Different Ways to Describe the Benefits of Risk-Reducing Treatments

A Randomized Trial

19 June 2007 | Volume 146 Issue 12 | Pages 848-856

Background: How physicians communicate the risks and benefits of medical care may influence patients' choices. Ways to communicate the benefits of risk-reducing drug therapies include the number needed to treat (NNT) to prevent adverse events, such as heart attacks or hip fractures, and gains in disease-free life expectancy or postponement of adverse events. Previous studies suggest that the magnitude of the NNT does not affect a layperson's decision about risk-reducing interventions, but postponement of an adverse event does affect such decisions.

Objective: To examine laypersons' responses to scenarios that describe benefits as postponing an adverse event or the equivalent NNT.

Design: Cross-sectional survey with random allocation to different scenarios.

Setting: General community.

Participants: Respondents to a population-based health study.

Intervention: The survey presented scenarios regarding a hypothetical drug therapy to reduce the risk for heart attacks (1754 respondents) or hip fractures (1000 respondents). The data sources for both scenarios were clinical trials. Respondents were randomly assigned to a scenario with 1 of 3 outcomes after 5 years of treatment. For the drug to prevent heart attacks, the outcomes were postponement by 2 months for all patients, postponement by 8 months for 1 of 4 patients, or an NNT of 13 patients to prevent 1 heart attack. For the drug to prevent hip fractures, the outcomes were postponement by 16 days for all patients, postponement by 16 months for 3 of 100 patients, or an NNT of 57 patients to prevent 1 fracture.

Measurements: Consent to receive the intervention and perceived ease of understanding the treatment effect.

Results: The overall rate of response to the survey was 81%. In the heart attack scenarios, 93% of respondents who were presented with the NNT outcome consented to drug therapy, 82% who were presented with the outcome of large postponement for some patients consented to therapy, and 69% who were presented with the outcome of short postponement for all patients consented to therapy (chi-square, 89.6; P < 0.001). Corresponding consent rates for the hip fracture scenarios were 74%, 56%, and 34%, respectively (chi-square, 91.5, P < 0.001). Respondents who said that they understood the treatment effect were more likely to consent to therapy.

Limitation: Decisions were based on hypothetical scenarios, not real clinical encounters.

Conclusions: Treatment effects expressed in terms of NNT yielded higher consent rates than did those expressed as equivalent postponements. This result suggests that the description of the anticipated outcome may influence the patient's willingness to accept a recommended intervention.

Editors' Notes Context In previous research, different ways of describing the outcomes of an intervention led to different health care decisions. Contribution Healthy people were randomly assigned to receive equal but different descriptions of the outcome of a hypothetical intervention to prevent myocardial infarction (MI). Responders were more likely to consent to treatment when the outcome was described as the number needed to treat to prevent 1 MI. They were less likely to consent when the intervention was described as not preventing but delaying an MI by 2 months for all persons or by 8 months for 25% of persons. Caution The scenarios were presented in a survey and were hypothetical. Implication Quantitatively equal but differently worded outcomes elicit different health care decisions. —The Editors

 

Author and Article Information

From the University of Southern Denmark, Odense, Denmark; University of Tromsø, Tromsø, Norway; and Norwegian Institute of Public Health and University of Oslo, Oslo, Norway.

Acknowledgments: The authors thank Arthur Elstein, Dorte Gyrd-Hansen, Jørgen Nexøe, and Henrik Støvring for comments on the paper. The authors also thank the residents of Finnmark, Norway, for their willingness to contribute to the study and the Norwegian Institute of Public Health for conducting the practical part of the data collection.

Grant Support: By governmental funds held by the University of Tromsø, Tromsø, Norway.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Peder A. Halvorsen, MD, Nordlys Legesenter, N-9509 Alta, Norway; e-mail, phalvor{at}online.no.

Current Author Addresses: Dr. Halvorsen: Nordlys Legesenter, N-9509 Alta, Norway.

Dr. Selmer: Division of Epidemiology, Norwegian Institute of Public Health, PO Box 4404, Nydalen, N-0403 Oslo, Norway.

Dr. Kristiansen: Institute of Health Management and Health Economics, University of Oslo, PO Box 1089, Blindern, N-0317 Oslo, Norway.

Author Contributions: Conception and design: P.A. Halvorsen, R. Selmer, I.S. Kristiansen.

Analysis and interpretation of the data: P.A. Halvorsen, I.S. Kristiansen.

Drafting of the article: P.A. Halvorsen, I.S. Kristiansen.

Critical revision of the article for important intellectual content: R. Selmer, I.S. Kristiansen.

Final approval of the article: P.A. Halvorsen, R. Selmer, I.S. Kristiansen.

Statistical expertise: R. Selmer.