Effect of dropouts in a longitudinal study: an application of a repeated ordinal model.
An analysis is presented of a longitudinal study of fluvoxamine, an antidepressant drug, with ordinal responses, regressed on a combination of discrete and continuous covariates and with a substantial proportion of dropouts. Classical methods, such as weighted least squares (SAS procedure CATMOD) and logistic regression, are not suitable for the analysis of such data. Instead, we illustrate how a recently introduced model can be used to solve most of the problems posed. The method is likelihood-based and is an extension of the bivariate Dale model to an arbitrary number of outcomes. The method is suitable for several types of designs commonly employed in clinical trials.
Lesaffre
E
E
Catholic University Leuven, Belgium.
Molenberghs
G
G
Dewulf
L
L
D018687:Antidepressive Agents, Second-Generation / Q000009:adverse effects / Q000627:therapeutic use; D001008:Anxiety Disorders / Q000188:drug therapy; D003627:Data Interpretation, Statistical; D003863:Depression / Q000188:drug therapy; D016666:Fluvoxamine / Q000009:adverse effects / Q000627:therapeutic use; D006801:Humans; D016013:Likelihood Functions; D008137:Longitudinal Studies; D015233:Models, Statistical; D010352:Patient Dropouts
D018687:Antidepressive Agents, Second-Generation; D016666:Fluvoxamine