Validity of the Greek version of the PHQ 15-item Somatic Symptom Severity Scale in patients with chronic medical conditions and correlations with emergency department use and illness perceptions.

BACKGROUND: The PHQ-15 is a brief measure assessing the severity of somatic symptoms and is widely used in different health care settings. We aimed to assess the psychometric properties of its Greek version in patients with chronic physical illnesses seeking urgent or unscheduled care in the Accident and Emergency Department (AED). METHODS: The PHQ-15 was translated into Greek using back-translation, and it was administered to 303 patients with diabetes, COPD and rheumatic diseases visiting our AED during a one-year period. Patients were interviewed with the MINI. Depressive (PHQ-9) and somatization symptoms (SCL-12), illness perceptions (B-IPQ) and health-related quality of life (WHOQOL-BREF) were also assessed to test criterion and concurrent validity. RESULTS: The Greek version of the PHQ-15 showed acceptable internal consistency. Convergent validity was established by the strong associations observed between PHQ-15 scores and functional status, depressive symptom severity and AED visits during the previous year. PHQ-15 scores were also associated with the patients' concerns about personal and treatment illness's control and their beliefs regarding the number of bodily symptoms attributed to their illness (illness identity). The highly acceptable convergent and discriminant validity of the five individual bodily symptoms assessed by both the PHQ-15 and SCL-12 is a further construct validity indicator. CONCLUSIONS: The present findings support the applicability of the Greek version of PHQ-15 in assessing common somatic symptoms either medically explained or unexplained in patients seeking care in the AED, further confirming that it can be considered suitable for use in a broad range of populations in clinical research.