Factors influencing drug switching and changes in low-density lipoprotein-cholesterol levels with atorvastatin: a real-world observational study

BACKGROUND: Although generic drugs have been approved with the assurance of interchangeable applications with original drugs, some physicians, and patients still view their efficacy and interchangeability negatively. Using real-world data, we aimed to determine factors that impact switching between drugs that contain the same active ingredient, i.e., atorvastatin, and, in turn, whether this ‘switch’ could alter clinical outcomes. METHODS: Using the National Health Insurance Service senior cohort, a retrospective cohort study was conducted to assess patients who had newly started atorvastatin 10 mg and had at least two records of national health examinations from 2010 to 2014. Drug switching, which was defined as a change in the atorvastatin product administered 90 days before the first and second examinations, was assessed. Greedy propensity score matching (1:2) was performed between switchers and non-switchers to control for potential confounders. Factors influencing switching were analyzed using multivariate logistic regression to estimate odds ratios and 95% confidence intervals (CIs). Changes in low-density lipoprotein-cholesterol (LDL-C) levels attributable to drug switching were evaluated using difference-in-differences regression. RESULTS: A total of 1,588 patients were included, of whom 25.3% switched drugs (1,187 non-switchers and 401 switchers). Compared to patients taking generics before the first examination, those taking the original drugs had a lower odds ratio (0.31; 95% CI [0.21, 0.46]) for subsequent drug switching. A change in medical institution was associated with a significantly higher odds ratio (6.83; 95% CI [4.66, 10.02]). There were no significant differences in LDL-C alterations between switchers and non-switchers (0.42 mg/dL; 95% CI [-2.29, 3.13]). CONCLUSION: The type of first-time drug administered and changes in medical institution can influence drug switching. No significant changes in LDL-C values were observed in the various switching scenarios between the original and generic drugs, suggesting their interchangeable application in real-world clinical practice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12944-023-01903-2.