Patient adherence: an opportunity for improving cardiovascular disease outcomes




Patient adherence: an opportunity for improving cardiovascular disease outcomes


Key Messages 

  • The rapid increase in cardiovascular disease determinants such as ageing are transforming healthcare needs in developing countries. 
  • Low cardiovascular medication adherence is associated with significantly worse outcomes, including increased risk of mortality, morbidity and healthcare costs.
  • Global cardiovascular non-adherence rates are greater than 50% in developing countries, indicating a significant opportunity to improve healthcare outcomes.

Cardiovascular Diseases Are Transforming Healthcare Needs.

Changing demographics and lifestyle trends are driving an unprecedented increase in the prevalence of chronic conditions, affecting nearly half of all adults and almost 10% of children worldwide.1 Cardiovascular diseases pose a particular threat, as the leading cause of mortality globally and disproportionately affecting low- and middle-income countries.2

Cardiovascular disease determinants, such as population ageing, are manifesting dramatically in these countries: the proportion of the population over age 65 is expected to double in just two decades in Brazil, a phenomenon which took over a century in France.3 Amid these shifts, pharmacological treatments are increasingly important as effective disease management solutions but require adherence to be effective.

Non-adherence Among Cardiovascular Patients Is Significant, Even After Acute Events.

Adherence for cardiovascular treatments varies by drug class and depends on whether the treatment is indicated for either primary or secondary intervention, but they generally approximate the global adherence rate of 50%, meaning that roughly half of prescribed medications are not taken. Studies indicate a global cardiovascular adherence of 40% to 60%,4 with rates expected to be lower in developing countries.5,6

Even acute cardiac events do not necessarily improve adherence. In a study of more than 4500 post-myocardial infarction (MI) patients, 18% did not once fill their cardiac medications in the 4 months after discharge from hospital (an example of non-fulfillment). In a separate cohort of more than 22,000 post-acute coronary syndrome patients, 60% discontinued their statin medication within 2 years of hospitalization (non-persistence).7 Thus, non-adherence to cardiovascular treatments is significant.

"Medication adherence is defined as “the degree to which the person’s behavior corresponds with the agreed recommendations from a health care provider”"

Poor adherence is associated with worse outcomes and higher costs.

Low adherence is a problem because it is linked to poor control of cardiovascular disease risk factors such as hypertension and cholesterol. It is also associated with worse outcomes; survivors of acute MIs who had poor and intermediate adherence to statins had 25% and 12% increased risk of mortality, respectively, compared to survivors with high adherence.7 These outcomes are associated with annual non-adherence costs as high as $19K per cardiovascular disease patient.1 Given the magnitude of what is at stake in terms of outcomes and costs, the adherence challenge must be addressed.

Adherence Behavior is Complex, Making it difficult to evaluate and influence. 

Medication adherence is defined as "the degree to which the person’s behavior corresponds with the agreed recommendations from a health care provider", and is considered to have three components, commonly referred to as fulfillment, persistence and compliance. 


Refers to the treatment prescription being filled by the patient.


Refers to the treatment being taken for the intended duration.


Refers to the intended treatment regimen, including intended timing and dosage.6

The complexity of patients’ behavior regarding their medication makes real adherence levels and impact difficult to quantify. Proxies developed to assess adherence in real-world studies include the mean Medication Possession Ratio (MPR) and the Proportion of Days Covered (PDC).

Medication Possession Ratio

is commonly defined as “the proportion (or percentage) of days’ supply obtained during a specified time period or over a period of refill intervals” and can be calculated using various methods.

Proportion of Days Covered

allows us to go further as it refers to the number of days when the drug was properly taken divided by the number of days in the study period.

Adherence in the case of any individual patient via either of these measures is generally defined as a ratio of at least 80%.9 

Adherence is complex; maintaining high adherence levels requires that patients continuously make choices and adjust their behavior to overcome the various challenges to taking their treatment. 

1. Cutler, Rachelle Louise et al. “Economic impact of medication non-adherence by disease groups: a systematic review.” BMJ open vol. 8,1 e016982. 21 Jan. 2018, doi:10.1136/bmjopen-2017-016982
2. “Cardiovascular Diseases (CVDs).” World Health Organization, World Health Organization, 17 May 2017,
3. Global Health and Aging. World Health Organization, 2011, p. 4, Global Health and Aging.
4. Forissier, Thomas, and Katrina Firlik. Estimated Annual Pharmaceutical Revenue Loss Due to Medication Non-Adherence. Capgemini Group, 2012, p. 7, Estimated Annual Pharmaceutical Revenue Loss Due to Medication Non-Adherence.
5. Brown, Marie T, and Jennifer K Bussell. “Medication adherence: WHO cares?.” Mayo Clinic proceedings vol. 86,4 (2011): 304-14. doi:10.4065/mcp.2010.0575
6. Hamine, Saee et al. “Impact of mHealth chronic disease management on treatment adherence and patient outcomes: a systematic review.” Journal of medical Internet research vol. 17,2 e52. 24 Feb. 2015, doi:10.2196/jmir.3951
7. Kronish, Ian M, and Siqin Ye. “Adherence to cardiovascular medications: lessons learned and future directions.” Progress in cardiovascular diseases vol. 55,6 (2013): 590-600. doi:10.1016/j.pcad.2013.02.001
8. Jimmy, Beena, and Jimmy Jose. “Patient medication adherence: measures in daily practice.” Oman medical journal vol. 26,3 (2011): 155-9. doi:10.5001/omj.2011.38
9. Anghel, Laura Alexandra et al. “An overview of the common methods used to measure treatment adherence.” Medicine and pharmacy reports vol. 92,2 (2019): 117-122. doi:10.15386/mpr-1201