Structural validity of the Anxiety Symptom Scale - a Danish validation study

Area of Science:

• Psychiatry
• Psychometrics
• General Practice

Background:

• The Anxiety Symptom Scale (ASS) is a 10-item psychometric tool used for anxiety screening in Danish general practice.
• It comprises nine anxiety symptom items and one functional impairment item.
• Prior research suggested potential benefits from reducing response categories and its unidimensionality.

Purpose of the Study:

• To evaluate a modified ASS with fewer response categories.
• To compare the psychometric structure of the original and modified ASS versions.
• To assess the ASS's utility as a unidimensional measure of global anxiety and its correlation with functional impairment.

Main Methods:

• A modified version of the ASS with reduced response categories was created.
• The original and modified ASS versions were compared using a bifactor model.
• Respondents were recruited from general practice consultations, mental health associations, and a general practice waiting room.

Main Results:

• The original ASS version demonstrated a better fit to the bifactor model than the modified version.
• The bifactor model indicated that the ASS primarily measures a single underlying trait (global anxiety).
• The general factor strongly predicted functional impairment.

Conclusions:

• The first nine items of the ASS serve as a unidimensional measure of global anxiety, correlating significantly with functional impairment.
• The ASS is valuable for general practitioners in initial treatment decision-making.
• Reducing response categories or removing a specific item did not enhance the instrument's performance.