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. 2012 Apr;175(2):417-433.
doi: 10.1111/j.1467-985X.2011.00719.x. Epub 2011 Aug 4.

Joint modelling of longitudinal outcome and interval-censored competing risk dropout in a schizophrenia clinical trial

Ralitza Gueorguieva  1 , Robert Rosenheck, Haiqun Lin
Affiliations

Joint modelling of longitudinal outcome and interval-censored competing risk dropout in a schizophrenia clinical trial

Ralitza Gueorguieva et al. J R Stat Soc Ser A Stat Soc. 2012 Apr.

Abstract

The 'Clinical antipsychotic trials in intervention effectiveness' study, was designed to evaluate whether there were significant differences between several antipsychotic medications in effectiveness, tolerability, cost and quality of life of subjects with schizophrenia. Overall, 74 % of patients discontinued the study medication for various reasons before the end of 18 months in phase I of the study. When such a large percentage of study participants fail to complete the study schedule, it is not clear whether the apparent profile in effectiveness reflects genuine changes over time or is influenced by selection bias, with participants with worse (or better) outcome values being more likely to drop out or to discontinue. To assess the effect of dropouts for different reasons on inferences, we construct a joint model for the longitudinal outcome and cause-specific dropouts that allows for interval-censored dropout times. Incorporating the information regarding the cause of dropout improves inferences and provides better understanding of the association between cause-specific dropout and the outcome process. We use simulations to demonstrate the advantages of the joint modelling approach in terms of bias and efficiency.

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Figures

Fig. 1
Fig. 1
(a) Raw PANSS-means, (b) estimated PANSS-means based on separate PANSS-analysis and (c) estimated PANSS-means based on joint analysis of PANSS and different reasons for dropout in the CATIE study: formula image olanzapine; formula image quetiapine; formula image, risperidone; formula image, perphenazine
Fig. 2
Fig. 2
Cumulative incidence for dropout due to (a) inefficacy and (b) side effects in the CATIE study: formula image formula image olanzapine; quetiapine; formula image, risperidone; formula image, perphenazine
Fig. 3
Fig. 3
Estimated mean response for (a) treatment 0 in scenario 2, (b) treatment 1 in scenario 2, (c) treatment 0 in scenario 3 and (d) treatment 1 in scenario 3 of the simulation study: formula image, truth; formula image, joint model, separate dropout; formula image, joint model, common dropout; formula image, separate model
See this image and copyright information in PMC

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