Validation of the Patient-Doctor-Relationship Questionnaire (PDRQ-9) in a representative cross-sectional German population survey.

The patient-doctor relationship (PDR) as perceived by the patient is an important concept in primary care and psychotherapy. The PDR Questionnaire (PDRQ-9) provides a brief measure of the therapeutic aspects of the PDR in primary care. We assessed the internal and external validity of the German version of the PDRQ-9 in a representative cross-sectional German population survey that included 2,275 persons aged ≥14 years who reported consulting with a primary care physician (PCP). The acceptance of the German version of this questionnaire was good. Confirmatory factor analysis demonstrated that the PRDQ-9 was unidimensional. The internal reliability (Cronbach's α) of the total score was .95. The corrected item-total correlations were ≥.94. The mean satisfaction index of persons with a probable depressive disorder was lower than that of persons without a probable depressive disorder, indicating good discriminative concurrent criterion validity. The correlation coefficient between satisfaction with PDR and satisfaction with pain therapy was r = .51 in 489 persons who reported chronic pain, indicating good convergent validity. Despite the limitation of low variance in the PDRQ-9 total scores, the results indicate that the German version of the PDRQ-9 is a brief questionnaire with good psychometric properties to assess German patients' perceived therapeutic alliance with PCPs in public health research.