Clinical differences between early and late remission in depressive patients.

Objective: Predicting treatment outcome at an early stage is clinically relevant. The main objectives are: to compare rates of remission after acute and continuation phase treatment and to determine the most common residual symptoms among remitted patients; to compare the residual symptoms in early and late remitted and to identify factors that predict early or faster remission.

Method: It is a prospective, naturalistic, multicenter, and nationwide epidemiological study of 1595 depressive outpatients. Severity of depressive symptoms was assessed with the Hamilton Depression Rating Scale (HDRS) and the Self Rated Inventory of Depressive Symptomatology (IDS-SR(30)). Assessments were carried out after 6-8 weeks of antidepressant treatment and after 14-20 weeks of continuation treatment. Early remitters were defined with an IDS-SR(30) score ≤ 14 at first and second assessment. Late remitters were defined as those scoring IDS-SR(30) >14 at first and IDS-SR(30) score ≤ 14 at second assessment.

Results: 140 subjects (8.8%) were in remission after 6-8 weeks of antidepressant treatment and 862 remitted (59%) after 16-20 weeks of treatment. The mean number of residual symptoms is significantly higher among patients who remit later. Greater differences between early and late remitters were found in the following symptoms: feeling sad, reactivity of mood, interpersonal sensitivity and pleasure/enjoyment. Multivariate analysis showed that only comorbid anxiety disorder is significantly associated with late remission.

Conclusions: Early remitted patients have a better "quality" of remission. Late remission is associated with residual symptoms more related to core depressive symptoms. Residual symptoms in early remitted patients may constitute a new target for the treatment of depression.