Objective: The aim of this investigation was to examine the psychometric properties of the German 12-item General Health Questionnaire (GHQ-12) in a primary care sample.
Method: A sample (n = 421) of adult out-patients was screened using the GHQ-12. A standardized clinical interview (SCID) was conducted with all screened patients. Reliability, validity and factor analysis of the GHQ-12 were evaluated. Item characteristics were examined using item characteristics curves. Item bias analysis was performed using contingency tables.
Results: The German version of the GHQ-12 is a reliable instrument and performed well in detecting cases of psychological disorders. Factor analysis replicated the findings of earlier studies. Item characteristics curves and item bias analysis indicated that the individual items should be assessed carefully. One item was biased in relation to age, while another item showed a low positive response rate.
Conclusion: The GHQ-12 as a whole is a reliable questionnaire and can be a useful screening tool in primary care.