Residual symptoms of depressive disorder are major predictors of relapse of depression and lower quality of life. This study aims to investigate the prevalence of residual symptoms, relapse rates and quality of life among Thai patients with depressive disorders.

Hamilton Rating Scale for Depression (HAM-D) and EQ-5D were used to measure the symptoms of depression and quality of life, respectively. Prevalence of residual symptoms of depression was collected. Regression analysis was administered to predict relapse and patients’ quality of life at the 6 months post-baseline.

Two hundred and twenty-four depressive disorder patients were recruited. Most of patients (93.3%) had at least one residual symptom, and the most common residual symptom was anxiety symptoms (76.3%; 95% CI, 0.71 to 0.82). After 3 months post-baseline, 114 patients (50.9%) were in remission and within 6 months, 44 of them (38.6%) relapsed. Regression analysis showed that residual insomnia symptoms were significantly associated with these relapse cases (OR = 5.290, 95% CI, 1.42 to 19.76). Regarding quality of life, residual core mood and insomnia significantly predicted the EQ5D scores at 6 months post-baseline (B = −2.670, 95% CI, −181 to −.027, and B = −3.109, 95% CI, −172 to −.038, respectively).

Residual symptoms are common in patients receiving treatment for depressive disorder and were found to be associated with relapses and quality of life. Clinicians need to be aware of these residual symptoms when carrying out follow-up treatment in patients with depressive disorders, so that prompt action can be taken to mitigate the risk of relapse.

The authors have not supplied their declaration of competing interest.