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.

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.