Psychometric evaluation of a patient-rated troubling symptom scale for generalized anxiety disorder clinical trials.
Johnson & Johnson Pharmaceutical Research & Development, Titusville, NJ.
Background: The majority of clinical outcome assessments developed for generalized anxiety disorder (GAD) may not efficiently and sensitively reflect heterogeneous symptom clusters from a patient perspective. The Patient-Rated Troubling Symptoms Scale for Anxiety (PaRTS-A) instrument was developed to provide an individualized assessment of patient relevant GAD symptoms. Objective: The objective of this analysis was to evaluate the psychometric characteristics of the PaRTS-A. Methods: Data were taken from a 6-week clinical trial evaluating the efficacy of adjunctive risperidone therapy in GAD patients undergoing standard treatment. Patients completed the PaRTS-A, the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q), and the Sheehan Disability Scale (SDS) as well as impressions of improvement. Physicians completed the Hamilton Anxiety Rating Scale (HAM-A). A instrument characteristics were assessed through statistical tests of reliability, reproducibility, construct and discriminant validity, and responsiveness. Results: In the item response theory (IRT) analysis, the PaRTS-A items fit into a single construct of anxiety. Internal consistency reliability exceeded 0.70. The PaRTS-A total score was moderately correlated with the Q-LES-Q and the SDS. The PaRTS-A distinguished between patients with high and low HAM-A scores (p<0.001). The PaRTS-A was responsive to changes in clinical status and the minimal important difference was identified. Conclusion: The PaRTS-A provides a unique patient-rated assessment of anxiety symptoms. The instrument may provide clinicians with useful information regarding patient's self-rated anxiety disorder symptoms and the hierarchy of symptoms that they considered most troubling. Our analysis suggests that the PaRTS-A is an internally consistent, valid, and responsive instrument that may be a beneficial adjunct to other instruments in clinical trials.
PMID: 18779777 [PubMed - in process]