Full-body MRI risk-benefit equals a year of smoking, analysis shows
A routine scan's net benefit is 926 micromorts—same as avoiding 10,000 km on motorcycle
The article, linked from LessWrong, breaks down Scott Alexander's earlier analysis of full-body MRI screening for asymptomatic people. The net benefit per scanned individual is 0.025 quality-adjusted life years (QALYs)—a small but positive expected value. The author converts this into micromorts (a million micromorts = one death) using a derived exchange rate of 1 QALY = 37,000 micromorts. The result: the MRI nets about 926 micromorts of reduced risk, equivalent to one year of smoking, a high-risk pregnancy, climbing the Matterhorn, riding 10,000 km on a motorcycle, or two BASE jumps.
This framing helps people intuitively weigh medical tests against everyday risks. The author notes skepticism around asymptomatic screening due to base-rate fallacies, but acknowledges the MRI delivers a real—if modest—benefit. The comparison to vivid, high-risk activities (e.g., a day on the Ukraine frontline) makes the abstract QALY metric actionable for personal health decisions.
- Net benefit of 0.025 QALYs per person from a full-body MRI, based on Scott Alexander's breakdown
- Conversion to micromorts yields 926 micromorts—equal to one year of smoking or two BASE jumps
- Author remains skeptical of asymptomatic screening but provides relatable risk context for decision-making
Why It Matters
Translates medical risk-benefit into everyday terms, helping professionals make informed screening choices.