Describe Treatment Pros and Cons With Simple Statistical Terms

You can help patients put scientific findings and statistics into perspective...to help them weigh treatment benefits and risks

Patients often see or hear misleading claims from the media or ads...and need your expertise to understand them.

Discuss study results using ABSOLUTE risk...not RELATIVE risk.

These terms convey a very different message...even though they're based on the same results.

Relative risk explains the chance of an outcome in the treatment versus control group...and it sounds more impressive. Absolute risk tells the ACTUAL difference in outcomes...and is often much smaller.

For example, you might explain risk like this: "A statin can reduce the relative risk of a first heart attack by 25%. But this turns out to be an absolute difference of only 2.9%...from 12.2% of patients not on a statin compared to 9.3% of patients on one."

Patients may also hear that statins increase the risk of diabetes by about 9%. But explain the difference in absolute risk is just 0.4%...from 4.5% of patients not on a statin to 4.9% of patients who are.

Convert percentages to frequencies...to simplify the message.

For example, you can tell patients that statins are linked to diabetes in 4 out of 1,000 patients...instead of saying 0.4% of patients.

Or consider explaining the number needed to treat (NNT) and number needed to harm (NNH) to compare benefits and risks.

To calculate this, just divide 100 by the absolute risk difference. For example, the NNT to prevent one CV event with a statin is 100 divided by 2.9...or about 35 patients.

And the NNH for statins to cause one case of diabetes is 100 divided by 0.4...or about 250 patients.

So in this case, taking a statin for 4 to 5 years may prevent one CV event in 35 patients...at the cost of diabetes in one in 250.

For more tips, see our commentary, Applying Study Results to Patient Care.

• Other: Glossary of Study Design and Statistical Terms
• Other: Applying Study Results to Patient Care