Path Analysis of Psychological Factors Associated with Medication Adherence for Individuals with Chronic Diseases

The 100 million U. S. residents with hypertension or diabetes generally struggle with medication adherence (MA). On average, 65% refer to themselves as nonadherent in some way, complicating attempts to ascertain the benefits of medical care to reduce morbidity and morality. It is important, therefore, to ask why patients are not taking effective medications. In answering this question, there is some evidence that individuals dismiss the long-term benefits of better nutrition or lifestyle choices due to the asymptomatic or silent nature of chronic diseases (Takiya, Peterson, & Finley, 2004). Nonetheless, there has been limited progresss in targetting barriers based on demographic and biomedical factors, because they have not been modifiable predictors of adherence. Clinicians have been looking more to internal phenomena for motivational impetus to meet treatment demands. This community-based observational study evaluated statistical associations of three psychological constructs, time perspective (TP), health beliefs, and health locus of control beliefs on MA for 79 participants using data accessed with permission from the Clinical Trial and Outcomes Branch of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Path analysis tested the direct effect of TP on MA and the indirect of TP through mediators. Results showed that failure to complete drug regimens is a reality for over 50% of participants. The psychological pathways exhibited some influence in observed medication adherence, but required further manipulation to determine the model of direct and indirect effects between variables. Most notably, analyses did not dectect any direct effect from either future or present-hedonistic time perspective, where older age and greater internal locus of control directly predicted better drug use. Internal locus of control outperformed all other predictors- an increase by a single unit contributed to a 0.77 standard deviation change in the probability of individuals having higher MA. Among indirect effect tests, individuals\u27 internal loci of control also mediated the effect of time perspective on adhrenece. Both present-hedonistic and future outlooks operated through the mediator to boost prescription drug use. The current study provides the first categrocial data model of the strength and direction of simultaneous associations between the described psychological pathways and adherence