The Self-Rating Depression Scale of Zung is an instrument for assessing depression simply and specifically, using traits found in the depressive disorders.
Questionnaire:
(1) 20 questions consisting of 10 symptomatically negative and 10 symptomatically positive questions
(2) increased duration associated with high score: questions 1, 3, 4, 7, 8, 9, 10, 13, 15, 19
(3) increased duration associated with low score: questions 2, 5, 6, 11, 12, 14, 16, 17, 18, 20
Points range from 1 (good) to 4 (poor)
self-rated raw score =
= SUM(points for all 20 questions)
average score =
= (self-rated raw score) / 20
SDS index =
= (self-rated raw score) / 80
Interpretation:
• minimum raw score 20
• maximum raw score 80
• minimum SDS index 0.25
• maximum SDS index 1.0
• index for normal, control population: 0.25-0.43
• index for people admitted with depression, but discharged with other diagnoses: 0.38-0.71
• index for people admitted and discharged with the diagnosis of depression: 0.63-0.90
