Patient traits and adherence

Although one might expect that older adults would have lower levels of medication adherence than younger adults, some studies have shown that older adults may have higher levels of adherence, perhaps because they are not as busy with other activities as are younger persons,¹⁰ or because they are more aware of the potential impact that medications may have on their health.⁶ However, in a study by Carney et al, depression was significantly associated with worse medication adherence in elders.¹¹

In some studies, age has not been directly related to adherence, although poorer cognitive function has. Since increasing age places elders at greater risk for deficits in memory or general cognitive function, the apparent relation between adherence and age may be mediated by cognition rather than age itself. Other patient characteristics, such as socioeconomic status, may be related to adherence.¹²

Patient beliefs and adherence

The Health Belief Model¹³ has been a stimulus for numerous studies of medication adherence. Starting with the idea that patients' beliefs about medications will impact how they take these medications, the model predicts that patients' beliefs about their conditions and the conditions' likely outcomes with and without treatment will affect adherence.

In a study of patients at a memory disorders clinic based partly on this model, a complex pattern of connections was found among patient beliefs and adherence as reported by caregivers.⁶ Numerous variables were assessed, including cognitive status as an index of dementia severity, number of medications, total number of medication doses per day as an index of regimen complexity, and whether the patient depended on a caregiver or him-or herself to remember to take the medication. Patients' beliefs about the seriousness of their condition were significant predictors of their rating of its likely outcome without treatment; this rating was, in turn, related to adherence. In this study, older age was related to better adherence, while the presence of side effects was related to lower levels of adherence.

Risk factors for nonadherence

Table 1 Key risk factors for nonadherence

Given the complexity of medication adherence and the difficulties that practicing clinicians face in assessing and addressing it, clinicians should be advised to focus on significant factors in nonadherence (table 1). In our ongoing study of medication nonadherence in patients with a mean age of 82.3 years, analysis of preliminary data reveal two distinct patterns of adherence.¹⁴ A majority (ie, 80% to 90%) of patients have high levels of medication adherence as determined by electronic monitoring. These patients still function at independent levels in activities of daily living, and their memory impairments are mild. They often live with a spouse or another caregiver.

A smaller, but distinct, second group (10% to 20%) of patients has been identified as having low levels of adherence. They may still live independently, but show clear evidence of memory impairment. They typically live alone and report that they rely on themselves and not a mechanical aid (eg, pillbox) to remember to take their medication.

Table 2 Adherence assessment in older patients

These observations are similar to those of other adherence studies of the elderly.^15,16 A European study with a population-based random sample of persons age 75,¹⁵ for example, showed that evidence of cognitive impairment (MMSE score less than 24) increased the likelihood of nonadherence nine times, and that elders living alone were twice as likely to have medication errors. This study did not explore the effect of the presence of a caregiver, but it showed that the use of a compliance aid (eg, pillbox) increased adherence by nearly 4.5 times. The study showed that many patients had low levels of knowledge about medications and the purpose for which they had been prescribed. In fact, 40% of patients did not know the purpose of the medication, 79% did not know the consequences of not taking medication, and 95% were not aware of the possibility of a toxic drug reaction.

Communication patterns, and most likely, the physician-patient relationship they reflect, affect medication adherence.¹¹ Stewart et al¹⁷ argue that three physician behaviors may be critical for medication adherence:

1) Provide a full explanation of the reason for prescribing the medication and provide the expected outcome. Tell the patient WHY you are prescribing this drug and what you expect it will do.

2) Emphasize the shared responsibility of the patient and physician in health outcomes. Tell the patient that you have done what would be expected given these symptoms or this condition, and what you expect him or her to do as well.

3) Explore factors in the patient's life relevant to obtaining and using the medication as scheduled. Ask the patient if there are any reasons why he or she may not be able to do as you have instructed.

Although time consuming, developing a relationship with individual patients and providing them with this type of information may aid in improving adherence.

Other factors associated with medication nonadherence in the older adult include:

• Regimen complexity. Consider simplifying regimen complexity (eg, reducing the number of times medications are taken daily) to improve adherence.¹²
• Acuity. How well a patient understands the medical condition for which he or she is being treated has an impact on adherence, with decreasing adherence over time in chronic, largely asymptomatic conditions, such as hypertension¹⁸ and dyslipidemias.¹⁶
• Economics. The importance of economic factors should not be neglected. Patients who have difficulty paying for medication report skipping medications a majority of the time.^19,20

Assessing adherence

Table 3 Assessing functional ability to adhere

One research finding on the assessment of patient medication adherence is consistent: patient self-report of adherence is unreliable. Therefore, clinicians must be careful to use supplementary information when assessing patients' medication adherence. If self-report is used, MacLaughlin et al²¹ argue that open-ended questions are more likely to elicit accurate information than specific questions with yes or no answers. Rather than asking the patient "Are you taking your medications as prescribed?" it may be preferable to say, "Tell me how you take your medications," or to ask the patient to demonstrate how he or she takes their medications with a pillbox.

The clinician may ask the patient about side effects as a means of assessing adherence, since the presence of side effects may reduce patients' adherence. The clinician can ask open-ended questions, or ask specific questions about common side effects, opening the conversation to possible reasons why a patient does not take a specific medication.

Several systematic methods of assessing a patient's functional ability to adhere are listed in tables 2 and 3.^22-24 In general, these methods provide standardized assessments of medication adherence-related behaviors, such as understanding directions on a prescription label and identifying correct times to take doses.

Electronic medication adherence monitors, although most often used in research contexts, are potentially useful in clinical settings. These monitors record the time and date at which doses of medication are taken. Information can be recorded centrally by telephone or at each visit.

Improving adherence

Table 4 Strategies for improving medication adherence in older patients

Several extensive reviews evaluate the effectiveness of methods to improve medication adherence.^25-27 Methods for improving patient adherence are listed in table 4. In general, studies of interventions to improve patient adherence to medication regimens have shown small, but statistically significant, effects. Small changes in adherence may be difficult for clinicians to detect and interventions that produce them may thus appear ineffective.

Further, studies have typically included participants with a wide range of levels of adherence. Since studies have shown that older patients may have high levels of adherence, the effect of an intervention on groups of persons with high and low levels of adherence may be watered down in these studies.

Research studies have shown different rates of adherence in patients with different demographic characteristics (eg, nonwhite¹⁶ ), in different diseases, and with different medications. Ultimately, it may be necessary to develop individually tailored interventions that consider patient, disease, and treatment characteristics.

Use of technology-based interventions may be a useful strategy for dealing with poor medication adherence.²⁸ For example, while tailored information interventions (interventions that target patient adherence by providing information tailored to patients' interests or needs) are known to improve adherence, preparation of tailored medication information for each individual may be excessively time-consuming. Creation of educational materials can be automated through a computer-based application, making the preparation and dissemination of individually-tailored materials part of clinical office practice.²⁹ Other automated interventions (eg, computer-based telephone reminding), have also been shown to improve adherence.³⁰

Conclusion

Although critically important, medication adherence in older adults is a poorly understood phenomenon with multiple determining factors. Research on interventions to improve adherence has shown modest, but statistically significant, effects. However, results of existing studies make it difficult to determine the most important factors for improving adherence.

It is not clear the extent to which observed effects on adherence are related to already high levels of adherence in some patients. Future efforts to improve adherence may require individually-targeted interventions that consider important patient and disease characteristics. Technological devices may aid in this time-and labor-intensive effort.

Acknowledgments: Preparation of this article was supported by grant K23 AG19745 from the National Institute on Aging to Dr. Ownby. The author also acknowledges the contribution of an anonymous reviewer some of whose comments and suggestions are incorporated in this article.

Dr. Ownby is professor, department of psychiatry and behavioral sciences, University of Miami Miller School of Medicine, Miami, FL.

Disclosures: Dr. Ownby has no actual or apparent conflict of interest with the subject of this article. He has no financial or other material interest conflict with the companies that manufacture the electronic medication adherence monitors described in this article.

References

1. Kohn LT, Corrigan JM, Donaldson MS. To err is human: Building a safer health system. Washington, DC: National Academy Press; 2000.

2. McDonald HP, Garg AX, Haynes RB. Interventions to enhance patient adherence to medication prescriptions; scientific review. JAMA 2002; 288(22):2868–79.

3. Gurwitz JH, Field TS, Harrold LR, et al. Incidence and preventability of adverse drug events among older persons in the ambulatory setting. JAMA 2003; 289(9):1107–16.

4. Finucane ML, Slovic P, Hibbard JH, Peters E, Mertz DK, McGregor DG. Aging and decision-making competence: An analysis of comprehension and consistency skills in older versus younger adults considering health plan options. J Behav Decis Making 2002; 15(2):141-64.

5. Bultman DC, Svarstad BL. Effects of physician communication style on client medication beliefs and adherence with antidepressant treatment. Patient Educ Couns 2000; 40(2):173-85.

6. Ownby RL, Hertzog C, Crocco E, Duara R. Factors related to medication adherence in memory disorder clinic patients. Aging and Mental Health; in press.

7. Ownby RL. Relation of cognitive status and health literacy to medication adherence. Paper presented at the annual meeting of the American Association for Geriatric Psychiatry, San Diego, March 2005. Available at http://www.patcai.org/pubs.htm. Accessed January 12, 2006.

8. Parker RM, Baker DW, Williams MV, Nurss JR. The test of functional health literacy in adults: A new instrument for measuring patients' literacy skills. J Gen Intern Med 1995; 10(10):537–41.

9. Rosen WG, Mohs RC, Davis KL. A new rating scale for Alzheimer's disease. Am J Psychiatry 1984; 141(11):1356–64.

10. Park DC, Hertzog C, Leventhal H, et al. Medication adherence in rheumatoid arthritis patients: Older is wiser. J Am Geriatr Soc 1999; 47(2):172–83.

11. Carney RM, Freedland KE, Eisen SA, Rich MW, Jaffe AS. Major depression and medication adherence in elderly patients with coronary artery disease. Health Psychol 1995; 14(1):88–90.

12. Balkrishnan R. Predictors of medication adherence in the elderly. Clin Ther 1998; 20(4):764–71.

13. Janz NK, Becker MH. The Health Belief Model: A decade later. Health Educ Q 1984 (Spring); 11(1):1–47.

14. Ownby RL. Patterns of medication adherence in memory disorder clinic patients. Paper accepted for presentation at the annual meeting of the American Association for Geriatric Psychiatry, San Juan, Puerto Rico. Available at http://www.patcai.org/pubs.htm. Accessed January 12, 2006.

15. Barat I, Andreasen F, Damsgaard EM. Drug therapy in the elderly: What doctors believe and patients actually do. Br J Clin Pharmacol 2001; 51(6):615–22.

16. Benner JS, Glynn RJ, Mogun H, Neumann PJ, Weinstein MC, Avorn J. Long-term persistence in use of statin therapy in elderly patients. JAMA 2002; 288(4):455-61.

17. Stewart M, Meredith L, Brown JB, Galajda J. Influence of older patient-physician communication on health and health-related outcomes. Clin Geriatr Med 2000; 16(1):25–36.

18. Chapman RH, Benner JS, Petrilla AA, et al. Predictors of adherence with antihypertensive and lipid-lowering therapy. Arch Intern Med 2005; 165(10):1147–52.

19. Piette JD, Heisler M. Problems due to medication costs among VA and non-VA patients with chronic illnesses. Am J Manag Care 2004; 10(11 part 2):861–8.

20. Mojtabai R, Olfson M. Medication costs, adherence, and health outcomes among Medicare beneficiaries. Health AFF (Millwood) 2003; 22(4):220–9.

21. MacLaughlin E, Raehl C, Treadway A, Sterling T, Zoller D, Bond C. Assessing medication adherence in the elderly: Which tools to use in clinical practice? Drugs Aging 2005; 22(3):231–55.

22. Raehl CL, Bond CA, Woods T, Patry RA, Sleeper RB. Individualized drug use assessment in the elderly. Phamacotherapy 2002; 22(10):1239–48.

23. Carlson MC, Fried LP, Xue QL, Tekwe C, Brandt J. Validation of the Hopkins Medication Schedule to identify difficulties in taking medications. J Gerontol A Biol Sci Med Sci 2005; 60(2):217–23.

24. Edelberg HK, Shallenberger E, Hausdorff JM, Wei JY. One-year follow-up of medication management capacity in highly functioning older adults. J Gerontol A Biol Sci Med Sci 2000; 55(10):M550–3.

25. Peterson AM, Takiya L, Finley R. Meta-analysis of trials of interventions to improve medication adherence. Am J Health Syst Pharm 2003; 60(7):657-65.

26. McDonald H, Garg AX, Haynes RB. Interventions to enhance patient adherence to medications prescriptions: scientific review. JAMA 2002; 288(22):2868–79.

27. Haynes RB, McDonald H, Garg AX, Montague P. Interventions for helping patients to follow prescriptions for medications. Cochrane Database Syst Rev 2002; (2):CD000011. Review.

28. Durso SC. Technological advances for improving medication adherence in the elderly. Ann Long-Term Care 2001; 9(4):43-8.

29. Ownby RL. Development of an interactive tailored information application to improve patient medication adherence. Proceedings of the American Medical Informatics Association 2005. [CD-ROM]. 1069.

30. Revere D, Dunbar PJ. Review of computer-generated outpatient health behavior interventions: Clinical encounters "in absentia." J Am Med Inform Assoc 2001; 8(1):62–79. Review.