Clinical characteristics of patients with diagnostic uncertainty of major depressive disorder

•Daily psychiatric practice shows how physicians must deal with uncertainty.•Even the DSM-5 does not provide highly reliable diagnosis of depression.•Physicians were unable to confidently diagnose depression in 40% of the cases.•Comorbidity of anxiety disorders were associated with the diagnostic uncertainty. Physicians do not always confidently diagnose psychiatric disorders. The present study was conducted to identify the clinical characteristics of patients in whom a definitive diagnosis of major depressive disorder (MDD) could not be established. The participants were 199 consecutive outpatients with MDD, who were comprehensively diagnosed using the Mini International Neuropsychiatric Interview (MINI). The physician in charge of each patient quantified his/her sense of self-confidence in diagnosing the patient with MDD using the self-rating questionnaire in which the score ranged from 1 (not at all confident) to 5 (definitely MDD). Using multiple logistic regression, the demographic and clinical factors of the patients in the low diagnostic confidence group (score less than or equal to 3, n=79) were compared with those in the high diagnostic confidence group (more than 3, n=120). Comorbidity of anxiety disorders (odds ratio (OR), 4.7), absence of remission (OR, 3.6), and non-melancholic features (OR, 3.5) were identified as the most discriminative variables associated with the low diagnostic confidence of MDD. The results show that physicians were unable to confidently diagnose MDD in 40% of the cases, and that comorbidity of anxiety disorders, absence of remission, and non-melancholic features independently predicted the diagnostic uncertainty of MDD.