Patient Health Questionnaire: Somatization Module (PHQ-15)

The Patient Health Questionnaire (PHQ) is an established self-assessment screening instrument for common mental disorders. The somatization module (PHQ-15) has 13 items and is used to diagnose somatoform disorders and to grade somatic complaints. Answers range from 0 (“not bothered at all”) to 2 (“bothered a lot”). Item 14 and 15 coincide with the PHQ-9. Cut-off values of 5, 10, and 15 serve to differentiate mild, moderate, and severe symptom levels, respectively [61]. In the validation study, Cronbach’s α was 0.80 [62]. In the German validation study, Cronbach’s α was found to be 0.79 [63]. In the present study, we obtained an internal consistency (Cronbach’s α) of 0.81 at T0 and 0.82 at T1. The questionnaire contains one item which is gender-specific for women (pain during menstruation or other menstruation problems). Women can therefore score higher than men. To equalize this condition, we calculated without the menstruation item (PHQ-15*).