Background: Prescription drug costs constitute a burden for many chronically ill adults and are strongly related to patients' likelihood of using less medication than prescribed. We examined the extent to which patients' trust in their physicians may moderate the impact of economic constraints and other risk factors for cost-related adherence problems.
Methods: A total of 912 patients with diabetes recruited from 5 Veterans Affairs health systems completed a detailed cross-sectional survey. Patients reported their level of physician trust using a standard scale and were stratified into high-trust (n = 557) and low-trust (n = 355) groups. We fit multivariate logistic regression models with terms characterizing the interactions between physician trust and (1) patients' out-of-pocket medication costs and (2) patients' income, as well as other possible risk factors for cost-related underuse.
Results: Patients with higher out-of-pocket costs were more likely to forgo medications because of cost pressures when physician trust levels were low. Having a low income was only associated with cost-related adherence problems in the context of low physician trust. Patients who reported medication underuse for reasons other than cost were 4 times as likely as other patients to also report cost-related underuse, and those with significant depressive symptoms had more than twice the risk of cost-related underuse compared with those without depression (both P<.05).
Conclusions: These findings suggest that a trusting physician relationship may moderate the impact of cost pressures on patients' medication adherence. More generally, addressing noncost barriers to adherence may reduce rates of cost-related medication underuse.