Format validation of the PHQ-15 questionnaire version for the Mexican population to assess psychosomatic symptoms

Psychosomatic symptoms are physical manifestations of psychological origin that are not adequately explained by organic causes. For this reason, it is difficult to differentiate them from other conditions, so health sciences must consider their diagnosis and research on them a priority. The PHQ-15 (Patient Health Questionnaire) is an instrument that allows its diagnosis through a list of 15 psychosomatic symptoms. The purpose of this research was to validate the PHQ-15 for the Mexican adult population, obtaining indicators of reliability, construct, and convergent validity. First, the instrument was translated and culturally adapted. This version was evaluated by mental health specialists and doctors. The PHQ-15 and the Hospital Anxiety and Depression Scale (HADS) were applied to 420 Mexican participants through an online survey. A Confirmatory Factor Analysis was performed that rectified the unifactorial structure. The results showed acceptable fit indicators and a significant contribution of all the reagents to the model. The correlations between the PHQ-15 and the HADS showed a directly proportional relationship between psychosomatic symptoms with depression and anxiety, which provides evidence of convergent validity. Regarding internal consistency, it showed adequate levels of reliability.