Date of Award

7-9-2009

Document Type

Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Josheph Agostini

Abstract

Medication decision making in older adults with multiple chronic conditions is complicated; communication between patients and physicians to establish concordant treatment goals can enhance this process. While patients' ability to make informed decisions about treatment priorities depends on their ability to understand the risks and benefits of medications and the likelihood of disease outcomes, patients' knowledge of medication-related benefits is unexplored. We examined older adults' estimation of their 10-year risk of myocardial infarction (MI) and stroke, and the degree to which they thought common medications were able to prevent these outcomes. 150 male veterans age 65 or older and taking five or more medications (including an aspirin, a statin, or an antihypertensive drug) were interviewed at VA Connecticut. Using a bar graph with bars representing 0, 10, 25, 50, 75, and 100%, participants were asked to estimate their 10-year risk of stroke and MI when: a) taking no medications, and b) when taking preventive medications (aspirin to prevent MI and stroke; statins to prevent MI; and antihypertensives to prevent stroke). Participants had a mean age of 76 ± 6 years and were on 10 ± 3 medications: 90% had hypertension, 76% had diabetes, 15% had prior MI, and 12% had prior stroke. Framingham data suggest the 10-year risk of MI in this population is close to 25%, which decreases to about 15% on aspirin or statins. 130/147 (87%) participants overestimated their risk of MI (48% estimated it at 75 or 100% over 10 years), 37 (24%) participants felt that aspirin provided at least a 50% absolute risk reduction in MI, and 33% of participants felt that statins could reduce MI risk by the same degree. However, 18% of participants felt that daily aspirin did not change their MI risk at all, and 20% felt a daily statin did not change their MI risk. For stroke, Framingham data suggest that 10-year risk in this population is close to 25%, which decreases to 15% on aspirin and antihypertensives. 128/149 (86%) participants overestimated their stroke risk, with 90 (60%) estimating that risk to be 75 or 100%. 46/147 (31%) participants estimated that aspirin could reduce provide a 50% absolute risk reduction in 10 year stroke risk, and 39% estimated that anti-hypertensives could provide at least a 50% absolute risk reduction. 18 (12%) participants felt that taking a daily aspirin, and 18% felt that taking a daily antihypertensive did not change their ten-year stroke risk. A large proportion of older males overestimated both their 10 year risk of MI and stroke. They also over- and under-estimated the magnitude of benefit conferred by aspirin, statins, and anti-hypertensive drugs in preventing these adverse clinical outcomes. Both findings have important implications for medication decision making, since under-estimation of benefits may play a role in non-adherence, while overestimation of benefits may result in tolerance of medication side effects with the expectation that they provide a greater degree of benefit. This study suggests the need for increased patient-physician communication regarding the risks and benefits of commonly prescribed preventive medications.

Comments

This thesis is restricted to Yale network users only. This thesis is permanently embargoed from public release.

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