A drug utilization review on antidepressants

Laher, Safiyyah
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The introduction of Selective Serotonin Reuptake Inhibitors (SSRIs) has lead to a considerable increase in global antidepressant prescriptions. This increase has been driven by the SSRIs favourable adverse effect profile and increased safety in overdose compared to the older generation of drugs. This increase has created substantial controversies. Questions have been raised on the efficacy of treatment of depression and anxiety, suicidality rates and tolerability of drugs. Despite these controversies, usage of antidepressants remains high. This research aims to shed light on current antidepressant prescriptions and compare these to local and international usage patterns and treatment guidelines. Differences in usage between antidepressants are also assessed. Two datasets (A and B) were acquired from different medical data warehousing companies. Each dataset comprised of 1 year’s medical records from healthcare practitioners subscribed to the respective company (Dataset A from 2009, Dataset B from 2011). Data included a unique patient number, age, gender, treatment code, ICD-10 code and treatment date. Microsoft Excel was used to filter the data and isolate patients treated with an antidepressant and a cluster analysis was performed to group antidepressants together. Simple descriptive statistics were determined. Data was analysed using STATA (v10.0). Statistical significance was determined using Pearson’s chi-squared tests, theMann Whitney U test and logistic regression. Significance levels were set at p<0.05. For dataset A, n=9213 and B, n=1244. The most frequently dispensed antidepressant was amitriptyline (A:67.75%, n=6 242, B: 64.06% n=797). The mean age of patients was 43.8613.81 and 46.2713.07 respectively. The type of antidepressant used was significantly associated with ICD-10 code, psychiatric condition and categorical age (p<0.0001). The mean number of antidepressant prescriptions per patient were A:2.953.77 and B:2.572.47. Duration of treatment was related to age, ICD-10 code and psychiatric condition (p<0.0001). This research shows that amitriptyline accounts for a majority of prescriptions because of its varied indications for use. The determinants of the type of antidepressant used showed that patients with a psychiatric condition were more likely to receive a newer antidepressant and patients with a pain condition were more likely to receive an older antidepressant. Reasons for poor adherence to treatment and determinants of duration of treatment are discussed.