Purpose: Depressed and exhausted mood warrants epidemiological scrutiny as a cardiovascular risk factor. We evaluated the reliability and validity of a symptom-driven diagnostic scale.
Methods: To assess a depressed mood, items were derived from an extended battery of psychosocial questionnaires in a population-based study including 11,949 subjects aged 25 to 74 years.
Results: Eight items from the 24-item von Zerssen checklist were extracted by factor analysis resulting in an approximately normally distributed scale (range 0-24; mean=8.23, SD 4.76). Median for men was 8.00 and 10.00 for women. Its internal consistency was high (Cronbach's alpha 0.88). Test-retest reliability of a sub-sample was 0.83. Determining concurrent validity, correlation coefficients against a single depression questionnaire in 8237 subjects (p < 0.001) and SF-36 subscales (vitality and mental health) (both p < 0.0001) in 4226 subjects proved to be significant. Construct validity was confirmed by significant associations (all p < 0.001) with sleeping complaints, social isolation, and unhappiness. Test values for men above the 80th percentile exhibited significant hazard ratios for subsequent total mortality (80th percentile: HR 2.17, 95% CI: 1.31-13.55).
Conclusion: The scale comprises eight items describing motivational depletion, decreased vitality, irritability, and an anxious mood with sufficient internal and external reliability, concurrent and construct validity. Its normal distribution allows a graduated analysis of different thresholds. The instrument may be particularly useful to identify exhausted and depressed mood of otherwise apparently healthy subjects in the general population.