Development and evaluation of the Daily Assessment of Symptoms - Anxiety (DAS-A) scale to evaluate onset of symptom relief in patients with generalized anxiety disorder

Abstract

Background: Fast-acting anxiolytics are important to patients and society. Measuring early onset, however, requires a sensitive and clinically responsive measure. This study develops and evaluates the psychometric properties of a new patient-reported instrument, the Daily Assessment of Symptoms - Anxiety (DAS-A), designed to detect reduction of anxiety symptoms in patients with Generalized Anxiety Disorder (GAD) during the first week of treatment.

Methods: Clinician interviews and patient focus groups were conducted to identify relevant constructs; discussions focused on early symptom improvement and meaningful changes in GAD symptoms. The draft questionnaire underwent iterative sets of cognitive interviews to inform item reduction and revision. A double-blind, randomized, placebo-controlled study of paroxetine and lorazepam assessed the performance of the new instrument in GAD patients. Analyses evaluated the structure, reliability, validity, and utility of the instrument.

Results: There was consistency across focus groups and clinicians in the description of symptoms that improve first. The final item set was easily understood by interview participants. Factor analyses indicated that a unidimensional structure best described the data. Item-level descriptive statistics, Cronbach's alphas, effect sizes, and validity correlations with other scales were favorable. Most importantly, the DAS-A demonstrated separation of lorazepam from placebo within 24h of first dose and correlated with other anxiety measures.

Conclusions: This study resulted in the development of a reliable and valid instrument addressing the DSM-IV dimensions of GAD. The DAS-A is capable of detecting reduction in anxiety symptoms within 24h, making it a desirable measure to include in future trials of fast-acting anxiety medications.