Under-utilization of statin medications in patients with peripheral artery disease or cerebrovascular disease

Atherosclerotic vascular disease is a systemic condition associated with significant morbidity and mortality. Coronary artery disease remains the most prevalent and well-recognized clinical manifestation of systemic atherosclerosis, and thus physicians diligently focus on optimal medical therapy to reduce adverse cardiovascular events in this population. Adverse cardiovascular events are also common, and perhaps even more frequent, in patients with peripheral artery disease (PAD) or cerebrovascular disease. Previous data have demonstrated that a significant percentage of patients evaluated by primary care physicians have PAD, ¹ and that patients with PAD are three times more likely to suffer cardiovascular death compared to patients without this disorder. ² Similarly, cerebrovascular disease is also highly prevalent and associated with significant cardiovascular morbidity. ³ It is thus imperative that appropriate management of patients with PAD or cerebrovascular disease includes therapies to reduce the overall incidence of cardiovascular events.

Statins significantly reduce the morbidity and mortality associated with systemic atherosclerosis. Previous observational research has shown that statins reduce both cardiovascular and limb-related adverse events among patients with PAD. ⁴ Similarly, randomized trials have demonstrated a significant reduction in recurrent cardiovascular events among patients with symptomatic cerebrovascular disease that are treated with high-potency statins. ⁵ Based on these data, multi-specialty guidelines from the professional societies recommend statin therapy for patients with PAD or cerebrovascular disease. ⁶ These guidelines were recently amended to recommend high-potency statin therapy for a majority of patients with atherosclerotic vascular disease. ⁷ Despite these recommendations, many patients with PAD or cerebrovascular disease are not appropriately treated with statin therapy. More specifically, numerous observational studies have demonstrated that over one-third of patients with PAD or cerebrovascular disease are not prescribed any statin medications, let alone the high-potency therapies that are currently recommended.^8,9

In this issue of Vascular Medicine, McBride and colleagues extend these findings to the largest integrated healthcare system in the United States, the Veterans Affairs (VA) Healthcare System. ¹⁰ The authors identified patients with PAD or cerebrovascular disease who had been evaluated by primary care physicians using administrative billing codes. By cross-referencing this information with pharmacy data, the authors were able to determine the percentage of patients who were prescribed moderate or high-potency statin therapy. The results are slightly more impressive than in previous non-VA based studies: 79% of patients with PAD were prescribed any statin and 41% were prescribed guideline-recommended therapy. Similar results were obtained for patients with cerebrovascular disease, with 78% of all patients with cerebrovascular disease prescribed statins and 40% prescribed guideline-appropriate dosing of statin therapy. Consistent with prior studies, the proportion of patients receiving these therapies dropped considerably if they did not have concomitant coronary artery disease, suggesting that the recognition of coronary artery disease was a major driver in the decision to prescribe statins. Further, there was significant site level variation (20–28%) in the prescription of statin therapies for both populations, suggesting an opportunity for standardization to improve patient care.

The authors are to be congratulated for again highlighting the deficiencies in medical therapy for patients with PAD or cerebrovascular disease. These deficiencies are particularly profound for patients that do not have concomitant coronary artery disease, emphasizing the importance of continued education to ensure that primary care physicians understand the significant benefits of statin therapy for those with isolated PAD or cerebrovascular disease. Statin prescriptions were significantly more common if implemented after an inpatient hospitalization or a scheduled lower extremity revascularization procedure, suggesting a potential opportunity where preliminary efforts could be focused to improve prescription rates. For example, automated reminders could be developed to recommend statin prescription to such patients during discharge after lower extremity revascularization or a recent inpatient admission. Further, the integrated nature of the VA Healthcare System may make such standardized practices easier to implement. Fortunately, the prescription rates of statin medications within this integrated healthcare system already exceed that in other community based registries, where any statin use has been recorded as low as 33% for some patients with PAD. ⁹ These data suggest that the longitudinal care provided by the VA Healthcare System, coupled with a national electronic medical record, result in better adherence to guideline-recommended therapies in such patients.

The conclusions from these data should be interpreted with several caveats. Although the overall statin prescription rates are similar to or exceed data reported from other registries, the administration of guideline-concordant statin therapy remains abysmal for patients with either PAD or cerebrovascular disease. The data analyzed in the present analysis focuses on fiscal year 2014, a time that spanned publication of the most recent guidelines. Previous research has demonstrated that adoption of new practices often takes several years, thus it is not particularly surprising that primary care physicians had not yet incorporated new guideline recommendations for high-potency statin therapy into their clinical practice. ¹¹ Additional data summarizing the prescription of this therapy in subsequent years may be a more accurate portrayal of contemporary guideline concordance. Further, the analysis of McBride and colleagues does not seek to understand compliance with prescribed statin therapy. Numerous data sets have suggested that compliance with medications is extremely variable, particularly within a population of veterans. ¹² Additional studies would be helpful to determine mechanisms to not only improve guideline-concordant prescription rates, but also means to encourage patient compliance.

Ultimately, these data reinforce the deficiencies in treating systemic atherosclerosis among patients with PAD or cerebrovascular disease. The site-specific variation in prescription rates also highlights the need for well-defined implementation strategies to ensure uniform application of guideline concordant care. Further studies should thus focus on mechanisms to reduce the variation in prescription rates for this vulnerable population, thereby reducing the morbidity and mortality associated with PAD and cerebrovascular disease.