The Patient Health Questionnaire-9: the Czech version

Research objectives. Depression is a very common mental disorder. The Patient Health Questionnaire-9 (PHQ-9) has been frequently used to assess depression in primary healthcare, as well as in research studies. The aim of this study was to assess the Czech version of the PHQ method. Sample and setting. The final study population included 1654 respondents (66,6% of women and 33,4% of men) addressed via social networks within a broader study on motivations for sex. Statistical analysis. The authors calculated the Confirmatory Factor Analysis to assess which of the previously hypothesized factor structures (one- or two-factor solutions) would best fit the data. The authors calculated the Multi Sample Analysis to assess measurement invariance across two translations of the method into Czech. First version was translated by the authors. The second version, which is available online is the Pfizer company translation. The authors further tested the data for gender invariance. Results. The two-factors model suggests the best fit with five 'somatic' items and four 'non-somatic' or 'affective' items. The model was partially invariant across the two translations. Two items were responsible for non-invariance. The model for version DOMOV was invariant across gender. The model for version Pfizer was partially invariant across gender. One item was responsible for non-invariance. Recommendations are suggested in the discussion. The item analysis indicates that the items are suitable for the scale and the internal consistency of the scale is satisfactory. The correlation between PHQ-9 and BDI-II is consistent with previous findings of a meta-analytic study. The Czech version of PHQ-9 is a useful tool for assessing depression in the general population. Study limitations. Future research should focus on clinical populations.