A clinical index for rating severity in Cushing's syndrome

In assessing the clinical response to medical and/or surgical treatments in patients with established Cushing's syndrome, the need for an instrument that could measure the magnitude of changes in the most common symptoms was felt. We therefore tested the usefulness of a simple clinical index, the Cushing's syndrome severity index (CSI), based on clinimetric principles. Eight clinical features were selected. Each one was graded on an ordinal 3-point scale (0-2) with specification of anchor points based on severity. The total score ranged from 0 to 16.

Interrater agreement, construct validity and concurrent validity of the index were evaluated. Fourteen patients with Cushing's syndrome were evaluated independently by 2 endocrinologists before and after successful treatment. The CSI and two global scales of illness severity were administered. Urinary cortisol measurements were also performed.

The intraclass correlation coefficient of the CSI was 0.95 before treatment and 0.87 after treatment. The CSI significantly discriminated (p<0.001) the effects of treatment and paralleled the changes in urinary cortisol. There were significant correlations between CSI and global scales of illness severity and change after treatment.

The results indicate that the CSI is a valid and reliable clinimetric method to evaluate severity in Cushing's syndrome. It may provide a tool for better assessing the complex array of signs and symptoms in this condition. The index is suitable for descriptive studies, outcome investigations and treatment trials.