Validation of the Hungarian PHQ-15. A latent variable approach.

Background and purpose Somatic symptoms without a clear-cut organic or biomedical background, also called "medically unexplained" or "somatoform" symptoms, are frequent in primary and secondary health care. They are often accompanied by depression and/or anxiety, and cause functional impairment. The Patient Health Question-naire Somatic Symptom Scale (PHQ-15) was developed to measure somatic symptom distress based on the frequency and bothersomeness of non-specific somatic symptoms. The study aimed to (1) evaluate the Hungarian version of the PHQ-15 from a psychometric point of view; (2) replicate the bifactor structure and associations with negative affect described in the literature; and (3) provide the Hungarian clinical and scientific community with reference (normal) values split by sex and age groups. Methods PHQ-15, depression (BDI-R), and subjective well-being (WHO-5) scores obtained from a large (n = 5020) and close to representative community sample (Hun-garostudy 2006) were subjected to correlation analysis and linear structural equation modeling. Results The PHQ-15 showed good internal consistency (Cronbach's α = 0.810; McDonald's ω = 0.819) and moderate to strong correlation with the BDI-R (rs = .49, p < 0.001) and WHO-5 (rs = -.48, p < 0.001). Fit of the bifactor structure was excellent; in independent analyses, the general factor was strongly associated with depression (β = 0.656±0.017, p < 0.001) and well-being (β = -0.575±0.015, p < 0.001), whereas the symptom specific factors were only weakly or not related to these constructs. The PHQ-15 score was higher in females and showed a weak positive association with age. The Hungarian PHQ-15 is a psychometrically sound scale which is positively associated with depression and ne-gatively related to subjective well-being. The bifactor structure indicates the existence and meaningfulness of a gene-ral factor representing the affective-motivational component of somatic symptom distress. Conclusion The Hungarian version of the PHQ-15 is a brief and usable tool for the pre-screening of somatization disorder (DSM-IV) or somatic symptom disorder (DSM-5). The reported reference values can be used in the future for both clinical and research purposes.