Pharmacogenetic Testing in the Outpatient Setting in Switzerland: A Descriptive Study Using Swiss Claims Data

Background In Switzerland, consumers are exposed to drugs with pharmacogenetic (PGx) recommendations in 78% of cases. Pre-emptive PGx testing for seven drugs (abacavir, carbamazepine, 6-mercaptopurine, azathioprine, 5-fluorouracil, capecitabine, and irinotecan) has been covered by basic health insurance since 2017. PGx testing for other drugs is only covered if it is reactive and prescribed by a clinical pharmacologist. No data are yet available on the implementation of PGx testing in the outpatient setting. Aim The objective of this study was to determine the prevalence of ambulatory PGx testing in the Swiss population, to characterize PGx-tested individuals, and to identify the most commonly used drugs before and after PGx testing. Methods We assessed the prevalence of PGx testing in Switzerland and characterized individuals who underwent PGx testing between 2017 and 2021 using claims data from a large health insurance company. Results Of 894,748 individuals registered for the entire study period, only 817 (0.09%) underwent PGx testing. Those who underwent PGx testing were more frequently female and claimed more drugs and PGx drugs than those who did not undergo PGx testing. The drugs used before and after PGx testing differed, and fewer drugs with reimbursement for pre-emptive PGx testing were included before PGx testing. Conclusion In Switzerland, personalized pharmacotherapy has the potential to be improved, as only 0.09% of the studied population underwent PGx testing, despite 77.4% claiming PGx drugs.