Reliability and validity of the Newcastle Scales in relation to ICD-9-classification

The assessment of endogenous depression by means of the Newcastle Scales (1965, 1971) has been validated by their correlation with biological findings in many previous studies. However, reliability and cross validation studies are lacking for these scales. We found the reliability of the Newcastle Scales to be sufficient or at least moderate in a sample of 70 inpatients with major depression. In order to cross validate both scales, the clinical classification according to ICD-9 and the assessment of the Newcastle Scales have been performed independently in a sample of 112 inpatients with Major Depressive Disorder (RDC). The rate of agreement between clinical diagnosis and classification according to the Newcastle Scales of endogenous depression is only fair. However, a modification of the diagnostic algorithm applied to the items of the Newcastle Scales I (1965) improves the rate of agreement considerably. The Newcastle Scale I turned out to represent a heterogenous concept without sufficient transferability. Modifications of both scales are proposed.