Taking a broader perspective on medication adherence : the importance of system factors

As behavior is influenced by the system in which the patient lives, it is crucial to investigate the role of system factors in explaining adherence. To-date system level factors have received limited attention as potential predictors of medication adherence. As a consequence, the magnitude of the effect of different system factors on adherence is not known, a clear gap in the growing adherence literature. A framework which can be used in explaining the influence of system factors on behavior is an ecological model. In an ecological model 3 levels of influence on patient behavior are identified: 1) the micro level (relationships with healthcare professionals, social support) 2) the meso level (healthcare organization) and 3) the macro level (healthcare system and policy).
The overall purpose of this dissertation was to explore the role of system factors in chronic illness management, focusing on medication adherence. Five articles present the results of this work.
First, a systematic review was conducted of quantitative studies addressing factors at the different levels of the healthcare system that are associated with medication adherence in individuals with HIV and transplant (Tx) recipients. A total of 64 studies were identified. The 2 factors that were most consistently related to adherence were trust in the healthcare provider and access to medications. Across the factors examined study findings about their relationships to adherence varied. One explanation for this variability may be the wide variability in the methodological approaches utilized in studies.
The 2nd manuscript provides an overview of commonly used statistical measures for expressing the strength of the relationships between variables such as system factors and adherence. Formulas utilized to directly calculate common effect sizes from summary data reported in studies and examples of methods utilized to indirectly estimate the effect size from summary statistics are presented.
Third, a study was conducted to describe the strategies cardiovascular health professionals utilize to assess patients' medication adherence and to enhance adherence. In this study, a questionnaire was distributed to all attendants of a conference in Switzerland (March 2010). A total of 137 professionals were included. Questioning patients about NA during follow-up visits was the method used most frequently to assess adherence. Providing reading materials was the strategy used most frequently to enhance patient medication adherence.
The 4th study examined adherence assessment strategies and the interventions healthcare professionals report using to improve adherence in Tx patients. Furthermore this study examined the professionals' perceptions about the effectiveness the interventions they utilize. Data were collected at a Tx nurses symposium in Germany (June 2010). Eighty-six participants are included in this study. The most frequently used assessment strategy was questioning patients about NA during follow-up. Training patients to self-administer medications and providing printed adherence information were the most frequent interventions (79%). The intervention perceived as most effective by the professionals was medication self-administration training.
The final study describes the development, the content validity testing and the inter-rater reliability testing of the Chronic Illness Management Implementation - Building Research Initiative Group: Chronic Illness Management and Adherence in Transplantation (CIMI-BRIGHT) instrument. The development of the CIMI-BRIGHT instrument was based on the conceptual framework of WHO's Innovative Care for Chronic Conditions framework, as well as the clinical expertise of the research team. Initial psychometric testing (content validity and inter-rating reliability) were conducted. Content validity was evaluated by 7 experts in chronic illness management. They rated the relevance of each item in terms of the construct 'chronic illness management' on a 4-point Likert scale (1=not relevant, 4=highly relevant). Content validity indexes were calculated for each item and the survey as a whole. Of the 51 items, 42 were had good content validity. To evaluate inter-rater reliability, a pilot study was conducted in 2 Tx programs. The percentage agreement in the 2 centers for the total instrument scores was 84.6% and 74.8%.
Synthesizing the findings of the studies yields the following 3 key results which contribute to the current state of knowledge. First, there remains a significant knowledge deficit in view of the influence of healthcare system factors on medication adherence calling for further research investment. Second, nurses' practice patterns in view of adherence-related interventions call for a change in curricula. Finally, The CIMI-BRIGHT instrument is the first and only tool developed to systematically assess the level of chronic illness management in Tx centers and thus provides a building block for further observational and intervention research in transplantation.