Uncertainty of risk estimates from clinical prediction models: rationale, challenges, and approaches
BMJ 2025; 388 doi: https://doi.org/10.1136/bmj-2024-080749 (Published 13 February 2025) Cite this as: BMJ 2025;388:e080749
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Dear Editor
Congratulations to Riley et colleagues for highlighting the importance of presenting uncertainty around risk estimates provided by clinical prediction models (1). As nicely reviewed by the authors, there are numerous causes of uncertainty and bias due to poor methodological standards and inappropriate risk prediction model development techniques, poor model stability, or insufficient external evaluation.
A deeper reason of overlooking uncertainty in prediction models stems from the confusion between risk and disease. As argued by Aronowitz, "one underappreciated consequence of modern clinical and public health practices is that the experience of being at risk for disease has been converging with the experience of disease itself" (2). This conflation between risk and disease is the result of increased biological, clinical, and epidemiological knowledge on the risk particularly of chronic diseases, and more specifically of the application of a population perspective to individual-level clinical care which feeds the false notion that a prediction accurate at a population or group level could be directly applied to an individual patient.
One harmful effect of ignoring uncertainty in clinical prediction models arises when these predictions are translated into clinical decision rules (3). While risk predictions are intended to guide preventive services and treatments at a group level, it is tempting but deceptive to apply them bluntly to individual patient decisions—on a case-by-case basis—to simplify the inherently complex nature of clinical judgment (3). This reflects the unfulfilled promise of a data-driven personalized medicine trying to overcome the failure of epidemiology in knowing who is and who is not eventually getting the disease (4, 5).
We agree with Riley et al. that improving the communication of uncertainty in risk prediction is essential. However, this should be accompanied by the acknowledgement of the complexity of clinical decision-making, emphasizing that, regardless of the level of risk prediction certainty, randomness always plays a role at the individual level (5).
References
1) Riley RD, Collins GS, Kirton L, Snell KI, Ensor J, Whittle R, Dhiman P, van Smeden M, Liu X, Alderman J, Nirantharakumar K, Manson-Whitton J, Westwood AJ, Cazier JB, Moons KGM, Martin GP, Sperrin M, Denniston AK, Harrell FE Jr, Archer L. Uncertainty of risk estimates from clinical prediction models: rationale, challenges, and approaches. BMJ. 2025; 388:e080749.
2) Aronowitz RA. The converged experience of risk and disease. Milbank Q. 2009 Jun;87(2):417-42.
3) Gérvas J, Starfield B, Heath I. Is clinical prevention better than cure? Lancet. 2008; 372(9654):1997-9.
4) Chiolero A. There is nothing personal. Arch Intern Med. 2012; 172(21):1691-2.
5) Smith GD. Epidemiology, epigenetics and the 'Gloomy Prospect': embracing randomness in population health research and practice. Int J Epidemiol. 2011; 40(3):537-62.
Competing interests: No competing interests
Dear Editor
Adding a measure of uncertainty to uncertainty in prediction is certainly valuable (1), but not sufficient, with uncertainty not bounded. Adding chaos and complexity thinking helps us understand the emergence of extreme adverse or beneficial outcomes despite their prediction (2,3).
Low risk patients get “unexpected” consequential events like heart disease, heart attacks, sudden death, cancer, etc. Chaos and complexity science explains this and the sometimes unpredictable timing of events, which would improve management and prevention.
A 26 year old man awoke with chest pain, an “unexpected” heart attack from LAD occlusion.
A 32 year old woman with an abnormal screening exercise test had severe RCA stenosis.
A 50 year old cardiologist died in his sleep with “unexpected” 95% stenosis of 3 vessels.
A 60 year old woman had SD precipitated by the “unexpected” sudden death of her friend.
None of these were predicted or predictable by current prediction models or by quantification of uncertainty of their occurrence, but explainable by chaos and complexity. Similar examples exist throughout and beyond medicine, as in the weather, life, health, society, nature, the planet and the universe, as examples of order and chaos in the universe (2,3).
66 million years ago, an asteroid hit the Yucatan peninsula, an act of chaos (real physics and chaos science), wiping out the dinosaurs, a consequential low probability event that paved the way for us to emerge, with changing probabilities of smaller asteroids heading our way. There are parallels between asteroids and heart attacks, cancer, etc, poised at the edge of chaos.
In addition to quantifying uncertainty of risk, we suggest learning and teaching chaos and complexity science to understand the emergence of extreme adverse or beneficial events, to guide prevention and to manage, in and beyond medicine and health (4,5).
References
1 Riley R, Collins G, Kirton L, et al. Uncertainty of risk estimates from clinical prediction models: rationale, challenges, and approaches. BMJ 2025; 388:e080749 doi: https://doi.org/10.1136/bmj-2024-080749 (Published 13 February 2025)
2 Rambihar VS, Rambihar SP, Rambihar VS Jr. Tsunami Chaos and Global Heart: using complexity science to rethink and make a better world. 2005. Vashna Publications. Toronto, Canada.
http://www.femmefractal.com/FinalwebTsunamiBK12207.pdf
3. Palmer T. Why the world feels so unstable right now. BBC. 5 Feb 2023. https://www.bbc.com/future/article/20230203-why-the-world-feels-so-unsta...
4 Rambihar VS. Medical schools should teach chaos and complexity thinking.
BMJ 2023; 383:p2412 doi: https://doi.org/10.1136/bmj.p2412 available full text as BMJ Rapid Response to Launer J. Living with uncertainty, Opinion. BMJ 2023; 382 doi: https://doi.org/10.1136/bmj.p2052
5 Fraser S, Greenhalgh T. Coping with complexity: educating for capability. BMJ 2001; 323 doi: https://doi.org/10.1136/bmj.323.7316.799
Competing interests: No competing interests
Use Chaos and Complexity Science to better understand uncertainty, improve health and achieve change – from Cos to Cosmos.
Dear Editor
Responding to Riley and coauthors’ article on uncertainty in risk estimates (1), Chiolero agrees with Riley and coauthors that improving the communication of uncertainty in risk prediction is essential, writing “However, this should be accompanied by the acknowledgement of the complexity of clinical decision-making, emphasizing that, regardless of the level of risk prediction certainty, randomness always plays a role at the individual level” (2).
Randomness is not the only cause of unpredictability, and acknowledgement of complexity should be followed by the need to understand the unusual features of chaos and complexity science and complex systems, for individuals and populations - sensitive dependence on initial conditions, self organization, emergence and uncertainty.
A 2023 BMJ Letter to the Ed (3), suggests that medical schools should teach chaos and complexity thinking to understand uncertainty, and to address complex issues in and beyond medicine, an idea extended to CPD for physicians, health professionals and the general public, to address issues in medicine, health and society (4).
Uncertainty and unpredictability should could lead to action, using chaos and complexity as a powerful tool for creativity and change, described in a free book online – “Tsunami Chaos Global Heart: using complexity science to rethink and make a better world” (5), and in Brian Klaas’ 2025 Book “Fluke: Chaos, Chance and why everything we do matters.”
These ideas were used in health promotion and advocacy for three decades, and in a recent talk “Preventing Premature Heart Disease,” responding to increasing NCDs and premature heart disease, and continuing unexpected unpredicted sudden death globally.
We should go beyond acknowledgement of complexity in clinical decision making, and randomness, to use ideas from chaos and complexity science, to better understand uncertainty and create change to make a better world, from medicine and health to everything else – from Cos to Cosmos (5).
References
1 Riley R, Collins G, Kirton L, et al. Uncertainty of risk estimates from clinical prediction models: rationale, challenges, and approaches. BMJ 2025; 388:e080749 doi: https://doi.org/10.1136/bmj-2024-080749 (Published 13 February 2025)
2 Chiolero A. Confusion between population-risk prediction and individual disease. Rapid Response. https://www.bmj.com/content/388/bmj-2024-080749/rr-1
3 Rambihar VS. Medical schools should teach chaos and complexity thinking.
BMJ 2023; 383:p2412 doi: https://doi.org/10.1136/bmj.p2412 available full text as BMJ Rapid Response to Launer J. Living with uncertainty, Opinion. BMJ 2023; 382 doi: https://doi.org/10.1136/bmj.p2052
4 Rambihar VS, Rambihar SP, Rambihar VS Jr. Chaos, Complexity, Complex Systems, Covid19: 30 years teaching health professionals chaos and complexity. 2020 Poster, 10th International Conference on Complex Systems. https://static1.squarespace.com/static/5b68a4e4a2772c2a206180a1/t/5f1f12...
5 Rambihar VS, Rambihar SP, Rambihar VS Jr. Tsunami Chaos and Global Heart: using complexity science to rethink and make a better world. 2005. Vashna Publications. Toronto, Canada.
http://www.femmefractal.com/FinalwebTsunamiBK12207.pdf
Competing interests: No competing interests