http://www.blackswanreport.com/blog/2012/06/nonlinearity-of-iatrogenics/
Second principle of iatrogenics: it is not linear. I do not believe that we should take risks with near-healthy people; I also believe that we should take a lot, a lot more risks with those deemed in danger.
Why do we need to focus treatment on more serious cases, not marginal ones? Take this example showing nonlinearity. When hypertension is mild, say marginally higher than the zone accepted as “normotensive”, the chance of benefiting from the drug is close to 5.6% (only one person in eighteen benefit from the treatment). But when tension is considered to be in the “high” or “severe” categories, the chance of benefiting are now 26% and 72%, respectively (that is that one person in four and two persons out of 3 will benefit from the treatment). So the treatment benefits are convex to condition (the benefits rise disproportionally, in an accelerated manner). But consider that the iatrogenics should be near-constant for all categories! In the very ill condition, the benefits are large relative to iatrogenics, in the borderline one, they are small. This means that we need to focus on high symptom conditions and ignore, I mean really ignore, other situations in which the patient is not very ill.
Another way to view it is by considering that mother nature had to have tinkered through selection in inverse proportion to the rarity of the condition. Of the hundred of thousands of drugs today, I can hardly find a via positiva one that makes a healthy person unconditionally “better”. And the reason we have not been able to find drugs that make us feel unconditionally better when we are well (or unconditionally stronger, etc.) is for the same statistical reason: nature would have found this magic pill. But consider that illness is rare, and the more ill the person the less likely nature would have found the solution, in an accelerating way. A condition that is three deviations away from the norm is more than three hundred times rarer than normal; an illness that is five deviations from the norm is more than a million times rarer!
The medical community does not seem to grasp such nonlinearity of benefits to iatrogenics, and if they do so in words, they have not integrated it into a decision-making methodology. Pharmaceutical companies under financial pressures to find diseases (thanks to “efficiency” they are fragile, a few medications away from bankruptcy, so they need to use their large machinery to generate revenues). They have been scraping the bottom of the barrel, looking for disease among healthier and healthier people, and lobbying for reclassifications of conditions. Now if your blood pressure is in the upper part of the range that used to be called “normal”, you are no longer “normotensive” but “pre-hypertensive”, even if there are no symptoms in view. There is nothing wrong with the classification if it leads to healthier lifestyle and robust measures, typically via negativa —but what is behind, typically, is a drive for more medication.
Another way to view it: the iatrogenics is in the patient, not the treatment. If the patient is close to death, all speculative treatments should be permitted —no holds barred. Conversely, if the patient is near healthy, then mother nature should be the doctor.