Medication non-adherence in CVD

Medication non-adherence in CVD

A study published in the August issue of the British Medical Journal found that the prevalence of non-adherence in chronic conditions is around 50%. In patients with cardiovascular disease (CVD), medication non-adherence is extensive, resulting in significant repercussions, especially in the period immediately following an acute CV event.

A cohort study in Ontario found that 27% of patients did not fill discharge prescriptions one week after hospitalisation for acute coronary syndrome (ACS), and these patients had increased one year mortality.

At one month following ACS, 34% of patients discharged from hospitals had stopped taking at least one of aspirin, beta-blocker, or statin therapy. When looking at one to two years following ACS, non-persistence reaches 55%60%, with further reductions seen over 10 year follow-up.

Improved medication adherence following acute myocardial infarction (AMI) has been associated with a reduction in major vascular events and revascularisation at one year as well as lower medical costs, major adverse cardiovascular events (MACE), and mortality.

Non-adherence to dual antiplatelet therapy following AMI has been shown to increase the risk of stent thrombosis and mortality at one year. High rates of non-adherence persist despite the growing research and resource efforts directed toward this problem.

Barriers to medication adherence

Understanding the factors that affect adherence to medications is critical in the evaluation of interventional strategies. These factors have been broadly grouped into five categories by the World Health Organization: patient related factors, socioeconomic factors, health team and system factors, therapy factors, and condition related factors:

1. Patient factors: A patient’s personal beliefs regarding their illness, such as the belief that medications are unnecessary to control their condition, or that medications will cause side effects, influence their adherence to prescribed treatment plans. An individual’s health literacy, cognitive ability, and degree of forgetfulness, have each separately correlated with medication adherence, with forgetfulness having previously been attributed to more than one third of all cases of non-adherence. These patient-level factors are clinically underrecognized but are important causes of non-adherence.

2. Socioeconomic influences: Individuals categorised as having a lower socioeconomic status (SES) have been associated with lower medication adherence, as seen in a systematic review which finds this relationship among patients with a first AMI. This is partly a result of medication cost, with one in eight patients with CVD reporting cost related non-adherence. Beyond income, low SES has been associated with decreased access to providers and pharmacies, as well as less coverage for prescription medications. Socioeconomic factors have a profound influence on health outcomes, and poor medication adherence is another mechanism by which lower SES contributes to adverse health outcomes.

3. Structure of the healthcare system: This can negatively influence a patient’s adherence to medications. Poor communication between inpatient and outpatient care teams, between specialists in different health systems, and between providers and pharmacists, often leads to poor communication with patients, ultimately leading to non-persistence owing to therapy confusion.

4. Prescribed therapies and the conditions for which they are prescribed: Many medications have unwanted side effects, require additional monitoring, and serve as a consistent reminder of the patient’s illness, all factors that might reduce patient persistence. Further, complicated dosing regimens can lead to inconvenient administration times and contribute to forgetting to take medications. Individuals with multiple medical conditions or conditions that require a large pill burden must adhere to complex regimens and may experience medication interactions and polypharmacy leading to non-adherence. The individual causes of a patient not adhering to prescribed medical therapy are not uniform and have multiple contributing and intertwined factors.

Grouping them into patient related factors, socioeconomic factors, health team and system factors, and therapy and condition related factors helps to organise approaches to improve adherence.

Approaches to improve adherence

Educational interventions: Interventions focused on this Improving a patient’s health education aspect posit that if patients fully understand the extent of their illness and the benefits of the prescribed therapy, they would be more engaged in the therapy and therefore more likely to be adherent.

Technology reminder interventions: Forgetting to take medications is a significant cause of medication non-adherence and recent technologies have provided a cheap and relatively simple way to provide reminders. The use of mobile phone calls, text messages, and applications can improve adherence, albeit without demonstrable clinical outcome improvement. Use of these techniques should be tailored to those patients who have difficulty remembering to take medications and are comfortable navigating the technology.

Cognitive behavioural and motivational interventions: Some patients are less motivated to take medications regularly and changing this behaviour can be challenging. Motivational interviewing, behavioural feedback, and social support have been explored as methods to collaboratively change behaviours surrounding medication adherence. Other counselling techniques explored include positive-affect induction and self-affirmation, which focus on having patients identify moments that make them happy and proud. Improvements in medication adherence have been seen when family members are involved to provide social support.

Cost of medication and financial incentive interventions: The cost to obtain medications can act as a major barrier to adherence and persistence, especially in healthcare systems that have a higher patient cost burden. Interventions that reduce the cost of medications or provide financial incentives for taking medications have been explored as methods to improve adherence. Evidence suggests that easing out-of-pocket costs for medications and financial incentives can improve patient adherence. In terms of the latter a study looked at the impact on adherence to medicine in which physicians were awarded monetary incentives per enrolled patient meeting goals for low density lipoprotein cholesterol and patient incentives were distributed through daily lotteries tied to medication adherence. Patients in the shared physician-patient incentives group had significantly higher mean medication adherence compared with control (39% versus 27%).

Healthcare team members: Healthcare team members can be utilised to increase interaction with patients in the community, but these are generally resource and time intensive interventions that require substantial investments from health systems. Trials have generally shown modest improvements in medication adherence and clinical outcomes with these interventions.

Fixed dose combination therapy: Polypharmacy and complicated dosing regimens contribute to poor medication adherence, and polypills have been employed to address this barrier. Evidence suggests a substantial improvement in clinical outcomes can be obtained with this strategy. While there are difficulties with matching patients to a given polypill and changing doses of individual elements of a polypill, this is an intervention that can be sustained long-term without substantial cost or effort in the appropriately selected patient.

Multifaceted interventions: Many patients have multiple barriers to medication adherence, making a single focus of intervention less likely to be effective. Strategies combining multiple interventions have generally managed to improve measured adherence.

Conclusion

Medication non-adherence in CV medicine is a preventable cause of substantial morbidity and mortality. Improvements in medication adherence that translate to improved clinical outcomes could lead to significant reductions in healthcare costs.

Reference

Simon ST, Kini V, Levy AE and Ho PM. Medicationadherence in cardiovascular medicine. BMJ, 2021. SF