Understanding the relationships between health outcomes in generalized anxiety disorder clinical trials
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- Wyrwich, K.W., Harnam, N., Locklear, J.C. et al. Qual Life Res (2011) 20: 255. doi:10.1007/s11136-010-9734-1
Background and Aims
The Wilson–Cleary health outcomes model is a hypothesized pathway linking traditional clinical variables to health-related quality of life (HRQL). This study tested the application of the Wilson–Cleary model to a patient population with generalized anxiety disorder (GAD) using longitudinal clinical trial data.
These secondary analyses pooled data from three similar 8-week, placebo-controlled, double-blind, randomized, multicenter trials of quetiapine XR therapy in GAD. Relevant health assessments for the model concepts included the Clinical Global Impression-Severity of Illness, Hamilton Rating Scale for Anxiety, the Pittsburgh Sleep Quality Index and Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form. A lagged path model tested whether the hypothesized relationships at baseline and week 8 between the concepts of the adapted Wilson–Cleary model were consistent with the observed data.
The resulting model fit the data (RMSEA = 0.077; CFI = 0.98; NFI = 0.96) and explained 56% of the variance in overall quality of life assessment at baseline and 69% of the variance in this assessment at week 8. Moderate to strong relationships between the adjacent hypothesized concepts support the specified model.
This adapted Wilson–Cleary model for health outcomes validated in GAD should improve the understanding and usefulness of health status measurements in this condition and increase the applications of this model to other clinical trial data.