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A simulation study comparing slope model with mixed-model repeated measure to assess cognitive data in clinical trials of Alzheimer's disease.

ABSTRACT: Introduction:In clinical trials of Alzheimer's disease, a mixed-model repeated measure approach often serves as the primary analysis when evaluating disease progression; a slope model may be secondary. Methods:Longitudinal change from baseline (14-item version of Alzheimer's Disease Assessment Scale-Cognitive Subscale) was simulated for treatment/placebo from multivariate normal distributions with the variance-covariance matrix estimated from solanezumab trial data. Type I error, power, and bias were based on 18-month treatment contrast. Sample sizes included 500 and 1000 patients/arm. Results:The slope model was more powerful in most scenarios. Mixed-model repeated measure was relatively unbiased in parameter estimation. The slope model yielded unbiased estimates whenever the underlying trajectory was not detectably different from linear. Both methods led to similar type I error. Discussion:In clinical trials of Alzheimer's disease, mixed-model repeated measure analysis with relaxed assumptions on disease progression seems to be preferred. The slope model might be more powerful if the trajectory has little departure from linearity.

SUBMITTER: Chen YF

PROVIDER: S-EPMC6021263 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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A simulation study comparing slope model with mixed-model repeated measure to assess cognitive data in clinical trials of Alzheimer's disease.

Chen Yun-Fei YF Ni Xiao X Fleisher Adam S AS Zhou Wei W Aisen Paul P Mohs Richard R

Alzheimer's & dementia (New York, N. Y.) 20180118

<h4>Introduction</h4>In clinical trials of Alzheimer's disease, a mixed-model repeated measure approach often serves as the primary analysis when evaluating disease progression; a slope model may be secondary.<h4>Methods</h4>Longitudinal change from baseline (14-item version of Alzheimer's Disease Assessment Scale-Cognitive Subscale) was simulated for treatment/placebo from multivariate normal distributions with the variance-covariance matrix estimated from solanezumab trial data. Type I error, ...[more]

PMID: 29955651

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Project description:Most Alzheimer's disease (AD) clinical trials enroll participants multinationally. Yet, few data exist to guide investigators and sponsors regarding the types of patients enrolled in these studies and whether participant characteristics vary by region.We used data derived from four multinational phase III trials in mild to moderate AD to examine whether regional differences exist with regard to participant demographics, safety reporting, and baseline scores on the Mini Mental State Examination (MMSE), the 11-item Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-cog11), the Clinical Dementia Rating scale Sum of Boxes (CDR-SB), the Alzheimer's Disease Cooperative Study-Activities of Daily Living Inventory (ADCS-ADL), and the Neuropsychiatric Inventory (NPI). We assigned 31 participating nations to 7 geographic regions: North America, South America/Mexico, Western Europe/Israel, Eastern Europe/Russia, Australia/South Africa, Asia, and Japan.North America, Western Europe/Israel, and Australia/South Africa enrolled similar proportions of men, apolipoprotein E ?4 carriers, and participants with spouse study partners, whereas Asia, Eastern Europe/Russia, and South America/Mexico had lower proportions for these variables. North America and South America/Mexico enrolled older subjects, whereas Asia and South America/Mexico enrolled less-educated participants than the remaining regions. Approved AD therapy use differed among regions (range: 73% to 92%) and was highest in North America, Western Europe/Israel, and Japan. Dual therapy was most frequent in North America (48%). On the MMSE, North America, Western Europe/Israel, Japan, and Australia/South Africa had higher (better) scores, and Asia, South America/Mexico, and Eastern Europe/Russia had lower scores. Eastern Europe/Russia had more impaired ADAS-cog11 scores than all other regions. Eastern Europe/Russia and South America/Mexico had more impaired scores for the ADCS-ADL and the CDR-SB. Mean scores for the CDR-SB in Asia were milder than all regions except Japan. NPI scores were lower in Asia and Japan than in all other regions. Participants in North America and Western Europe/Israel reported more adverse events than those in Eastern Europe/Russia and Japan.These findings suggest that trial populations differ across geographic regions on most baseline characteristics and that multinational enrollment is associated with sample heterogeneity. The data provide initial guidance with regard to the regional differences that contribute to this heterogeneity and are important to consider when planning global trials.

Project description:Surfactant Replacement Therapy (SRT), which involves instillation of a liquid-surfactant mixture directly into the lung airway tree, is a major therapeutic treatment in neonatal patients with respiratory distress syndrome (RDS). This procedure has proved to be remarkably effective in premature newborns, inducing a five-fold decrease of mortality in the past 35 years. Disappointingly, its use in adults for treating acute respiratory distress syndrome (ARDS) experienced initial success followed by failures. Our recently developed numerical model has demonstrated that transition from success to failure of SRT in adults could, in fact, have a fluid mechanical origin that is potentially reversible. Here, we present the first numerical simulations of surfactant delivery into a realistic asymmetric conducting airway tree of the rat lung and compare them with experimental results. The roles of dose volume (VD), flow rate, and multiple aliquot delivery are investigated. We find that our simulations of surfactant delivery in rat lungs are in good agreement with our experimental data. In particular, we show that the monopodial architecture of the rat airway tree plays a major role in surfactant delivery, contributing to the poor homogeneity of the end distribution of surfactant. In addition, we observe that increasing VD increases the amount of surfactant delivered to the acini after losing a portion to coating the involved airways, the coating cost volume, VCC. Finally, we quantitatively assess the improvement resulting from a multiple aliquot delivery, a method sometimes employed clinically, and find that a much larger fraction of surfactant reaches the alveolar regions in this case. This is the first direct qualitative and quantitative comparison of our numerical model with experimental studies, which enhances our previous predictions in adults and neonates while providing a tool for predicting, engineering, and optimizing patient-specific surfactant delivery in complex situations.

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A simulation study comparing slope model with mixed-model repeated measure to assess cognitive data in clinical trials of Alzheimer's disease.

Publications

A simulation study comparing slope model with mixed-model repeated measure to assess cognitive data in clinical trials of Alzheimer's disease.

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