Background: Switching from one proton pump inhibitor (PPI) to another is common, and may be related to factors other than efficacy and tolerability.
Objectives: The purposes of this study were to describe the incidence of therapeutic switching among PPI users, quantify direct ambulatory medical costs of switching, and characterize the relationship between product switching and variables hypothesized to influence a switch (eg, direct-to-consumer [DTC] advertising, structure of insurance coverage, disease diagnosis).
Methods: This was a retrospective cohort study of health plans using 1998 data. The subjects were employees and dependents with employer-sponsored health insurance contributing to the Medstat Market-Scan administrative dataset. Using a commercially available database to quantify DTC advertising by marketing area, market-specific expenditures were matched to eligible subjects. Among PPI users, we identified those who switched from one product to another (switchers) and compared their utilization and spending with nonswitchers. We then evaluated the relationship between drug use and variables hypothesized to affect switching: DTC advertising, insurance characteristics, patient diagnosis, diagnostic procedures, comorbidities, age, and sex.
Results: The analysis used data for 396,500 individuals from 47 unique markets that were geographically well distributed, with population density similar to that of the United States overall. The sample was also comparable with US census estimates for age and sex among working adults and their dependents. Only 620 (6.3%) of PPI users switched products during the 1998 calendar year. Annual diagnostic and drug costs were >US $400 higher for switchers than nonswitchers. Subjects in areas with high levels of DTC advertising were 43% more likely to switch from lansoprazole to omeprazole than those in the low-expenditure areas. Additionally, patients paying prescription drug copayments >US $5 were 12% less likely to switch from lansoprazole to omeprazole than patients paying lower copayments.
Conclusions: In these privately insured patients using PPIs, product switching was associated with increased treatment costs. DTC advertising and patient cost-sharing were important predictors of product switching.