International Electronic Journal of Medicine (IEJM) Volume 2, Issue 1, Pages: 11-21 ISSN: 2251-8304 www.iejm.net Original Article Factor Structure of Persian General Health Questionnaire-28 in Dermatologic Patients: A Confirmatory Factor Analysis Amin Ghanbarnejad 1 , Habibollah Turki 2 , Banafsheh Golestan 3 , Mohammad Arbabi 4 , Saharnaz Nedjat 3 1. Research Center for Social Determinants for Health Promotion, School of Health, Hormozgan University of Medical Sciences (HUMS), Bandar Abbas, Iran 2. Research Center for Infectious and Tropical Disease, Hormozgan University of Medical Sciences (HUMS), Bandar Abbas, Iran 3. Dept. Of Epidemiology & Biostatistics, Tehran University of Medical Sciences (TUMS), Tehran, Iran. 4. Psychiatry and Psychology Research Center, Tehran University of Medical Sciences, Tehran, Iran Please cite this paper as: Ghanbarnejad A, Turki H, Golestan B, Arbabi M, Nedjat S. Factor structure of Persian General Health Questionnaire-28 in dermatologic patients: A Confirmatory Factor Analysis. Int Elec J Med. 2013;2(1):11-21. Corresponding author: Amin Ghanbarnejad, Instructor of Biostatistics, Research Center for Social Determinants for Health Promotion, School of Health, Hormozgan University of Medical Sciences (HUMS), Bandar Abbas, Iran. Tel: +98-761-3338583. E-mail: aghanbarnejad@hums.ac.ir Abstract Introduction: GHQ-28 is a screening instrument for evaluating psychiatric symptoms in vast groups of individuals. This study is the first attempt to examine the factor structure of the GHQ-28 in Iranian people. Methods: Three hundred and thirty six inpatients and outpatients who suffered from skin disease referred to Razi hospital in Tehran fully completed the GHQ-28 questionnaire. Factor structure of GHQ- 28 was assessed using confirmatory factor analysis. The comparison among four hypothesized models: orthogonal 4-factor, oblique 4-factor, Tau-equivalence oblique 4-factor and single second-order was done and the best model fitted to the data was obtained. The data was analyzed using SAS software. Results: Our findings showed that the oblique 4-factor and the single second-order models had the best fit based on fit indices; however the oblique 4-factor model was the best choice due to the smaller AIC and clearer interpretation. Conclusion: Assuming oblique factor model is a better realization of the practical situation using GHQ-28 among the dermatologic patients and show the stability and validity of the instrument in this population as a diagnostic tool. Key words: Dermatology, Questionnaires, Psychometric, Reproducibility of Results