The validity of the General Health Questionnaire for first-stage screening for mental illness in pain clinic patients.

The validity of the 28-item version of the General Health Questionnaire (GHQ-28) was determined by comparison with the Clinical Interview Schedule (CIS) in 56 pain clinic patients. Despite some limitations, the GHQ can be used effectively and cheaply as the first stage of an assessment to identify potential "cases" of mental disorder which must then be verified using a second-stage clinical interview such as the CIS. This process can result in a considerable reduction in the proportion of patients requiring a psychiatric interview and, therefore, in reduced service costs. Factors associated with lower validity coefficients include female sex, age above 60 years and pain with a duration of less than 2 years.