Validation of the Spanish version of the PHQ-15 questionnaire for the evaluation of physical symptoms in patients with depression and/or anxiety disorders: DEPRE-SOMA study.

OBJECTIVE: This work has aimed to validate the Spanish version of the PHQ-15 questionnaire (Patient Health Questionnaire) for its use in patients with depression and/or and anxiety disorders.
MATERIAL AND METHODS: An observational, cross-sectional study in which the PHQ-15 questionnaire (made up of 15 items on somatic symptoms) was administered in the outpatient psychiatric clinics to patients of 18 years or more, diagnosed of depression and/or anxiety disorder according to the DSM-IV criteria. Feasibility (percent of patients without response), reliability (in terms of internal consistency) and convergent/divergent validity compared to the MADRS scale (by correlational analysis), discriminant (with intragroup comparison) and predictive (by logistical regression).
RESULTS: A total of 3362 evaluated patients were included. Of these, 65.5% were women, with a mean age of 45.6 years (18.0-90.0). The questionnaire was feasible (9.6% of patients lacking an answer to some item), and showed acceptable internal reliability (Cronbach's Alpha Coefficient =0.78) with adequate validity, with correlations with the MADRS scale between moderate and high (r=0.3-0.7) and differences between groups of patients. The factors associated to the profile type of the patient with relevant physical symptoms were: being a woman, having a background of depression and/or anxiety, anxiety according to the DSM-IV, any concomitant condition in general, and specifically hepatic-digestive and osteoarticular system affectation and, as protective factor, being 70 years of age or older.
CONCLUSION: The PHQ-15 questionnaire in its Spanish version has been shown to be feasible, reliable and valid to evaluate somatic symptoms in patients with depression and/ or anxiety disorders in psychiatry.