Review articleA Systematic Review of Barriers to Medication Adherence in the Elderly: Looking Beyond Cost and Regimen Complexity
Introduction
Medications are frequently used in the elderly to improve quality of life, extend life-expectancy, and cure or mitigate disease. It is clear, however, that the elderly often fail to adhere to prescribed medications, which can lead to unwelcome clinical and economic consequences.1, 2, 3
For a variety of reasons, patients do not adhere to their prescribed medication regimens. One conceptual model of barriers to adherence describes patient, prescriber, and health care system factors.4 Others have developed more detailed conceptual models specific to the elderly.2, 3, 5 Each model highlights the fact that the medication use process is affected by many factors in older adults, including drug- and patient-related issues, such as patient representations of their illness, cognitive function, medication side effects, and patient-prescriber relationships. Furthermore, because older adults often suffer from multiple comorbid conditions and thus use more medications than their younger counterparts, medication nonadherence can have drastic deleterious health effects on the elderly.2 Therefore, finding potential areas for interventions to help improve this process should be a top priority of health care providers.
Most modifiable barriers that hinder an older adult from adequately adhering to prescribed medications are not clearly described in the literature, with the exception of cost, which is well described.6, 7, 8, 9, 10, 11 Prior reviews of medication adherence in the elderly cite inconsistencies across studies and draw few solid conclusions; in addition, these reviews contain many dated studies, and some include patients <65 years of age.1, 2, 12
Given this background and the objective to identify barriers to adherence specific to patients in the United States, a systematic review of the published literature was conducted that described potential nonfinancial barriers to medication adherence among patients ≥65 years.
Section snippets
Data Sources
The PubMed and PsychINFO databases were searched, covering the period from January 1998 to January 2010, limiting the field to English-language publications, and omitting the publication types of “letters,” “editorials,” and “comments.” The year 1998 was used as the baseline year for the search because a previous review of medication adherence in the elderly was published using the years 1962 to 1997.1 The search strategy utilized both MeSH and non-MeSH terms, as outlined in Figure 1.
Eligibility Criteria
The search
Results
Nine articles that met inclusion criteria in this systematic review were included. Details from the studies in this review, including study sample, disease studied, method of assessing adherence, barriers discussed, and findings, are summarized in Table I. Four studies used pharmacy records or claims data to assess adherence, 2 studies used pill count or electronic monitoring, and 3 studies used other methods to assess adherence. The 9 articles included in this review varied in their methods of
Discussion
There are no known prior systematic reviews of the nonfinancial barriers to medication adherence among the US elderly (ie, aged ≥65 years). This search found only 9 studies that met the inclusion criteria, and each one studied a different population or disease or used a different assessment of medication adherence, making a clear synthesis of the literature extremely difficult. Studies of adherence have been burdened by heterogeneity for decades,26, 27, 28 and recent literature seems to be no
Conclusions
This systematic review found a large amount of heterogeneity in the methods used to define, assess, and measure medication adherence in the elderly; thus, it is not possible to make systematic conclusions. However, several potentially modifiable barriers to medication adherence were identified. The current state of the literature regarding modifiable barriers to medication adherence among older adults is limited and suggests a great need for well-designed studies and a consistently measured
Acknowledgments
This study was supported by an Agency for Healthcare Research and Quality grant (T32 HS00046-14), a National Institute of Aging Grant (T32 AG021885), and Mehlman Vogel Castagnetti. Dr. Gellad is additionally supported by a VA HSR&D Career Development Award. The authors would like to thank Joseph T. Hanlon, PharmD, MS, for his assistance with earlier drafts of this manuscript.
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