Patients who forgo medications for both diabetes and chronic pain appear to be influenced primarily by economic pressures, whereas patients who cut back selectively on their diabetes treatments are influenced by their mood and medication beliefs. Our findings point toward more targeted strategies to assist diabetic patients who experience CRN.

Prescription drug spending in 2007 was >750 USD per capita in the U.S., of which patients must pay a growing share through medication copayments. Nine of 10 older adults use prescription medications, and those with Medicare Part D take five prescriptions per month on average. Even among low-income patients, most take their medications despite copayments; however, one-fifth or more of all patients may cut back because of cost concerns. Cost-related nonadherence to medications (CRN) has been associated with increased rates of serious adverse events, emergency department visits, hospitalizations, and poorer health.

Empirical studies have implicated financial, attitudinal, mood, and provider influences in CRN, although their relative effects are not well understood. Most of the variance in patients’ reports of CRN remains unexplained by financial measures. Although economic pressures drive these decisions, noncost factors appear to modify the effect of medication cost at a given level of ability to pay.

Most survey-based studies of CRN have used a single global question to ascertain adherence and, therefore, could not discern whether patients cut back uniformly across their medications or selectively. Studies using administrative data indicate that patients vary in their adherence across medications, but these studies could not explore fully the influences of factors such as patients’ mood and medication-related beliefs.

Building on our theoretical model of factors that influence patients’ elasticity of demand for prescription drugs, in the present study we explored further how cost and noncost factors influence patients’ adherence to prescription medications for two chronic conditions: type 2 diabetes and chronic pain. We hypothesized that although some patients would cut back on medications for both conditions, others would cut back selectively, and sought to understand the factors associated with these behaviors.

These analyses are important for clinical care because most efforts to address CRN have targeted patients’ ability to pay exclusively, for example, through government assistance (e.g., Medicare Part D), pharmaceutical industry programs, and prescribing of less expensive therapeutic alternatives. Physicians are now called upon to incorporate discussions of medication cost pressures into their routine patient interactions. Because insufficient time may be the greatest barrier to such provider-initiated discussions, it is essential that we distinguish patients for whom ability to pay, as opposed to other factors, constitutes the dominant challenge to adherence.