Saturday, August 13, 2016

The Enemy of Good is Better: Maximizing versus Satisficing in Clinical Medicine

Herbert Simon, Nobel Laureate
Recently I was called to admit a little old lady with a digoxin overdose who had symptomatic bradycardia.  She was in her 70s, had Alzheimer's disease (AD) and a medication list that would not print on one page.  I immediately thought, what benefit does digoxin have that justifies even the occasional admission for toxicity?  That's a good question in its own right, but consider a partial list of her other medications:

  1. pantoprazole
  2. lisinopril
  3. gabapentin
  4. raloxifene
  5. estradiol
  6. donepezil
  7. labetolol
  8. furosemide
  9. glipizide
  10. fenofibrate
  11. memantine
  12. sitagliptin
  13. spironolactone
  14. amlodipine
  15. alprazolam
  16. aspirin
One certainly must wonder what goals her providers are trying to achieve with these and indubitably some other medications which aren't listed.  Her husband was frustrated when I told him that many of the medications she is taking are not really doing her any good.  "They why do they have her taking them?" was a question I could not answer, because it doesn't make sense to me either.  Exasperated, he offered a great analogy:  "Suppose you hire me as a contractor to build you a home, and I tell you that you need to build a 14 foot high retaining wall in the back yard, two feet thick, reinforced with rebar and containing 20 yards of concrete.  Would that be responsible unless it were absolutely necessary?  What kind of contractor would recommend something you didn't really need?"

"A physician contractor," came the ready answer in both of our minds, and we simultaneously nodded in understanding.

While in many instances it is clear that physicians are acting as nefarious money-grubbers, I doubt this was the case for this woman's primary provider and his polypharmacy-bent prescription pen.  There is another explanation:  he appears to lack common sense in prescribing because he is, by training or habit of personality, acting like a maximizer, as opposed to a satisficer.

Herbert Simon, winner of the 1978 Nobel Prize in economics was instrumental in explaining why normative theories of decision making and economic choice, such as Expected Utility Theory (EUT) are frequently violated by people making real life choices.  His theory of "bounded rationality" can be summed up in one quote:
"If there were no limits to human rationality, administrative theory would be barren.  It would consist of the single precept: Always select the alternative, among those available, which will lead to the most complete achievement of your goals."
Normative theories such as EUT assume people are maximizers - that they have no limits on intelligence, will power, information, computational abilities, time, etc.  For a mazimizer, optimal or maximal achievement of the goal at hand is the decision making directive (whatever it may be and whether or not it is carefully considered alone and in relation to competing goals).  Many people, especially physicians, have maximizing tendencies in at least some domains.  Alternatively, satisficers are willing to satisfy or suffice in the achievement of a goal.  "Leave good enough alone" or "if it ain't broke don't fix it" are heuristics that appeal to satisficers.  Indeed, in most domains and for most people, limitations on time and resources lead to decisions that result from satisficing.

In the case of my poor little digoxin poisoned patient, her physician can be inferred to be trying to maximize the treatment of her hypertension (amlodipine, lisinopril, spironolactone, labetolol), heart failure (digoxin, lasix, spironolactone, labetolol), AD (donepezil, memantine), diabetes (glipizide, sitagliptin), among others.  But is maximal treatment actually a good goal in her case, given her age, dementia, life expectancy, and tolerance of physical and financial side effects?  Is the maximization strategy hamstrung by her physician's limited ability to calculate, estimate, or anticipate the various side effect and interactions lurking in her polypharmacy potpourri?  Is his maximization strategy doomed and she as a result?

I think Simon explained what is going on here too:
"The human being striving for rationality and restricted within the limits of his knowledge has developed some working procedures that partially overcome these difficulties. These procedures consist in assuming that he can isolate from the rest of the world a closed system containing a limited number of variables and a limited range of consequences."
Maximizing physicians are often maximizing only one of the parameters relevant to human health and prosperity.  By maximizing a simplified and artificially constrained goal such as the blood pressure number or glycated hemoglobin result, they have ignored other determinants of patients' well-being such as freedom from side effects, complexity, and financial burdens.  They are satisficers in disguise - they're satisficing by wholesale sacrifice of entire categories of patients' preference sets.  Their rationality is bounded artificially in a way that facilitates the physician's goals, rather than the patient's goals.

If we are ultimately going to satisfice by necessity, and I think we have to, our satisficing ought to involve a rational search for goals, possibilities, and evidence.  If my patient's physician had conducted such a search, he may have determined that a blood pressure of 150, a glycated hemoglobin of 9, and a little ankle edema are a small price for a little old lady with AD to pay for freedom from half a dozen medications and that occasional week long admission to the hospital to treat medication induced complications.

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