(SLB-055) Antidepressant Drug Switching in the Swiss population with a focus on Escitalopram and drugs with pharmacogenetic dosing guidelines: A drug utilization study using claims data

Background: Depression affects around 10% of the Swiss population. While SSRIs are commonly prescribed, only 30-40% of patients achieve remission. Pharmacogenetic (PGx) factors may explain part of this high rate of SSRI treatment failure.

Objectives: The aim of this study was to assess antidepressant (AD) switching among Swiss patients using escitalopram, focusing on whether they switched to ADs with PGx dosing guidelines (PGx AD) or ADs without PGx dosing guidelines (non-PGx ADs)

Methods: Using Swiss health insurance claims data from the Helsana Group, we identified all patients with escitalopram claims between July 2020 and June 2022. Switching was defined as a claim for a different AD within 100 days of an escitalopram claim. Pharmacogenetically (PGx) relevant antidepressants were defined as antidepressants with a dosing guideline on The Pharmacogenomics Knowledgebase (PharmGKB), an NIH-funded resource that collects, curates, and disseminates knowledge about clinically actionable gene-drug associations and genotype-phenotype relationships. Switching rates were stratified according to demographic and clinical characteristics. Multivariable logistic regression was used to identify the factors associated with AD switching.

Results: 41 275 patients received escitalopram plus another antidepressant. Of these, 2 638 (6.4%) switched to a different AD, with only 35.4% switching to a PGx AD. Men (OR 1.16, 95% CI 1.06–1.26), younger adults aged 20-39 years (OR 1.14, 95% CI 1.02–1.27) exhibited higher switching rates. Patients on antipsychotic medications (OR 0.86, 95% CI 0.81 - 0.97) were less likely to switch. . Individuals younger than 20 years old (OR 1.66, 95% CI 0.98–2.80) were more likely to switch to PGx AD whereas the elderly (OR 0.54, 95% CI 0.41–0.70) and men (OR 0.78, 95% CI 0.65–0.93) were less likely to switch to PGx AD.

Conclusions: In conclusion, approximately 6.4% of the individuals switched from escitalopram to non-PGx AD. Further studies incorporating genetic data are required to assess the potential benefits of PGx-guided AD-prescriptions.