Table 1

Well-known and validated subjective instruments to measure depression

Center for Epidemiologic Studies Depression Scale (CESD / CESD-R)29 30 Self-report questionnaire (20 items).
The CESD-R is a screening test for depression and depressive disorder. The CESD-R measures symptoms defined by the American Psychiatric Association's Diagnostic and Statistical Manual (DSM-V) for a major depressive episode.
Time frame: last 2 weeks.
Good psychometric properties: high internal consistency, strong factor loading. Validation with depression in the general population.31
Composite International Diagnostic Interview (CIDI)32 Structured interview administered by trained (but lay) interviewer.
CIDI is a comprehensive, fully-structured interview for the assessment of mental disorders according to the ICD-10 and DSM-IV, intended for use in epidemiological studies, for clinical or research purposes.
Time frame: last 4 weeks.
Good validation and concordance with standardised clinical assessments conducted by a clinician to diagnose mental disorders. Areas under curve for the 12-month prevalence of anxiety disorder and any mood disorder were 0.88 and 0.83 respectively. The CIDI has a good concordance with blinded clinical diagnoses.33–35
Beck Depression Inventory (BDI / BDI-II)36 37 Self-report questionnaire (21 items) to assess depressive symptoms and symptom severity.
BDI was originally based on clinical observations and patient descriptions.
BDI-II was developed to correspond with DSM-IV criteria for depression.
Two subscales: affective and somatic symptoms.
Time frame: past week (BDI) / last 2 weeks (BDI-II).
High internal consistency: alpha coefficients around 0.86 for psychiatric and 0.81 for non-psychiatric populations. Good sensitivity and specificity for depression in comparison with gold standards. High reliability, concurrent, content and structural validity.38
Patient Health Questionnaire-9 (PHQ-9)39 Self-report questionnaire (9 items).
Instrument for screening, diagnosing, monitoring and measuring the severity of depression.
Time frame: last 2 weeks.
Criterion validity was assessed against an independent structured mental health professional interview. The sensitivity was 88% and the specificity was 88% for major depression. Good construct validity to recognise major depression, but also depressive disorder in the general population40–42