Background: To make informed decisions, patients must have adequate knowledge of key decision-relevant facts.
Objective: To determine adults' knowledge about information relevant to common types of medication, screening, or surgery decisions they recently made.
Setting: National sample of US adults identified by random-digit dialing.
Design: Cross-sectional survey conducted between November 2006 and May 2007.
Participants: A total of 2575 English-speaking adults aged 40 y or older who reported having discussed the following medical decisions with a health care provider within the previous 2 y: prescription medications for hypertension, hypercholesterolemia, or depression; screening tests for colorectal, breast, or prostate cancer; or surgeries for knee/hip replacement, cataracts, or lower back pain.
Measurements: Participants answered knowledge questions and rated the importance of their health care provider, family/friends, and the media as sources of information.
Results: Accuracy rates varied widely across questions and decision contexts. For example, patients considering cataract surgery were more likely to correctly estimate recovery time than those patients considering lower back pain or knee/hip replacement (78% v. 29% and 39%, P < 0.001). Similarly, participants were more knowledgeable of facts about colorectal cancer screening than those who were asked about breast or prostate cancer. Finally, respondents were consistently more knowledgeable on comparable questions about blood pressure medication than cholesterol medication or antidepressants. The impact of demographic characteristics and sources of information also varied substantially. For example, blacks had lower knowledge than whites about cancer screening decisions (odds ratio [OR] = 0.57; 95% confidence interval [CI] = 0.43, 0.75; P = 0.001) and medication (OR = 0.77; 95% CI = 0.60, 0.97; P = 0.03) even after we controlled for other demographic factors. The same was not true for surgical decisions.
Limitations: The questions did not measure all knowledge relevant to informed decision making, were subject to recall biases, and may have assessed numeracy more than knowledge.
Conclusions: Patient knowledge of key facts relevant to recently made medical decisions is often poor and varies systematically by decision type and patient characteristics. Improving patient knowledge about risks, benefits, and characteristics of medical procedures is essential to support informed decision making.