Background: About one in five patients with depression experiences a chronic course. Despite the great burden associated with this disease, there is no current screening instrument for Persistent Depressive Disorder (PDD). In the present study, we examine a short screening test, the persistent depression screener (PDS), that we developed for DSM-5 PDD. The PDS is comprised of one question that is administered following an initial self-assessment for depression.
Methods: Ninety patients from an inpatient clinic/day clinic specialized in treating depression completed the PDS. They were also assessed using a structured clinical interview covering the DSM-5 criteria for PDD. Retest reliability was examined after two weeks (n = 69, 77%).
Results: In this sample, the prevalence of PDD was 64%. Sensitivity of the PDS was 85% with a positive predictive value of 80%. Specificity was 63%. Positive and negative likelihood ratios were 2.3 and .24, respectively. Agreement between the PDS results and the outcome of the clinical interview was moderate (Cohen's Kappa κ = .48 ([95%-CI .28, .68], p < .001, SE = 0.10)). Prevalence-adjusted bias-adjusted Kappa was PABAK = .53. Retest reliability of the PDS was moderate (Cohen's Kappa κ = .52 ([95%-CI .3, .74], p < .001, SE = 0.11)).
Conclusions: The present study shows that the PDS - when applied following a self-rating depression scale - might be a valid and reliable way to detect PDD. However, the results of the PDS must be confirmed by a diagnostic interview.
Keywords: Depressive disorders; Diagnostic interview; Dysthymia; Persistent depressive disorder; Rater agreement; Screening question.