Prevalence of Generalized Anxiety Disorder in Psychiatric Outpatients (PRADO Study): A Multicenter Cross-Sectional Study in Japan

Purpose: Generalized anxiety disorder (GAD) impairs quality of life (QoL) and daily function; however, it remains under-recognized in Japan due to symptom overlap and a lack of approved treatments. This study estimated GAD prevalence among psychiatric outpatients using the Structured Clinical Interview for DSM (SCID), examined associated demographic and clinical factors, assessed health status and QoL, and evaluated the diagnostic validity of the Generalized Anxiety Disorder 7-item scale (GAD-7) and the Kessler 6-item Psychological Distress scale (K6) versus SCID. Methods: This multicenter, cross-sectional study analyzed 407 patients across 22 sites. Prevalence was determined through SCID-based structured interviews. Demographics were obtained from paper questionnaires and clinical characteristics from medical records. Patient-reported outcomes quantified burden and screening accuracy. Results: Eighty-three of 407 patients (20.4%) met DSM-5 criteria for GAD using SCID. Prevalence was higher in females versus males (68.7% vs 31.3%) and more common among younger individuals. Comorbid depressive disorders were frequent (63.4%), with major depressive disorder being the most prevalent. Patients with GAD were more likely to have lower income, be students, and exhibit higher symptom severity on both the Quick Inventory of Depressive Symptomatology Self-Report (QIDS-SR) and the GAD-7. Patients with GAD (n=83) had higher QIDS-SR, GAD-7, and K6 scores than non-GAD patients, indicating greater depressive symptoms, anxiety, and psychological distress. Health-related QoL and functional impairment measured through EuroQol 5 Dimensions 5 Levels and the Sheehan Disability Scale indicated worse outcomes in GAD. GAD-7 and K6 demonstrated moderate diagnostic performance versus SCID. Conclusion: GAD was prevalent among Japanese psychiatric outpatients (20.4%), suggesting the potential under-recognition in clinical practice, with some patients receiving alternative diagnoses. The lack of approved treatments and recognized diagnostic procedures may exacerbate the patient’s burden. Developing GAD-specific therapies and improving diagnostic awareness are critical to addressing this unmet need. Keywords: generalized anxiety disorder, Japan, prevalence, DSM-5, structured interview, PRO