The effects of continuous antidepressant treatment during the first 6 months on relapse or recurrence of depression

To examine whether continuous antidepressant treatment during the first 6 month reduces the risk of relapse/recurrence of depression in South Korea.

We used National Health Insurance Data covering the period from 2001 through 2004. The study population consisted of 117,087 adult patients who received antidepressants after being diagnosed with depression. The continuous antidepressant was defined as evidence of antidepressant prescriptions for 75% of the first 6 months of treatment. Relapse or recurrence during the next 18-month period was defined by evidence of a new episode requiring antidepressant treatment, psychiatric hospitalization, electroconvulsive therapy, emergency department visit or attempted suicide. We compared the relapse/recurrence rate during the 18-month follow-up period in patients receiving continuous treatment and those who discontinued early using a Cox's proportional hazard model.

Patients receiving continuous antidepressant treatment experienced a lower risk of relapse/recurrence (Hazard ratio: 0.42, 95% CI: 0.40-0.44). Three or more follow-up visits in the first 3 months also reduced the risk of relapse/recurrence. Factors associated with a significant increase of relapse/recurrence were comorbid medical illness, anxiety disorder, and alcohol abuse. The small benefit of SSRIs was appeared only in the early discontinued treatment subgroup, not in the continuous treatment subgroup.

We were not able to consider the antidepressant utilization pattern.

Continuous antidepressant treatment and frequent follow-up visits during the acute phase were associated with a significant reduction in the likelihood of relapse or recurrence of depression. Our results provide important evidence on the effectiveness of antidepressant treatment in South Korea.