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Barriers to Antiplatelet Therapy Use

Clinician Barriers
A number of factors may contribute to underprescription of antiplatelet therapies in ACS patients, including lack of awareness or familiarity with guidelines, competing guidelines, complex medical regimens, lack of outcome expectancy, and clinical inertia.11,12 The complexity and volume of current guidelines could inhibit implementation within the time and money constraints of primary care practices. In the Reassessing European Attitudes About Cardiovascular Treatment (REACT) study, 23% of primary care physicians from the United Kingdom who were surveyed felt the guidelines were too difficult to implement in primary care, and another 23% felt there were too many guidelines.13 Moreover, as more data become available from clinical trials, guidelines are updated, and the updated guidelines need to be adequately publicized so clinicians become aware of them as soon as they are released.
Another factor contributing to underprescription of antiplatelet and other risk reduction therapies may be subjective underestimation of patient risk and likely treatment benefit, as revealed in a recent prospective, multicenter, Canadian ACS registry II study.14 This study asked clinicians why they did not prescribe evidence-based treatments (EBTs) during hospitalization for patients with non–ST-segment elevation (NSTE) ACS. The most common reason given by clinicians for not prescribing EBTs was “not high-enough risk” or “no evidence/guidelines to support use.” However, GRACE scores of patients not treated for this reason were often similar to or higher than those of patients prescribed such treatment. Furthermore, 1 year after hospitalization, 77% of patients not on optimal ACS treatment at discharge remained without optimal treatment.14
Poor communication between primary care clinicians and cardiologists can hinder optimal use of preventive therapies.15 After in-hospital initiation of antiplatelet therapies, the cardiologist may not relay the need for continuation or the intended duration of these therapies to the primary care clinician managing the patient postdischarge. In addition, the cardiologist may consider initiation of CAD risk reduction therapies, such as lipid-lowering and antihypertensive therapies, the responsibility of the primary care clinician, whereas the clinician may assume therapy would have been initiated by the cardiologist had it been needed. The nature of outpatient practice also may interfere with guideline adherence, as patients and clinicians may focus on acute care concerns while neglecting secondary preventive issues.16

Clinician Barriers to Guideline-Recommended ACS Therapies: Lessons From the ACS Management PI Program

NPs and PAs who participated in the ACS Management PI Program reported that most of their patients were prescribed guideline-recommended therapies for long-term management of ACS at discharge (Figure 3A). Prescription rates were highest for β-blockers (87.4%) and lowest for angiotensin-converting enzyme (ACE) inhibitors (67.4%).
Treatment eligibility of patients who did not receive prescriptions at discharge was not always defined. The presence of contraindications was cited for 22.2% (10/45) of patients not prescribed dual antiplatelet therapy, 36.4% (8/22) of patients not prescribed β-blockers, and 22.8% (13/57) of patients not prescribed ACE inhibitors. For 58.3% (14/24) of patients not prescribed lipid-lowering therapy, the lipid profile was considered to be within acceptable limits. For the remaining patients not prescribed guideline-recommended therapies, physicians considered the treatment unnecessary (for unspecified reasons) or the reason was unknown.
When guideline-recommended treatments were not prescribed, direct communication between clinicians responsible for long-term management of ACS and cardiologists responsible for in-hospital care occurred within 7 days of discharge for only about half the patients. Direct communication rates ranged from 45.5% for patients not prescribed β-blockers to 61.4% for patients not prescribed ACE inhibitors (Figure 3B).

Patient Barriers

Evidence suggests that patient attitude is a significant factor in poor adherence to guideline-recommended therapies, with many patients exhibiting poor adherence to lifestyle changes or medication regimens.17 Medication nonadherence is an unrecognized risk factor for CV disease. The estimated yearly cost of medication nonadherence is $396 to $792 million.18
Although the reasons for nonadherence to prescribed medications are heterogeneous, patients’ perception of the need for therapy plays an important role in adherence.19,20 Lack of education about the rationale for and importance of continuing antiplatelet treatment may lead to delays in filling an antiplatelet prescription after hospital discharge,21 or premature discontinuation of antiplatelet therapy,22,23 resulting in an increased risk of adverse outcomes. In a recent retrospective cohort study of patients discharged from 3 large integrated healthcare systems after DES implantation, 1 in 6 patients delayed filling the index antiplatelet prescription after discharge.21

Patient Adherence to Guideline-Recommended ACS Therapies: Lessons From the ACS Management PI Program
Only 59.7% (86/144) of ACS patients were contacted within 3 days of hospital discharge and reminded to fill prescriptions for prescribed treatments. Contact rates by event type were similar: 66.0% of patients with UA, 53.2% of patients with NSTEMI, and 59.1% of patients with STEMI were reminded to fill their prescriptions.
Reported rates of adherence to prescribed therapies at 90-day follow-up are shown in Figure 4. Overall, rates of adherence were higher for pharmacologic therapies than for nonpharmacologic therapies, including cardiac rehabilitation, smoking cessation, weight reduction, and dietary modifications. The highest adherence rates were for ACE inhibitor (88.1%) and dual antiplatelet (87.7%) therapies. The lowest adherence rates were for smoking cessation (57.1%) and dietary modifications (62.2%).
When patients did not adhere to prescribed therapies during the 90-day follow-up period, NPs and PAs were asked whether they discussed the treatment nonadherence with the patients’ primary care physician or cardiologist. Nonadherence follow-up rates (ie, percentage of NPs and PAs who reported discussing their patients’ treatment nonadherence with the primary care physician or cardiologist) varied considerably by treatment: dual antiplatelet, 55.2%; β-blocker, 100%; ACE inhibitor, 85.7%; lipid-lowering, 83.3%; cardiac rehabilitation, 70.0%; smoking cessation, 89.5%; weight reduction, 64.3%; and dietary modification, 65.2%.