Risk comm guru Gigerenzer argues that absolute risk communication is a moral issue

Professor Gerd Gigerenzer of the Max Planck Institute for Human Development in Berlin is one of the world’s leaders in risk communication. He teaches doctors, policy-makers, journalists and the general public.

He has written before about how misleading communication of risk is a moral issue for medical journals, for journalists, for researchers, and for anyone who communicates to the public about health care issues. For example, see his October editorial in the BMJ. Excerpt:

“In 1995, the UK Committee on Safety of Medicines issued a warning that third generation oral contraceptive pills increased the risk of potentially life threatening thrombosis twofold. The news provoked great anxiety, and many women stopped taking the pill, which led to unwanted pregnancies and abortions–some 13 000 additional abortions in the next year in England and Wales–and an extra £46m (€55m; $71m) in costs for the NHS. Yet how big was the twofold risk? The studies revealed that for every 7000 women who took the earlier, second generation pills, one had a thrombosis, and this number increased to two in women who took third generation pills. The problem of misleading reporting has not gone away. In 2009, the BMJ published two articles on oral contraceptives and thrombosis; one made the absolute numbers transparent in the abstract, whereas the
other reported that “oral contraceptives increased the risk of venous thrombosis fivefold.”

These two examples illustrate a general point. Absolute risks (reductions and increases), such as from one to two in 7000, are transparent, while relative risks such as “twofold” provide incomplete and misleading risk information. Relative risks do not inform about the baseline risk–for example, whether twofold means from one to two or from 50 to 100 in 7000–and without this information, people overestimate benefits or harms. In the case of the pill scare, the losers were women, particularly adolescent girls, taxpayers, and the drug industry. Reporting relative risks without baseline risk is practised not only by journalists because big numbers make better headlines or by health organisations because they increase screening participation rates. The source seems to be medical journals, from which figures spread to press releases, health pamphlets, and the media.”

Last week, at the Salzburg Global Seminar, “The Greatest Untapped Resource in Healthcare? Informing and Involving Patients in Decisions about Their Medical Care,” Gigerenzer addressed the issue again. He framed misleading communication of risk as a barrier to shared decision-making.

Another note: e-patient Dave has posted another reflection on what he learned at the Salzburg Global Seminar, calling Jack Wennberg’s practice variation research “an essential e-patient awareness topic.”

Here’s a photo of the Schloss Leopoldskron, site of the seminar. You can learn more about the Schloss here.


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