Mortality rates associated with heart disease have declined in recent years throughout the United States in large part because of evidence-based therapies that help reduce risks of recurrent cardiovascular adverse events. When patients suffer an initial myocardial infarction (MI) and are treated in the hospital, they are prescribed evidence-based cardiovascular therapies. However, simply writing a prescription does not necessarily translate into downstream adherence after they leave the hospital.

Previous research has shown that patient adherence to prescribed therapies is suboptimal with some reports estimating that more than 25% of patients do not fill their prescriptions within a week of being discharged after an acute MI. “Medication non-adherence after MI is a widely recognized problem in healthcare and has been linked to worse patient outcomes and higher healthcare costs,” says Robin Mathews, MD. “A better understanding of the modifiable factors that contribute to non-adherence may help us develop interventions to help optimize patient outcomes.”


Longitudinal Observations

In a study published in Circulation: Cardiovascular Quality & Outcomes, Dr. Mathews and colleagues assessed medication adherence among 7,425 acute MI patients who were treated with PCI at 216 U.S. hospitals over a period of 2 years. The institutions involved in the study participated in TReatment with ADP receptor iNhibitorS: Longitudinal Assessment of Treatment Patterns and Events after Acute Coronary Syndrome (TRANSLATE-ACS), a longitudinal observational study of PCI-treated MI.

“There are many reasons why medication adherence is poor among cardiac patients,” Dr. Mathews says. “TRANSLATE-ACS is unique in that it allows us to evaluate both patient and provider factors that may contribute to non-adherence.” TRANSLATE-ACS provides data that can be used to determine the incidence and degree of cardiovascular medication adherence as well as subsequent mortality and readmissions. TRANSLATE-ACS assessed adherent behaviors using the validated, eight-question Morisky Medication Adherence Scale (MMAS). The MMAS was used to stratify patients into self-reported high, moderate, and low adherence groups.


Important Themes

“As early as 6 weeks after discharge, about one-third of patients who survived their MI did not consistently take medications as prescribed,” says Dr. Mathews (Table). One-third of low adherence patients reported missing doses of antiplatelet therapy at least twice a week after PCI. This is of particular concern because non-adherence to antiplatelet therapy after PCI is associated with increased risk for stent thrombosis. Among the patients who were least likely to take their medication, most cited forgetfulness and about 20% reported not telling their physician that they had stopped taking drugs due to side effects.

The investigators found a trend toward worse clinical outcomes among those patients who were less adherent to prescribed therapies, however this did not reach statistical significance. Also, data were not used in cases when patients died within 6 weeks of their MI, meaning it is possible that early medication non-adherence was underreported.

Several factors were associated with a higher likelihood of medication non-adherence in the study, most notably signs of depression and patient-reported financial hardship due to medication expenses. “Regardless of the reason, patient non-adherence to medications after an MI is associated with poor outcomes, including repeat hospitalizations, disease progression, and lower survival rates,” Dr. Mathews says. Patients were more likely to be adherent to their MI drug regimens at 6 weeks if they had follow-up appointments made before they were discharged and had a provider explain potential side effects of their medications.


Significant Implications

In the days following an MI, Dr. Mathews says it is important for clinicians to consider barriers to adherence, such as factors like poor health literacy or cost concerns. “There is no one-size-fits-all approach that will help determine at-risk patients because no two patients are the same,” he says. “Therefore, patient education and pre-discharge planning that is tailored to the individual are critical to optimizing adherence and clinical outcomes.”

Dr. Mathews says it is important to open the communication lines and find out why doses are skipped or why patients are not filling their prescriptions. The transition from hospital to home was identified as an important period where interventions can improve adherence. “There are no standardized protocols for discharging patients after an MI,” he says. “Physicians need to take the lead and discuss the role of medications in preventing another MI. In addition, we should also discuss any possible side effects and inquire about any about financial issues patients may have. We need to fine tune our efforts to assess perceived barriers to adherence so that we can ultimately improve outcomes.”