TITLE:
Antidepressant Prescribing Patterns for Depressive and Anxiety Disorders in a Singapore Hospital
AUTHORS:
Teck Hwee Soh, Leslie Lim, Herng Nieng Chan, Yiong Huak Chan
KEYWORDS:
Antidepressants, Anxiety Disorders, Depressive Disorders, Augmentation, Combination, Switching
JOURNAL NAME:
Open Journal of Psychiatry,
Vol.5 No.2,
March
6,
2015
ABSTRACT: 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.