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Primer: demystifying risk—understanding and communicating medical risks

Nature Clinical Practice Rheumatology volume 3, pages 181–187 (2007)Cite this article

Abstract

Assessments of risk are a critical part of the practice of evidence-based medicine. Comprehension of various risk measures, such as absolute risk, relative risk, attributable risk, odds ratio, and hazard ratio, is essential to understand the medical literature, and to communicate health risks effectively. Complex risk measures, including number needed to treat and survival estimates that are adjusted for competing risks, are often misunderstood. Communication of these concepts to patients can be a challenge. The patient's perception of risk stems not only from the way risks are stated, but also from family history, personal experiences, cultural norms, and beliefs. A multifaceted approach to risk communication that uses both qualitative and quantitative assessments of risk, and addresses the timing and permanence of risks, is necessary to ensure the patient understands the potential risks. Successful communication involves interaction with the patient to understand the patient's perspective and to aid in personalized decision-making. In the face of uncertainty, making a provisional decision with a plan to review it later can be a good strategy. Verifying the patient's comprehension can help ensure that the decisions reached are informed and acceptable.

Key Points

  • The absolute risk, risk difference, relative risk and odds ratio are risk measures that pertain to the development of an outcome at a specific time point (fixed-time measures)

  • The risk ratio and hazard ratio are risk measures that pertain to the rate of development of an outcome over a period of time (rate-based measures)

  • Many complex risk measures, such as the number needed to treat, relative risk reduction, and survival estimates adjusted for competing risks, are derived from other risk measures

  • The patient's perception of risk stems from many sources, such as family history, personal experiences, cultural norms, and beliefs

  • Physicians should engage in a thorough discussion, which addresses the timing, permanence and severity of risks, and uses a variety of risk measures, to ensure that patients understand the potential risks

  • Making a provisional decision based on current information and perceptions with a planned review at a later date is a reasonable approach in the face of uncertainty, because it allows for inclusion of new information

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Figure 1: The cumulative incidence of heart failure in 575 patients with time after a diagnosis of rheumatoid arthritis

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Authors and Affiliations

  1. EL Matteson is Professor of Medicine and Chair of the Division of Rheumatology, and Chair of the Department of Health Sciences Research, CS Crowson is a statistician, TM Therneau is Associate Professor of Biostatistics, and SE Gabriel is Professor of Epidemiology and Medicine, all at the Mayo Clinic, Rochester, MN, USA.,

    Cynthia S Crowson, Terry M Therneau, Eric L Matteson & Sherine E Gabriel

Authors
  1. Cynthia S Crowson
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  2. Terry M Therneau
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  3. Eric L Matteson
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  4. Sherine E Gabriel
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Corresponding author

Correspondence to Cynthia S Crowson.

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The authors declare no competing financial interests.

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Crowson, C., Therneau, T., Matteson, E. et al. Primer: demystifying risk—understanding and communicating medical risks. Nat Rev Rheumatol 3, 181–187 (2007). https://doi.org/10.1038/ncprheum0397

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