure by investigating relevant distribution classes. Here, we systematically derive the theoretical shapes of dose-response curves under given distributional assumptions (normal, log normal, gamma) in the framework of a logistic regression model. Further, we check the performance of the procedure in a simulation study and compare it to the previously suggested method, and finally we illustrate the procedures with data from a case-control study on breast cancer.