Characteristics and differences in treatment outcome of inpatients with chronic vs. episodic major depressive disorders

Background Approximately 20–30% of patients with Major depressive disorder (MDD) develop a chronic course of their disease. Chronic depression is associated with increased health care utilisation, hospitalisation and a higher disease burden. We identified clinical correlates and differences in treatment response of chronic MDD (cMDD) patients compared with non-chronic episodic depression in a huge sample of depressive inpatients. Methods Data were collected from 412 inpatients who had been diagnosed with a major depressive episode (MDE; according to ICD-10) and scored 15 or higher on the 21-item Hamilton Depression Rating Scale (HRSD-21). All subjects were participants in the German Algorithm Project, phase 3 (GAP3). Patients who were diagnosed with a MDE within the last two years or longer (herein referred to as CD) were compared with non-chronic depressive patients (herein referred to as non-CD). CD and non-CD patients were assessed for the following: psychosocial characteristics, symptom reduction from hospital admission to discharge, symptom severity at discharge, remission and response rates, and pharmacological treatment during inpatient treatment. The primary outcome measure was the HRSD-21. Results 13.6% ( n =56) of patients met the criteria for chronic depression. Compared with non-CD patients, patients with CD showed increased axis I comorbidities (74% vs. 52%, χ 2 (1)=7.31, p =.02), a higher level of depressive symptoms at baseline and discharge, increased duration of inpatient treatment (64.8 vs. 53.3 days; t =2.86, p =.03) and lower response (HRSD: 60.0% vs. 72.0%; χ 2 (1)=3.61, p χ 2 (1)=3.56, p =.04) and remission rates (BDI 17.9.% vs. 29.7%; χ 2 (1)=3.42, p =.05. However, both groups achieved a comparable symptom reduction during inpatient treatment. The prescribed pharmacological strategy had no significant influence on treatment outcome in patients with CD. Conclusion Inpatients with CD show higher symptom severity, lower response and remission rates and a longer duration of inpatient treatment, although they achieve comparable symptom reduction during treatment. These findings support the need to recognise CD and its defining characteristics as a distinct subclass of depression.