Monday, August 20, 2012

Communication of Risk to Patients: Context Matters

The internet can be tremendous resource and can minimize information asymmetry, particularly between doctor and patient. Unfortunately, there is a lot of medical misinformation out on the web as much of it is not subject to medical peer review and written by advocacy groups.  A challenge facing physicians is how to effectively communicate information and opinion about risk so that informed decision making between doctor and patient genuinely occurs.

Here is an article, on explaining risks to patients, that was brought to my attention by my colleague Dr. Michael Stevens. Two important points I would like to mention:

First, the authors suggest that using information about relative risk without reference to absolute risk should be avoided. Here is an example:
  • Treatment X can reduce the risk of Outcome Y by 50% (this is a relative risk reduction) when compared to no treatment. However the absolute risk (risk without treatment) of Outcome Y is 1 in 1,000,000.  Thus, the relative risk reduction with Treatment X is from 1 to 0.5 per 1,000,000.  The overall impact of the Treatment X is very small given the already very low risk of the Outcome Y. Framing the discussion exclusively in terms of relative risk reduction (50% in this example) is misleading.
Second, the authors suggest that visual representations of risk may be effective for informing patients. As an infectious diseases physician, I am vexed when patients refuse vaccination on the grounds that thimerosol (a mercury containing preservative) will cause them toxicity and harm. These fears abound despite no convincing evidence of harm caused by low doses of thimerosol in vaccines. So here is a visual aid for those who fear thimerosol, many of whom, however, eat fish because of presumed health benefits.

A picture is worth a thousand words.

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