Measuring the depressive experience with a self-report measure: The Differentieller Depressions Fragebogen (DDF)

Background: This study aims to test the psychometric properties of the Italian version of a questionnaire developed to assess different aspects of depression: the Differentieller Depressions Fragebogen (DDF). The DDF is a self-report questionnaire consisting of 76 dichotomous (true/false) items distributed over six scales that consent a rapid and accurate assessment of depression. The dimensions of DDF are: 1) phobia; high scores on this scale refer to excessive fear coupled with avoidant behaviour; 2) somatization; high scores indicate the presence of physical symptoms that are not fully explained by a general medical condition; 3) hypochondriasis; subjects with high scores on this scale are characteristically preoccupied with their own bodies; 4) self-defeating; this scale takes into consideration rationalized conviction of guilt, fantasies of loss of approval, and delusion; 5) paranoia; high scores indicate hostility, problem with trust, envy, and shame; 6) obsessive-compulsive scale; patients with high scores on this scale are characterized by persistent intrusive thoughts (obsessions) and inflexible rituals (compulsions) that may be understood as efforts to reduce severe anxiety. Methods: The sample was composed of 437 subjects (34% male and 66% female) with a mean age of 35.75 years old (SD = 13.71). All participants completed the Italian version of the DDF. To verify some aspects of concurrent validity of the instrument, a part of the sample consisting of 73 patients, completed also the Italian version of the MMPI-2. Exploratory Factor Analysis (EFA) has been used to verify the factor structure of the instrument. Internal consistency has been verified using Cronbach's alpha coefficient. Results: Exploratory Factor Analysis (EFA) showed a structure with one principal factor (Depressive Experience). Second-Order Factor Analysis showed a structure with six factors and confirmed the original study The six scales showed a good internal consistency ranging from α = .70 (Phobia) to α = .82 (Self-Defeating) (Tab. III) Correlation between the DDF dimension and the MMPI-2 scales were statistically significant, in particular with the 1 (Hs) (Hypocondriasis) (r = .76** p < .01), 6 (Pa) (Paranoia) (r = .65**, p < .01), 7 (Pt) (Psychasthenia) (r = .61**, p < .01), 8 (Sc) (Schizophrenia) (r =.63**, p < .01), with the Harris and Lingoes (1955) subscales of depression - D3 (r = .65**, p < .01), D4 (r = .47**, p < .01), D5 (r = .48**, p < .01) (Tab. V), and with the MMPI-2 content scales, ANX (r = .58**, p < .01); OBS (r = .63**, p < .01); HEA (r = .85**, p < .01); BIZ (r = .75**, p < .01) (Tab. VI). Conclusions: Results obtained with Exploratory Factor Analysis (EFA) underline the presence of one factor and confirmed the original study. The DDF showed good psychometric properties. High correlation between the DDF dimensions and the MMPI-2 scales indicate the good concurrent validity of the instrument These findings suggest that the DDF may be useful in the asessment of Depression also in Italy.