The Interval General Health Questionnaire and its relationship with psychiatric disorder in community and general practice samples.

This paper contrasts the usual scoring of the GHQ-30 with scoring based upon a criterion approach applied to only 12 of the GHQ items that takes account of the 'diagnostic significance' of the chosen items. Repeat assessments with this shorter form of the questionnaire (the I-GHQ), coupled with procedures to assess change, can be used to provide summary measures of symptom course in those research situations where available interview time precludes the use of more formal assessment methods.