Background
Medication nonadherence is a common problem among the elderly.
Objective
To conduct a systematic review of the published literature describing potential non-financial barriers to medication adherence among the elderly.
Methods
The PubMed and PsychINFO databases were searched for articles published in English between January 1998 and January 2010 that described “predictors,” “facilitators,” or “determinants” of medication adherence and those articles that examined the “relationship” between a specific barrier and adherence for elderly patients (ie, age ≥ 65 years) in the United States (U.S.). A manual search of the reference lists of identified articles and the authors’ files and recent review articles was conducted. The search included articles that (1) reviewed specific barriers to medication adherence and did not solely describe nonmodifiable predictors of adherence (eg, demographics, marital status); (2) were not interventions designed to address adherence; (3) defined adherence or compliance and specified its method of measurement; (4) involved U.S. participants only. Non-systematic reviews were excluded, as were studies that focused specifically on people who were homeless or substance abusers, or patients with psychotic disorders, tuberculosis, or Human Immunodeficiency Virus (HIV), because of the unique circumstances that surround medication adherence for each of these populations.
Results
Nine studies met inclusion criteria for this review. Four studies used pharmacy records/claims data to assess adherence, 2 studies used pill count/electronic monitoring, and 3 studies used other methods to assess adherence. Substantial heterogeneity existed among the populations studied as well as among the measures of adherence, barriers addressed, and significant findings. Some potential barriers (ie, factors associated with nonadherence) were identified from the studies, including patient-related factors such as disease-related knowledge, health literacy, and cognitive function, drug-related factors such as adverse effects and polypharmacy, and other factors including the patient-provider relationship and various logistical barriers to obtaining medications. None of the reviewed studies examined primary nonadherence or nonpersistence.
Conclusion
Medication nonadherence in the elderly is not well described in the literature, despite being a major cause of morbidity, and thus it is difficult to draw a systematic conclusion on potential barriers based on the current literature. Future research should focus on standardizing medication adherence measurements among the elderly in order to gain a better understanding of this important issue.
This analysis provides evidence that depression is associated with poor adherence to medication across a range of chronic diseases, and we find a new potential effect of adherence measurement type on this relationship. Although this study cannot assess causality, it supports the importance that must be placed on depression in studies that assess adherence and attempt to improve it.
Dual process models of addiction suggest that the influence of alcohol-related cognition might be dependent on the level of executive functioning. This study investigated if the interaction between implicit and explicit alcohol-related cognitions and working memory capacity predicted alcohol use after one month in at-risk youth. Implicit and explicit alcohol-related cognitions were assessed in 88 Dutch at-risk adolescents ranging in age from 14 to 20 (51 males) with an adapted version of the Implicit Association Test (IAT) and an expectancy questionnaire. Working memory capacity was assessed using the computer-based version of the Self-Ordered Pointing Task (SOPT). Alcohol use and alcohol-related problems were measured at baseline and after one month with self-report questionnaires. The hierarchical regression analysis showed that both the interaction between implicit positive-arousal cognitions and working memory capacity and the interaction between explicit positive-arousal cognitions and working memory capacity predicted unique variance in alcohol use after one month. Implicit positive-arousal cognitions predicted alcohol use after one month more strongly in students with lower levels of working memory capacity, whereas explicit positive-arousal cognitions predicted one-month follow-up alcohol use more strongly in students with higher levels of working memory capacity. This could imply that different intervention methods could be effective for different subgroups of at-risk youth.
Some theories suggest that spontaneously activated, drug-related associations in memory may have a “freer reign” in predicting drug use among individuals with lower working memory capacity. This study evaluated this hypothesis among 145 at-risk youth attending continuation high schools (CHS). This is the first study to evaluate this type of dual-process interaction in the prediction of drug use among a sample of at-risk adolescents. The CHS students completed assessments of drug-related memory associations, working memory capacity, and drug use. Control variables included age, gender, ethnicity, and acculturation. Robust multiple regression using least trimmed squares estimation indicated that there was a significant linear by linear interaction between working memory capacity as assessed with the self-ordered pointing task (SOPT) and drug-related associations (assessed with verb generation and cue-behavior association tasks) in the prediction of alcohol and cigarette use. Consistent with dual-process cognitive theories, drug-related associations in memory predicted drug use more strongly in students with lower levels of working memory capacity. These findings add to the literature implicating the influence of dual cognitive processes in adolescent risk behaviors.
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