Treatment Failure With Atorvastatin After Change From Rosuvastatin to Atorvastatin

Results

Three hundred twenty-three patients were identified and reviewed as converted from rosuvastatin to atorvastatin during the study period with no prior use of atorvastatin. Of the 323 charts that were reviewed, 195 patients met the study inclusion criteria and were analyzed for rate of treatment failure in terms of lipid goals and rate of AEs. Twenty of 195 patients (10.3%) were no longer at their LDL-C goal after conversion from rosuvastatin to atorvastatin. Of those 195 patients, 29 (14.9%) experienced an adverse drug reaction (ADR) as a result of atorvastatin treatment that was severe enough to result in discontinuation of the drug and switching the patient back to the originally prescribed dose of rosuvastatin. Figure 1 illustrates the number of patients and documented atorvastatin ADRs. The most common ADR documented to atorvastatin was myalgias (8.2%).

The average change in lipid levels was calculated and atorvastatin therapy was found to result in clinically insignificant changes to the lipid panel (Table 2). A 2-tailed paired t test was used to assess the statistical significance of these changes. Atorvastatin therapy resulted in an average decrease of LDL-C by 5.0 mg/dL (P < .01) in comparison to previous therapy with equivalent rosuvastatin dose. Other noted changes to lipid profile after formulary conversion included TG reduction by 2 mg/dL (P = .69), TC increased by 0.58 mg/dL (P = .80), and HDL-C reduction by 4.66 mg/dL (P < .01).

Although the decrease in LDL-C and HDL-C as a result of the formulary change was found to be statistically significant, they are not thought to result in a clinical difference. Clinically and statistically insignificant changes in liver enzymes and CPK were also discovered as a result of atorvastatin therapy conversion (Table 3). Atorvastatin therapy resulted in an averaged decrease of aspartate aminotransferase by 2.2 IU/L (P = .19) and an increase in alanine aminotransferase by 1.4 IU/L (P = .47). Average change in CPK was -6 IU/L (P = 89).

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Discussion

Lipid levels were found to be mostly unchanged and remained at therapy goals, demonstrating use and appropriate equivalent dosing of rosuvastatin and atorvastatin following the formulary conversion defined in Table 1. Documented ADRs were minimal, indicating the ingredient conversion was well tolerated overall by our patients. Following the release of the 2013ACC/AHA guidelines, many patients in the VA required treatment with high-potency statins such as rosuvastatin and atorvastatin. Given the volume of statin prescriptions in the VA and the significant potential for providing the most cost-efficient lipid therapy (Table 4), the formulary conversion from rosuvastatin to atorvastatin was warranted.

Limitations

There are several limitations for extrapolating results from this study to the general population. Due to the retrospective design of the study, no formal assessment of adherence was conducted. A prospective trial, with a researcher monitoring refills and tablet counts would be more accurate to ensure patients adherence with statin therapy.

Many of the patients that were included in the formulary conversion did not have follow-up laboratory work at the time of this study and were therefore excluded, leading to a smaller study population. A larger study population with a similar study design may be able to detect more significant correlations.

There are also several potential complications in regard to formulary conversions, including the inability to ensure the exact period that the patient switched therapies. During the conversion of rosuvastatin to atorvastatin at HVAMC, an attempt was made to minimize this confounder by converting patients on request for a refill of their rosuvastatin therapy. Last, all 185 patients that were studied were male; therefore, it is difficult to extrapolate these results for female patients.

Conclusions

This study shows that the conversion of patients from rosuvastatin therapy to atorvastatin was effective when it targeted a specific LDL-C goal or specific reduction in LDL-C. A similar conversion would likely lead to lower drug costs for many other health systems. Additional studies will be necessary given the recent changes in the national lipid guidelines. Furthermore, studies will be needed to assess concrete clinical endpoints (cardiovascular mortality, all-cause mortality, and cardiac events).

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Author disclosures
The authors report no actual or potential conflicts of interest with regard to this article.

Disclaimer
The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the U.S. Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.