Medication adherence is defined as the "active, voluntary, and collaborative engagement of the patient in a mutually acceptable course of behavior to produce a therapeutic result."^1,2 It is defined as a patient's medication-taking behavior and the degree to which a patient follows the prescription regimen that was mutually established with his or her health care provider.³ While medication adherence can vary from total noncompliance to perfect adherence, prior studies suggest that overall patient adherence to medications is about 50%.⁴ Current American College of Cardiology (ACC)/American Heart Association (AHA) clinical guidelines emphasize the importance of medication adherence, and medication non-adherence is germane to any cardiovascular or clinical condition for which treatment involves medications.^5,6

Poor medication adherence is associated with adverse health outcomes, reduced quality of life, and increases in health care spending.^7-9 As medication non-adherence is common and adherence to medication regimens is important to ensure the benefits of prescribed therapies, the assessment of medication adherence should be incorporated into routine clinical care. One approach would be to assess medication adherence at every office visit.

So what would this look like? Currently, patients routinely get their temperature, respiratory rate, blood pressure, and heart rate assessed as part of their visit with a clinician. During the assessment of vital signs, patients could be asked a question that addresses whether they are having any issues taking their current medications. There are a variety of validated questions that address the issue of medication non-adherence. For example, a health care provider can ask, "I know it must be difficult to take all your medications regularly. How often do you miss taking them?" Another approach is to inquire about medications that the patient is taking by asking, "How often do you not take medication X?"¹⁰ The patient's response to the question or questions may be specific for adherence problems and indicate the need for further discussion about potential medication related issues during the clinic visit or thereafter. When medication adherence is identified as a problem, the patient and provider can explore potential patient, provider, or system barriers contributing to non-adherence. The following are potential steps for assessing medication adherence in a routine clinic visit:

1. Patient checks into office visit.
2. Front office staff gives patient a questionnaire that asks about adherence issues.
3. A nurse takes the patient into the exam room obtains vital signs. Nurse reviews the questionnaire, or, if patient is unable to fill out questionnaire, administers questionnaire orally.
4. If the patient's responses to the questionnaire indicate medication adherence issues, the nurse can address these issues and then flag for the provider to further address during the visit and/or refer the patient to a pharmacist if available.

The act of asking questions about adherence highlights the importance of medications and emphasizes the need to take them regularly to the patient. A review by Garfield et al. identified 58 self-report measures, some of which were tailored to specific medications, patient populations, and chronic diseases.¹¹ Self-report methods for assessing adherence have been validated for a variety of clinical settings and have been found to produce comparable results to electronic monitoring devices.¹² Several studies have found that patient disclosure of non-adherence in interviews and questionnaires is an accurate representation of their medication taking behavior.^13-14 While self-report measures are simple, easy to use, and inexpensive, they possess inherent limitations, including recall bias, social desirability bias, and lack of continuous data.¹⁵ Despite these limitations, the practical nature and simplicity of self-reported adherence behavior makes them one of the easier methods currently available to assess adherence in routine clinical practice.

Other indirect methods to assess adherence include pill counts, electronic monitors, and pharmacy refill data; of these methods, utilizing pharmacy refill data is the most practical for routine clinical use. Pharmacy refill-based adherence measures compare the amount of medication obtained by the patient to the amount of medication prescribed by their provider over a specific interval. The medication possession ratio and the proportion of days covered are two commonly used refill-based adherence measures. The two measures differ in that the upper limit for proportion of days covered is 1, representing perfect adherence, whereas medication possession ratio accounts for the scenario of a patient overstocking prescriptions and allows for an adherence proportion greater than 1.^16-20 Additionally, if pharmacy refill data is available, observing for gaps between medication refills can be another simple method to assess adherence. When these data are accessible, an extra step can be added to the assessment of adherence during an office visit in which a nurse assesses medication adherence by looking for breaks between refills for each of the patient's medications.

Adherence measurement based on pharmacy refill data has been validated and found to produce similar results to those attained from electronic monitors.²¹ Advantages of pharmacy refill measures are that they are non-invasive, inexpensive, and provide objective continuous, long-term data on medication taking behavior.^3,16 However, this method of assessing adherence requires access to complete medication refill data, which may not be available outside of closed pharmacy systems. As the prevalence of electronic medical records and e-prescribing increase, there may be opportunities to use pharmacy refill data outside of integrated health care systems. Additionally, examining prescription refill data establishes that the patient obtained the medication but does not provide evidence that the medication was ingested or reveal the timing of doses taken.^16,18,19

There is increasing interest in the use of electronic bottle monitors and mobile applications to improve medication adherence. While electronic bottle monitors (e.g., medication event monitoring system caps) have been used in clinical trials and other research settings, there is a growing commercial interest to expand the use of these devices more broadly. For example, there are electronic bottle monitors that will remind patients that they are due to take their medications by changing colors. Similarly, there are mobile applications for cellphones that will alert patients to take their next dose of medications. Both electronic monitors and mobile applications can remind and provide feedback to patients, but these technologies do not provide information about whether the pill was actually taken. Further, there may be challenges to use of these technologies when patients take multiple medications as well as concern about reminder fatigue. While cost is an additional limitation to the widespread use of these devices, the larger challenge is integrating the information derived from these electronic devices into current electronic health records to provide actionable data for health care providers and their teams. This data integration will be one of the keys towards more widespread adoption of these devices and applications.

Until then, use of patient self-report and pharmacy refill adherence measures may be the most practical. An ideal approach would be to combine these methods in the assessment of medication adherence in routine clinical practice. Several studies suggest that the use of multiple assessments increases the accuracy and validity of medication adherence estimates.^15,22,23 Leveraging both approaches is likely to further illuminate patient barriers to adherence. However, it should be noted that there are certain situations in which one method may be superior to the other. For example, if a patient has cognitive impairment or is unable to perform a self-report assessment, pharmacy refill would be a better method of measuring adherence. In contrast, self-report may be a preferred method if a medication is only taken over a short period of time (e.g., antibiotics for treatment of an infection) or if the dose is not stable during the time interval being examined (e.g., diuretic).²⁴

Including the assessment of medication adherence as part of the vital signs during all clinical visits highlights its importance to patients and providers alike. If poor medication adherence is identified, it can be addressed during the office visit as there may be potential patient, provider, and health care system reasons for poor medication adherence. These reasons could include one or more of the following: patients' forgetfulness and lack of understanding of the benefits and side effects of medication, complexity of the regimen prescribed by physician, cost of medications, and/or quality of the patient-provider relationship. In every clinical encounter, a health care provider should review the results of the medication adherence assessments as adherence can vary over time and may be related to interim events that have occurred between office visits. The focus on medications also allows health care providers the opportunity to review the medication regimen, explain the purpose of each medication to the patient, and eliminate medications that are no longer needed. When medication adherence is identified as an issue either through a self-report questionnaire or review of pharmacy refill data, the patient and clinician can explore the factors contributing to non-adherence and potential solutions to overcome these adherence barriers.

Adopting assessment of adherence as a vital sign will allow both patients and providers to review prescription regimen and establish treatment goals, both of which are key to successful adherence. Further, as the reasons for suboptimal adherence are often multi-faceted, this approach allows health care professionals the opportunity to address patient-specific barriers to adherence. Given that, on average, patients have four outpatient office visits per year, especially those with chronic medical conditions, the assessment of medication adherence as part of the outpatient visit could be the beginning of a broader effort to address the issue of medication non-adherence.²⁵ Although including assessment of medication adherence into routine clinical practice involves more steps and adds additional time to physician office visits, improving medication adherence will allow patients to reap the benefits of prescribed medications and improve health outcomes.

References

1. Delamater AM. Improving patient adherence. Clin Diabetes 2006;24:71-7.
2. Meichenbaum D, Turk DC. Facilitating Treatment Adherence: A Practitioner's Guidebook. New York, NY: Plenum Press; 1987.
3. Osterberg L, Blaschke T. Adherence to medication. N Engl J Med 2005;353:487-97.
4. Nieuwlaat R, Wilczynski N, Navarro T, et al. Interventions for enhancing medication adherence. Cochrane Database Syst Rev 2014;11:CD000011.
5. Nallamothu BK, Tommaso CL, Anderson HV, et al. ACC/AHA/SCAI/AMA-Convened PCPI/NCQA 2013 performance measures for adults undergoing percutaneous coronary intervention: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures, the Society for Cardiovascular Angiography and Interventions, the American Medical Association-convened Physician Consortium for Performance Improvement, and the National Committee for Quality Assurance. J Am Coll Cardiol 2014;63:722-45.
6. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;64:e139-228.
7. Haynes RB, Ackloo E, Sahota N, McDonald HP, Yao X. Interventions for enhancing medication adherence. Cochrane Database Syst Rev 2008;2:CD000011.
8. Golay A. Pharmacoeconomic aspects of poor adherence: can better adherence reduce healthcare costs? J Med Econ 2011;14:594-608.
9. Hsu KL, Fink JC, Ginsberg JS, et al. Self-reported medication adherence and adverse patient safety events in CKD. Am J Kidney Dis 2015;66;621-9.
10. Brown MT, Bussell JK. Medication adherence: WHO cares? Mayo Clin Proc 2011;86:304-14.
11. Garfield S, Clifford S, Eliasson L, Barber N, Willson A. Suitability of measures of self-reported medication adherence for routine clinical use: a systematic review. BMC Med Res Methodol 2011;11:149.
12. Shi L, Liu J, Koleva Y, Fonseca V, Kalsekar A, Pawaskar M. Concordance of adherence measurement using self-reported adherence questionnaires and medication monitoring devices. Pharmacoeconomics 2010;28:1097-107.
13. Choo PW, Rand CS, Inui TS, et al. Validation of patient reports, automated pharmacy records, and pill counts with electronic monitoring of adherence to antihypertensive therapy. Med Care 1999;37:846-57.
14. Wagner JH, Justice AC, Chesney M, et al. Patient- and provider-reported adherence: toward a clinically useful approach to measuring antiretroviral adherence. J Clin Epidemiol 2001;54:S91-8.
15. Lehmann A, Aslani P, Ahmed R, et al. Assessing medication adherence: options to consider. Int J Clin Pharm 2014;36:55-69.
16. Hess LM, Raebel MA, Connor DA, Malone DC. Measurement of adherence in pharmacy administrative databases: a proposal for standard definitions and preferred measures. Ann Pharmacother 2006;40:1280-8.
17. Halpern MT, Khan ZM, Schmier JK, et al. Recommendations for evaluating compliance and persistence with hypertension therapy using retrospective data. Hypertension 2006;47:1039-48.
18. Steiner JF, Pochazka AV. The assessment of refill compliance using pharmacy records: methods, validity, and applications. J Clin Epidemiol 1997;50:105-16.
19. Krueger KP, Berger BA, Felkey B. Medication adherence and persistence: a comprehensive review. Adv Ther 2005;22:313-56.
20. Steiner JF, Koepsell TD, Fihn SD, Inui TS. A general method of compliance assessment using centralized pharmacy records: description and validation. Med Care 1988;26:814-23.
21. Hansen RA, Kim MM, Song L, Tu W, Wu J, Murray MD. Comparison of methods to assess medication adherence and classify nonadherence. Ann Pharmacother 2009;43:413-22.
22. Liu H, Golin CE, Miller LG, et al. A comparison study of multiple measures of adherence to HIV protease inhibitors. Ann Intern Med 2001;134:968-77.
23. Turner BJ, Hecht FM. Improving on a coin toss to predict patient adherence to medications. Ann Intern Med 2001;134:1004-6.
24. Vik SA, Maxwell CJ, Hogan DB. Measurement, correlates, and health outcomes of medication adherence among seniors. Ann Pharmacother 2004;38:303-12.
25. Schappert SM, Rechtsteiner EA. Ambulatory medical care utilization estimates for 2006. Natl Health Stat Report 2008;8:1-29.

Keywords: Ambulatory Care, American Heart Association, Anti-Bacterial Agents, Blood Pressure, Chronic Disease, Cognition Disorders, Delivery of Health Care, Integrated, Diuretics, Electronic Health Records, Electronic Prescribing, Heart Rate, Medication Adherence, Mobile Applications, Office Visits, Outpatients, Pharmaceutical Services, Pharmacies, Pharmacists, Physicians, Physicians' Offices, Prevalence, Quality of Life, Respiratory Rate, Self Report, Social Desirability, Primary Prevention

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