Research article

Factor structure of the General Health Questionnaire (GHQ-12) in subjects who had suffered from the 2004 Niigata-Chuetsu Earthquake in Japan: a community-based study

Shin-ichi Toyabe¹ , Toshiki Shioiri^2,3 , Kuriko Kobayashi¹ , Hideki Kuwabara² , Masataka Koizumi² , Taro Endo² , Miki Ito^2,3 , Hiroko Honma⁴ , Noboru Fukushima⁵ , Toshiyuki Someya² and Kouhei Akazawa¹

¹Department of Medical Informatics, Niigata University Medical and Dental Hospital, Asahimachi-Dori 1, Niigata 951-8520, Japan

²Department of Psychiatry, Niigata University Graduate School of Medical and Dental Sciences, Asahimachi-Dori 1, Niigata 951-8510, Japan

³Group of Mental Health, Section of Safety Net of Life, Research Center for Natural Hazards and Disaster Recovery, Niigata University, Igarashi-2-8050, Niigata 950-2181, Japan

⁴Niigata Institute for Traumatic Stress, Kawagishicho 1-57-1, Niigata 951, Japan

⁵Niigata Prefectural Mental Health and Welfare Center, Kamitokoro-2-2-3, Niigata 950-0994, Japan

author email corresponding author email

BMC Public Health 2007, 7:175doi:10.1186/1471-2458-7-175

Published:	24 July 2007

Abstract

Background

Factor structure of the 12-item General Health Questionnaire (GHQ-12) was studied by a survey of subjects who had experienced the 2004 Niigata-Chuetsu earthquake (6.8 on the Richter scale) in Japan.

Methods

Psychological distress was measured at two years after the earthquake by using GHQ-12 in 2,107 subjects (99.0% response rate) who suffered the earthquake. GHQ-12 was scored by binary, chronic and Likert scoring method. Confirmatory factor analysis was used to reveal the factor structure of GHQ-12. Categorical regression analysis was performed to evaluate the relationships between various background factors and GHQ-12 scores.

Results

Confirmatory factor analysis revealed that the model consisting of the two factors and using chronic method gave the best goodness-of-fit among the various models for factor structure. Recovery in the scale for the factor 'social dysfunction' was remarkably impaired compared with that of the factor 'dysphoria'. Categorical regression analysis revealed that various factors, including advanced age, were associated with psychological distress. Advanced age affected the impaired recovery of factor 'social dysfunction' score as well as total GHQ score.

Conclusion

The two-factor structure of GHQ-12 was conserved between the survey at five month and that at two years after the earthquake. Impaired recovery in the ability to cope with daily problems in the subjects who had experienced the earthquake was remarkable even at two years after the earthquake.