Friday, January 10, 2014

The "Prevention" Bait-and-Switch: Inverse Benefit Rides Again

I recently suggested that we should rename the so-called "risk-benefit ratio" the harm-hope ratio:

I suggested this because it matters what we call things. The names we use over time shape our thinking.

In a similar vein I have been pondering the significant change in the way we use the term "preventive medicine." This change is extremely important because we have granted prevention in medicine a status right up there with motherhood and apple pie. All sorts of things that would never pass the sniff test otherwise are swallowed whole so long as we call them "prevention." So prevention "creep" is potentially quite a serious issue.

Once upon a time we understood exactly what preventive medicine meant. We should live healthy lives, and thereby prevent ourselves from getting sick in many instances. To do this we mostly had to adopt healthy lifestyles.

When we regarded preventive medicine in this way, two important implications followed. First, there are numerous advantages to healthy lifestyles, so even if we failed to prevent a particular, feared outcome, such as heart attacks, the individual patient was very likely to accrue significant health benefits. Put in today's statistical terms, the number needed to treat (NNT) for some sort of patient benefit was very low, i.e., favorable. The second implication was that healthy lifestyles are quite safe as a rule. It was quite unlikely that we'd cause anyone's health to deteriorate by promoting this sense of "prevention."

Well, that was then. Today, we seem to equate "preventive medicine" with swallowing a boatload of pills.

Speaking to this topic are my colleagues Meta Kreiner and Linda Hunt of the anthropology department at Michigan State, whom I introduced a while ago:
Drs. Kreiner and Hunt continue to report on the same study of primary care practice I mentioned in that earlier post, this time in a sociology journal (subscription required).

The authors looked especially at hypertension and diabetes diagnoses in these clinical practices. The physicians tended to swallow current guidelines completely and were eager to diagnose "pre-diabetes" and "pre-hypertension." But far from encouraging lifestyle changes for people at risk for progressing to more serious problems, they saw these "pre" states as demanding aggressive drug therapy. Drs. Kreiner and Hunt attribute a  lot of this impulse to the wide use of NCQA guidelines to track individual physician performances, so failure of one's patient to hit a target blood pressure or glycohemoglobin level quickly could jeopardize one's "report card" and perhaps deny one a bonus payment.

They also discovered that the patients generally failed to distinguish "pre" from "real." So far as patients were concerned, they had a dread disease and the physician was doing them a big favor by throwing a bunch of meds at them. While attributing a good deal of what they saw to the ascendency of evidence-based medicine,they apparently saw no sign in any of these encounters of providers explaining NNT to patients or giving them any choice in deciding how aggressively they needed to jump on mild deviations from normal in otherwise healthy people. Meanwhile, many of these patients encountered severe adverse reactions to their meds, which usually meant that more meds were added on to counter the adverse effects.

Drs. Kreiner and Hunt prefer an analysis that shows all this as an inappropriate slide from a population health perspective to an individual patient perspective.  They suggest that from a public-health standpoint it makes perfect sense to try to reduce the total load of diabetes and hypertension in the population. Trouble is, "An individual walking into a doctor's office does not come there with the intention of improving the health profile of the population, but is there to pursue betterment of their own health. To enlist them unwittingly into the project of prevention, while exposing them to potential harm,...raises serious ethical concerns."

The authors add astutely that another problem with this system is its fallaciously self-justifying nature: "Should the patient experience increasingly poor health, it is taken by both clinician and patient as confirmation that early or incipient disease had been identified. On the other hand, should the patient never develop illness, it is viewed not as diagnostic error but as a triumph of preventive medicine over disease." The fallacy here is the same as overdiagnosis through cancer screening tests such as PSA--the patient who has a high PSA level, and who then undergoes radical prostatectomy and ends up impotent and incontinent, never reasons that he could have lived all the rest of his life with no symptoms from his so-called "cancer" and instead credits his surgeon with having saved his life.

While the authors cite Don Light's and my paper on the Inverse Benefit Law:
--my own take on their observations would be slightly different. Instead of focusing on the public vs. individual health, I would more directly apply the ideas of NNT and inverse benefit. I would, in the process, blame drug industry marketing for a large part of the problem they have so well described. It's not an accident that we have so come to de-emphasize lifestyle interventions and focus instead solely on medications. It's no accident that we've expanded the definition of "at risk" to include populations where the NNT gets higher and higher (less and less favorable). It's no accident that when we throw medications at patients with very high NNT, the chances for adverse reactions far outnumber the chances of benefit. It's no accident that accumulating evidence that chasing arbitrary target numbers with more and more meds fails to produce good medical outcomes is systematically ignored by physicians. All of this reflects a concerted, coordinated drug marketing juggernaut that sees huge profits in convincing previously healthy people to take more and more drugs.

By physicians and the public at large so uncritically adopting the shibboleth of "preventive," we created a huge opening for the drug industry merketers, and they proceeded to drive the proverbial truck through it.

Kreiner MJ, Hunt LM. The pursuit of preventive care for chronic illness: turning healthy people into chronic patients. Sociology of Health & Illness 2013; doi: 10:1111/1467-9566.12115 (epublished ahead of print)


Judy B said...

Well said! I removed myself from the medical industry because of all this! My former doctor totally ridiculed my lifestyle changes! Drugs were the only things that mattered....

aelephant said...

This brought to mind the analysis of Spyros Makridakis on Hypertension, which is largely NOT evidence-based. PDF is linked here for those interested:

John said...

All sorts of things that would never pass the sniff test otherwise are swallowed whole so long as we call them "prevention".............
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