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Q Does the sentence completion test for depression differentiate between people with and people without depression?
METHODS
Design:
Diagnostic cohort study.
Setting:
One clinical psychology service, UK; time period not stated.
Patients:
Cohort 1: 25 adult outpatients with major depressive disorder (MDD; clinical diagnosis and mean Beck Depression Inventory (BDI) score 33, range 26–51) and 25 people without MDD (no symptoms reported to GP in previous month, not receiving pharmacological or psychological therapy for depression or anxiety; mean BDI score 4, range 0–8). People with learning disabilities, substance abuse problems, bipolar disorder, psychotic symptoms, or dementia were excluded. Cohort 2: 20 adult outpatients with major depressive disorder and 20 people without MDD (inclusion and exclusions as for cohort 1).
Test:
Cohort 1: The full length sentence completion test for depression (SCD), consisting of 48 short sentence stems, for example: “The world …”, “I think …” which the participant completed to reflect their feelings during the last week. Completed statements are coded as being negative or positive or neutral. Cohort 2: Short form SCD, 15 sentence stems selected from the full length version on the basis of high discriminative performance in cohort 1.
Diagnostic standard:
Structured clinical assessment and BDI (score ⩾25 needed for diagnosis of depression, ⩽13 for not depressed).
Outcomes:
Sensitivity and specificity.
MAIN RESULTS
For the full length sentence completion test for depression (SCD), using a cut off score of 16 negative completions for a diagnosis of depression gave a sensitivity of 92% and a specificity of 96%. The short form SCD had a sensitivity and specificity of 100% when used with a cut off score of 5 or more negative completions.
CONCLUSIONS
The full length and short forms of the SCD show high sensitivity and specificity for the differentiation between people with and without clinically diagnosed major depressive disorder.
NOTES
One limitation of the study may be the use of clinical assessment rather than a research diagnostic interview. In addition, estimates of sensitivity and specificity may not be representative of what might be achieved in the general population, due to the use of two well defined comparator groups, with non-contiguous ranges of BDI scores.
Commentary
A multiplicity of validated self report depression questionnaires is available both for research and medical care. The study by Barton et al is innovative because it investigates the reliability and validity of a completely different type of self report questionnaire, the sentence completion test for depression (SCD). Whereas conventional self report questionnaires assess the presence of various depression symptoms using preset response categories,1 the SCD includes 48 brief sentence stems (short form: 15 sentence stems), and the patient is asked to provide continuations to the incomplete sentences. The total score of the SCD is assessed by adding the number of negative and positive completions.
Based on the results of three studies, the authors report good internal consistency, interrater reliability, construct validity, criterion validity, and sensitivity to change for the SCD. However some methodological limitations deserve mentioning: the sample sizes for all three studies were small (n = 50, n = 40, and n = 18, respectively), only patients with either very high or very low depression scores were included (BDI ⩾25, or BDI ⩽13, respectively), and no validated diagnostic interview was used as the criterion standard for depressive disorder.
The clinical value of the SCD is that it gives specific information on the patients’ attitudes towards themselves, their interpersonal relationships, the world, the future, and the past. This information is particularly useful for the mental health professional treating someone with depression. Given the preliminary psychometric properties of the SCD, the low level of standardisation, and the relatively high expenditure of time for both patient and mental health professional, the SCD will not supersede conventional self report depression questionnaires. For case finding, measuring depression severity, establishing depression diagnosis, and monitoring response to treatment, brief conventional questionnaires with preset response categories2,3 seem more practical and efficient. Altogether, the SCD appears as an ideographic depression measure that is clinically promising when used complementary to conventional self report depression questionnaires.
Footnotes
For correspondence: Dr Stephen Barton, School of Neuroscience and Psychiatry, University of Newcastle, Ridley Building, Newcastle Upon Tyne NE1 7RU, UK; s.b.bartonncl.ac.uk
Sources of funding: none reported.