Objectives:
Misdiagnosis of bipolar disorder may result in a non-optimal treatment, higher servicecosts and increase in the patient’s suffering and risk of suicidal behavior. Lack of clinically approved and suitable for widely use biomarkers of BD led clinicians to focus on clinical course and symptomatology of depression in BD. The aim of this study was the retrospective evaluation of symptomatic differences and symptoms stability between MDD and BD patients during three subsequent depressive episodes in the inpatient setting.

Methods:
Retrospective chart review of 99 patients with diagnosis of MDD and BD during three subsequent depressive episodes. Chi-squared test and logistic regression was used to analyze the symptomatic profile. Cohen’s kappa value used to estimate symptoms stability.

Results:
Statistical differences were observed in the case of 7 out of 22 depressive symptoms. Somatization (pain and non-pain complains), psychomotor agitation and pathological guilt were more frequent in MDD patients. Anhedonia, attention deficit, and suicidal ideation were more frequent in BD group. In MDD group relatively highest symptom stability was observed for somatization, middle insomnia, early wakening, and attention deficit. In BD group relatively highest symptom stability was observed for delusions, somatization (pain and non-pain complains), initial and middle insomnia, memory disturbance, psychomotor retardation, and pathological guilt.

Conclusions:
The observed symptomatic differences may be an additional factor of MDD/DB differential diagnosis. Lower than previously reported symptoms stability highlights the need to evaluate more than one depressive episode in differential diagnosis.