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

Toyabe, Shin-ichi; Shioiri, Toshiki; Kobayashi, Kuriko; Kuwabara, Hideki; Koizumi, Masataka; Endo, Taro; Ito, Miki; Honma, Hiroko; Fukushima, Noboru; Someya, Toshiyuki; Akazawa, Kouhei

The twelve-item version of the General Health Questionnaire (GHQ-12) is used as a screening instrument for psychological distress in the general population [1, 2] . GHQ-12 has been widely used as a unitary measure [3, 4] , but two or more underlying factors have been identified in previous studies based on factor analyses [5] [6] [7] . Scoring methods, clinical groups, different cultures and sampling time affected the number of factors that have been identified and the item loadings for each factor [5] . There have been many publications related to the psychological distress on survivors in a large disaster. They include devastating earthquake [8] [9] [10] , air disaster [11] , Chernobyl disaster [12] , Severe Acute Respiratory Syndrome (SARS) epidemic [13] and war [14, 15] . We previously reported psychological distress of subjects who had experienced the Niigata-Chuetsu Earthquake determined by using GHQ-12 at five months after the earthquake [16] . The earthquake (6.8 on the Richter scale) occurred at 5:56 P.M. on October 23, 2004 in the Niigata-Chuetsu region of Japan, and numerous aftershocks occurred until 28 December. More than 4,500 people were injured and 120,000 houses were completely or partially destroyed by the earthquake. Even at five months after the earthquake, 9,600 people who had lost their houses were living in temporary housing. At that time, recovery from the psychological distress caused by the earthquake was significantly impaired. A two-factor model using chronic scoring method [17] was found to show the highest level of goodness-of-fit, and the factor 'social dysfunction' was more severely affected than the factor 'dysphoria'. The impairment in the factor 'social dysfunction' was the most remarkable in the elderly and seemed to be a cause for the impaired psychological recovery in the elderly.