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Practical Information
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Instrument Name:
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Schwab-Gilleard Depression Scale (SGDS)
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Instrument Description:
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The scale measures depression in the elderly. The SGDS consists of 10 items drawn from a structured interview to assess multiple psychopathologies developed by Schwab, Holzer and Warheit in 1973. (Ref: 1)
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Price:
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Free (article appendix; Ref: 2)
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Administration Time:
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No information found; we estimate 10 minutes
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Publication Year:
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1981
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Item Readability:
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Flesch-Kincaid grade level of 3.6; a person with at least a third grade education should be able to read and comprehend the scale.
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Scale Format:
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4-point Likert scale ranging from ‘most of the time’ (3) to ‘never’ (0).
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Administration Technique:
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No training is required to administer; may be used as a self-administered questionnaire or read aloud to the patient. Both administration methods have been used. (Refs: 2,4)
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Scoring and Interpretation:
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Sum all items; total score range is 0 to 3. A cut-score of 14 yields sensitivity=84% and specificity=90% compared to a DSM-III-R depression diagnosis. (Ref: 3)
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Forms:
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No other forms found.
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Research Contacts
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Instrument Developers:
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C. Gilleard, M. Wilmott and K. Vaddadi
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Instrument Development Location:
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University Department of Psychiatry, Royal Edinburgh Hospital, Edinburgh.
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Instrument Developer Email:
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No information found.
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Instrument Developer Website:
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No information found.
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Annotated Bibliography
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1. Schwab JJ, Holzer CE, Warheit GJ. Depressive symptomatology and age. Psychosomatics. 1973 14:135-141.
[PMID:4794902]
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Purpose: To present an analysis of the frequency of depression symptoms, according to age. To review responses to interview items in order to contribute to the sociology of depression. |
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Sample: A random sample 1,645 respondents completed the Interview Schedule. 44.7% male, 55.3% female; 77.6% white, 22.4% black; mean age=41 years; 15.9% had annual income less than $3,000 per year, 18% had annual income greater than $15,000 per year; 60.9% married, 17.9% single, 10.3% widowed, 6.2% divorced, 4.2% separated. |
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Methods: Respondents were administered an Interview Schedule that contained 317 items, 18 of which were questions that measured a multidimensional concept of depression, based on the work of others (Freud, Abraham, Rado, Fenichel, Bibring). The interviews were administered to the respondents in their homes and took two hours to complete. |
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Implications: A large percentage of the youngest and oldest cohorts showed numerous and varied depressive symptoms. The authors question whether the youngest and oldest cohorts are “societal rejects." |
2. Gilleard CJ, Willmott M, Vaddadi KS. Self-report measures of mood and morale in elderly depressives. Br J Psychiatry 1981 Mar;138:230-5. [PMID: 7272615]
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Purpose: To examine the effectiveness of two scales (SGDS and Bigot’s Life Satisfaction Index) in identifying clinical depression in the elderly. |
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Sample: 45 elderly psychiatric inpatients with depression diagnoses and 45 non-patient community-residing controls. |
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Methods: The questionnaires were administered to the subjects, matched on age and sex. 18 inpatients were involved in test-retest at discharge. Observed overt depression behaviors (weeping and expressing a wish to die) were recorded for all patients – 11 of the patients demonstrated these behaviors. |
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Implications: At test-retest (6 to 8 weeks after the beginning of depression treatment, upon discharge from the hospital), depression had declined and life satisfaction had increased. There was a significant relationship between overt depressive behavior and increased self-report of depression and decreased report of life satisfaction. |
3. Hickie C, Snowdon J. Depression scales for the elderly: GDS, Gilleard and Zung. Clin Geron 1987 6(3):51-53. [No PMID]
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Purpose: To validate the GDS and the SGDS in an Australian sample and determine appropriate cut-scores.
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Sample: Thirty-nine subjects (26 female, 13 male) of a day center, a general psychiatry ward, nursing homes and psychiatry outpatients. Inclusion criteria included age over 65 years, English speaking and reading, no current or past history of non-affective psychosis, no current manic episode, and no evidence of delirium or dementia. Mean age=75 years, 20 had major depression, 19 were not depressed.
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Methods: Absence or presence of major depression was determined by DSM-III interview criteria. The GDS and SGDS were administered, as well as the Zung for comparison purposes.
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Implications: The SGDS was shorter than the Zung, without sacrificing accuracy. All three scales satisfactorily distinguished depressed and nondepressed groups.
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4. Richardson CA, Hammond SM. A psychometric analysis of a short device for assessing depression in elderly people.Br J Clin Psychol. 1996 Nov;35 ( Pt 4):543-51.
[PMID:8955540]
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Purpose: To examine the psychometric properties of the SGDS, specifically its ability to differentiate between depression and dementia. |
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Sample: 166 elderly persons from Southwest London, residing in Part III residential homes (local authority inhouse/social service provided). 98% over age 65: 57% were 85 years or older, 37% were aged 75-84. Also, a subsample of 49 persons were assessed on the SGDS and CARE 14 months prior, was used for the test-retest.
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Methods: Measures included the SGDS, another depression self-report scale (Geriatric Depression Scale; GDS), cognitive and behavioral disability scales (Cognitive Assessment Scale and Behavior Rating Scale) of the Clifton Assessment Procedures for the Elderly) and observer-rated measures of depression and dementia (Comprehensive Assessment and Referral Evaluation; CARE). 111 subjects completed all scales, 55 received only the GDS and CAPE. Psychiatric notes were available for each subject. |
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Implications: See applicable sections of this review. |
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Factors and Norms
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Factor Analysis Work:
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No information found.
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Normative Information Availability:
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No information found.
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Reliability Evidence
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Test-retest:
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SGDS scores taken 14-months apart correlated 0.71 (raw correlation) and 0.82 (disattenuated). Disattentuation is used to estimate the correlation between two measures if there was no unreliability. The basic formula is the raw correlation between X and Y divided by the square root of the product of the reliabilities of the measures. It is of most use to determine if validity coefficients indicate that measures are assessing the same construct after eliminating measurement error. The fact that the disattenuated correlation is only 0.82 (we would expect closer to one if we were measuring the same thing) would suggest that the characteristic being measured has changed in the subjects. Given the high alphas, we do not think it’s caused by unreliability. (Ref: 4)
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Inter-rater:
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No information found.
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Internal Consistency:
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Cronbach’s alpha was 0.86 (compared to GDS alpha=0.92 and CARE depression alpha = 0.91). Spearman Brown was then computed to correct for differences in scale length: SGDS r=0.38 (compared to GDS r=0.28 and CARE depression = 0.36). (Ref: 4)
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Alternate Forms:
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No information found.
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Validity Evidence
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Construct/ Convergent/ Discriminant:
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In support of construct validity, in a study of depressed inpatients and normal controls, the depressed patients reported higher SGDS scores (t=7.2, p<0.001). (Ref: 2) Similarly, compared to the normal controls and inpatients without overt depressive behaviors, inpatients with overt depressive behavior reported higher SGDS scores (‘overt’ mean=20.5, SD=5.8; ‘others’ mean=13.1, SD=5.8; t=3.3, df 28, p<0.01). (Ref: 2)
In support of disciminant validity, the SGDS correlated at only 0.17 with the CARE dementia scale, -0.19 with the Cognitive Assessment Scale, and and 0.10 with the Behavior Rating Scale measures of dementia). Further, SGDS scores did not differ between demented (n=26) and non-demented (n=98) subsamples, suggesting the SGDS is not confounded by dementia. (Ref: 4)
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Criterion-related/ Concurrent/ Predictive:
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The SGDS shows high correlations with other self-rated depression scales: GDS r= 0.79 (Ref: 4), GDS r = 0.89 (Ref:3), CARE depression scale r=0.68 (Ref: 4), Zung Self-Rating Depression Scale r=0.88 (Ref:3).
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Content:
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No information found.
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Responsiveness Evidence:
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18 depressed individuals were tested at admission to and discharge from an inpatient psychiatric unit. SGDS scores were significantly reduced (z=2.53, p<0.01). (Ref: 2)
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Scale Application in VA Populations:
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No information found.
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Scale Application in non-VA Populations:
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Yes. (Ref: 2-4)
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Comments
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The SGDS possesses adequate internal consistency reliability and promising preliminary evidence of validity. It is useful that validity evidence has been collected both on a clinical sample and a more widely representative sample from a residential home. It should be noted that the SGDS has not been documented for use with depressed community-dwelling individuals. The test-retest data is not compelling given the long time interval (14 months). It is not at all clear that one should would expect depressive symptoms to be stable for such a long time period. In sum, this appears to be an adequate instrument, however there are several other short depression scales designed for use with the elderly for which larger bodies of research exist. It appears that the SGDS is measuring something different than the care depression scale based on the fact that the GDS is more highly correlated to the care depression measure than the SGDS. Some factor analytic work probably needs to be done to characterize the aspects of depression involved in these different measures.
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Updates
No information found.
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