Zung Self-Rating Depression Scale
Evaluates depression symptoms to determine the severity of the depressive disorder the patient suffers from.
In the text below the calculator you can find more information on how the scale should be interpreted and a list of the main depression symptoms.
The Zung self-rating depression scale represents a self-administered questionnaire aimed at revealing the severity of the depressive disorder based on the frequency of the main depression signs and symptoms.
The Zung SDS has been validated in numerous studies and is recommended for monitoring purposes.
The numerical result obtained by summing the points from each item of the Zung SDS is interpreted as follows:
Raw score (20 – 80) | SDS Index (25 – 100) | Interpretation |
20 – 39 | 25 – 49 | Normal range |
40 – 47 | 50 – 59 | Mild Depression |
48 – 55 | 60 – 69 | Moderate or marked depression |
56 – 80 | 70 – 100 | Severe depression |
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Zung depression scale explained
The Zung SDS is addressed to adult patients who suffer from depression symptoms. These are assessed on two sets of Likert scales. The scale was first published by Zung in 1965.
Some of the items in this self-report questionnaire are formulated in a positive manner whilst others are formulated in a negative manner, meaning that although the items in the Likert scale remain the same, their order and associated points change.
Items 1, 3, 4, 7, 8, 9, 10, 13, 15, 19 are scored:
■ A little of the time (1);
■ Some of the time (2);
■ Good part of the time (3);
■ Most of the time (4).
For items 2, 5, 6, 11, 12, 14, 16, 17, 18, 20 the scale is reversed as follows:
■ Most of the time (1);
■ Good part of the time (2);
■ Some of the time (3);
■ A little of the time (4).
The following table introduces the symptoms covered in the Zung SDS, which reflect four areas: pervasive effect, physiological equivalents, psychomotor activities and other disturbances:
Depressed mood; Anhedonia; Clouded reasoning; Difficulty with completing tasks; Difficult decision making; Morning symptoms; |
Insomnia; Restlessness; Lack of hope; Irritability; Diminished self esteem; Suicidal ideation; |
Fatigue; Palpitations; Diminished appetite; Weight loss; Constipation; Sexual interest; |
The Zung depression scale is recommended for clinical monitoring purposes and has been validated through several studies. For diagnosis of depression, other investigation methods should be employed.
Score interpretation
In this self-report questionnaire, each of the 20 items is awarded a number of points from 1 to 4, depending on the experienced frequency of the depression symptoms.
The overall score ranges from 20 to 80. In some clinical settings, this is reported as a SDS index, with values between 25 and 100.
The conversion to the SDS Index (the 100 point scale) follows the below equation:
SDS Index = Raw score x 1.25
The table below summarizes the score categories:
Raw score (20 – 80) | SDS Index (25 – 100) | Interpretation |
20 – 39 | 25 – 49 | Normal range |
40 – 47 | 50 – 59 | Mild Depression |
48 – 55 | 60 – 69 | Moderate or marked depression |
56 – 80 | 70 – 100 | Severe depression |
Regardless of the reporting system, the higher the score, the more severe the depression symptoms.
Main depression symptoms
Depressive disorder is characterized by a variety of symptoms and not all cases display similar signs. Also, some case may display combinations of symptoms with other mental conditions, such as bipolar, anxiety or attention deficit disorders.
The main depression symptoms include:
■ Persistent sadness;
■ Feelings of hopelessness or guilt;
■ Irritability;
■ Excessive worrying;
■ Anxiousness;
■ Suicidal ideation;
■ Psychosomatic pain;
■ Eating or sexual behaviour disorders;
■ Insomnia;
■ Disruption of biological patterns.
Original source
Zung WW. A Self-Rating Depression Scale. Arch Gen Psychiatry. 1965; 12:63-70.
Validation
Zung WW, Richards CB, Short MJ. Self-rating depression scale in an outpatient clinic. Further validation of the SDS. Arch Gen Psychiatry. 1965; 13(6):508-15.
Other references
1. Biggs JT, Wylie LT, Ziegler VE. Validity of the Zung Self-rating Depression Scale. Br J Psychiatry. 1978; 132:381-5.
2. Carroll BJ, Fielding JM, Blashki TG. Depression rating scales. A critical review. Arch Gen Psychiatry. 1973; 28(3):361-6.
Specialty: Psychiatry
System: Nervous
Objective: Assessment
Type: Scale
No. Of Items: 20
Year Of Study: 1965
Article By: Denise Nedea
Published On: August 28, 2017 · 02:22 AM
Last Checked: August 28, 2017
Next Review: August 28, 2023