Author(s)

Teck Hwee Soh¹, Leslie Lim^1*, Herng Nieng Chan¹, Yiong Huak Chan²

¹Department of Psychiatry, Singapore General Hospital, Singapore.
²National University Health System, Singapore.

Objective: Although antidepressants are the recommended first-line pharmacological treatments for depressive and anxiety disorders, their prescribing patterns have not been studied in Singapore. We investigate antidepressant prescription patterns for outpatients with depressive and anxiety disorders in a general hospital in Singapore. We hypothesize that intolerance to side effects and lack of efficacy may contribute to medication switching, and that initiation of antidepressant therapy is not easily tolerated. Methods: A retrospective review of the casenotes of outpatients was carried out between January 2013 and December 2013. A total of 206 patients were randomly selected. The study was approved by the hospital’s institutional review board. Data analysis was carried out using SPSS version 18. Results: There were more females than males (ratio 1.7:1) with a mean age of 50.6 ± 15.2 years. Depressive disorder, comprising 50% of the sample, was the most frequent diagnosis followed by anxiety disorder (27.2%), mixed anxiety-depression (16%) and adjustment disorder (5.8%). Almost all patients (97.1%) were prescribed antidepressants, the most common being selective serotonin reuptake inhibitors (SSRI) (75.5%), followed by the noradrenaline and specific serotonin antidepressant (NaSSA) (13.5%) and tricyclic antidepressants (TCA) (8.5%). Patients prescribed SSRIs tended to be younger and better educated (p = 0.0005). More than half of the patients (52.1%) required antidepressant switching mainly due to lack of efficacy and intolerance of side effects. Combination therapy was prescribed for 17% of patients with SSRI-NaSSA, the most preferred combination. Nearly a quarter (23.8%) patients required augmentation therapy with atypical antipsychotics. Combination (p = 0.024) and augmentation (p = 0.033) were utilized more often for depression than for anxiety disorders. Conclusion: Antidepressant medications are commonly prescribed for depression and anxiety disorders. The main reasons for switching antidepressants were intolerance and lack of efficacy. That about half of the patients reported side effects necessitating medication change confirmed our hypothesis that antidepressant therapy was not easy to initiate. This has important implications for treatment adherence and outcome.

Antidepressants, Anxiety Disorders, Depressive Disorders, Augmentation, Combination, Switching

Soh, T. , Lim, L. , Chan, H. and Chan, Y. (2015) Antidepressant Prescribing Patterns for Depressive and Anxiety Disorders in a Singapore Hospital. Open Journal of Psychiatry, 5, 144-152. doi: 10.4236/ojpsych.2015.52016.