Does the 12-item General Health Questionnaire contain multiple factors and do we need them?

Fei Gao¹ , Nan Luo² , Julian Thumboo³ , Calvin Fones⁴ , Shu-Chuen Li⁵ and Yin-Bun Cheung⁶

¹Clinical Trials and Epidemiological Sciences, National Cancer Centre, 11 Hospital Drive, 169610, Singapore

²Institute of Health Economics, #1200, 10450 Jasper Avenue, Edmonton, Alberta, T5J 3N4, Canada

³Department of Rheumatology and Immunology, Singapore General Hospital, Outram Road, 169608, Singapore

⁴Department of Psychological Medicine, National University of Singapore, 5 Lower Kent Ridge Road, 119074, Singapore

⁵Department of Pharmacy, National University of Singapore, 18 Science Drive 4, 117543, Singapore

⁶MRC Tropical Epidemiology Group, IDEU, ITD, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK

author email corresponding author email

Health and Quality of Life Outcomes 2004, 2:63doi:10.1186/1477-7525-2-63


Published:	11 November 2004

Abstract

Background

The 12-item General Health Questionnaire (GHQ-12) is widely used as a unidimensional instrument, but factor analyses tended to suggest that it contains two or three factors. Not much is known about the usefulness of the GHQ-12 factors, if they exist, in revealing between-patient differences in clinical states and health-related quality of life.

Methods

We addressed this issue in a cross-sectional survey of out-patients with psychological disorders in Singapore. The participants (n = 120) completed the GHQ-12, the Beck Anxiety Inventory, and the Short-Form 36 Health Survey. Confirmatory factor analysis was used to compare six previously proposed factor structures for the GHQ-12. Factor scores of the best-fitting model, as well as the overall GHQ-12 score, were assessed in relation to clinical and health-related quality of life variables.

Results

The 3-factor model proposed by Graetz fitted the data better than a unidimensional model, two 2-factor models, and two other 3-factor models. However, the three factors were strongly correlated. Their values varied in a similar fashion in relation to clinical and health-related quality of life variables.

Conclusions

The 12-item General Health Questionnaire contains three factors, namely Anxiety and Depression, Social Dysfunction, and Loss of Confidence. Nevertheless, using them separately does not offer many practical advantages in differentiating clinical groups or identifying association with clinical or health-related quality of life variables.