Diagnostic conversions from major depressive disorder into bipolar disorder in an outpatient setting: Results of a retrospective chart review

Abstract

The aim of the study was to check the stability of a diagnosis of major depressive disorder (MDD) in an outpatient setting, as well as to assess the scope of diagnostic conversions into bipolar disorder (BD). Retrospective chart review of 122 patients with a primary diagnosis of MDD. Diagnostic conversion from MDD into BD was noticed in 40 subjects (32.8%), 25 patients (20.5%) were treatment-resistant. Mean time to the conversion was 9.27±8.64 years. A negative correlation between the age of illness onset and time to diagnostic conversion was observed (-0.41; p<0.05). Earlier onset of MDD was associated with higher risk of diagnostic conversion (<30vs≥30 years of age at onset: 69% vs 28%, p=0.0001; <35vs≥35 years of age: 50% vs 25%, p=0.0065). Treatment-resistance was more prevalent in the BD conversion group (40% vs 11%; p=0.0002). Diagnostic conversion into BD was also related longer duration of treatment received, higher number of illness episodes, and higher number of hospitalizations. Retrospective design of the study. The problem of diagnosis evolution from MDD to BD was observed in about 1/3 of patients, and was associated with treatment-resistance of depression, earlier onset of depression, longer time of treatment, higher number of depressive episodes and hospitalizations. The variables above may be a useful predictor of bipolar diathesis.