About the Scale

Calgary Depression Scale for Schizophrenia

Type: Psychiatric Status Rating Scale See MeSH https://www.ncbi.nlm.nih.gov/mesh/?term=psychiatric+status+rating+scales

Subject: Assessment of depressive symptoms separate from positive, negative and extrapyramidal symptoms in people with schizophrenia.

Administration: Observer rated scale structured, goal directed interview.

Time Axis: Two weeks unless otherwise specified.

Item Selection: Factor analysis from Present State Examination and Hamilton Depression Rating Scale.

Number of Items: Nine

Scoring: The CDSS depression score is obtained by adding each of the item scores. To select a cut-off point refer to the attached PDF. A score above 6 has an 82% specificity and 85% sensitivity for predicting the presence of a major depressive episode.  CDSS SCORING

Definition of Items: All ratings of the items are defined according to operational criteria from 0-3.

Psychometric Properties:  Construct validity: has been confirmed by correlations with other depression rating scales and by the prediction of a major depressive episode.

Divergent validity: from positive, negative and extrapyramidal symptoms has been established by the absence of correlations with measures of these symptoms.

Predictive validity: The level of depression assessed by CDSS and the level of negative symptoms differentially predict outcome.

Reliability: Internal reliability of the scale has been shown to be good, as has inter-rater reliability.

Ages: The Calgary Depression Scale has been validated in adolescents and adults.

Sensitivity to Change: The scale has been shown to be sensitive to change in numerous randomized controlled studies in which it has been an outcome measure.

Minimum Clinically Important Difference: 1.5, based on the SEM approach Amri I, Millier A, Toumi M. Value Health. 2014 Nov; 17(7):A766. doi: 10.1016/j.jval.2014.08.288. Epub 2014 Oct 26.

Training: The rater should have experience with people with schizophrenia and should develop inter-rater reliability with another rater experienced in the use of structure assessment instruments. An experienced rater should develop adequate inter-rater reliability within 5 practice interviews.