At the center of the conversation between the medical and legal professions over the place of malpractice litigation in our society, is a debate regarding the existence of “defensive medicine.” Both physicians and attorneys are attempting to improve health care. Nonetheless, doctors contend they are “forced” to order unnecessary tests in order to protect themselves from lawsuits. They blame legal pressure for out of control costs and complications. Given that we would hope that our physicians would make decisions based solely our welfare, this idea is disturbing. Is it true?
In order to study the idea of defensive testing, it is necessary to look at the process of medical diagnosis. We may then be able to judge the potential for litigation to affect it.
When presented with a patient, a physician will first gather basic information. This data will come from what the patient says, history about the patient’s past, physical exam and any immediately available tests. The doctor creates a list of possibilities, which might explain these preliminary findings. This list of hypotheses is a differential diagnosis.
How long should this list be? Should it include both very likely and very unlikely possibilities? For example, in a patient with chest pain after a car accident, you might explain the pain by a broken rib. However, you could also explain chest pain by a heart attack, which lead to the car accident. How about a blood clot? An esophageal tear? Pneumonia? Pericarditis? A hidden gunshot wound?
The length of the differential diagnosis will lead directly to the number of tests.
In creating a differential, a doctor balances two opposite philosophical ideas. The first is Occam’s Razor. This logic concept says that in choosing between multiple possibilities, always chose the simplest. As every medical student is taught, “When you hear huff beats, think horses, not zebras.” Using this theory of medical hypotheses, the differential diagnosis list should be short (i.e. rib fracture and heart attack).
However, on the other side of the scale is Hickam’s dictum. Apparently a physician who had seen too many “zebras,” Dr. Hickam stated “patients can have as many diseases as they damn well please.” By this theory, the differential diagnosis list can be extremely long and even approach the bizarre (the patient inhaled a bee while driving which stung him and thus chest pain).
These two forces are always in play in every doctor’s mind. A shorter differential list is usually correct, requires the least tests, and produces the fastest answer. However, occasionally, a diagnosis is missed and a patient suffers. A long differential results in excess testing, will take longer with more complications, and will frighten the patient. However, the long list will miss fewer zebras.
Every time they see a patient, doctors try to make a decision regarding the length of the differential and therefore how many tests. Into this mix is thrown the hesitation of the patient to undergo tests, the need for speed in finding dangerous conditions (which may be high or low on the list), the doctor’s personal experience, and the willingness of insurance companies to pay for testing.
Does the threat of a malpractice lawsuit affect Occam vs. Hickam? If the doctor knows missing a 1 in 200 disease, such as pericarditis, will not only hurt the patient but might put the doctor on the witness stand, does the physician listen to Hickam’s “many diseases” and order the echocardiogram? Knowing that the echo is only correct 90 percent of the time does the physician then order the cardiology consult? Does the cardiologist order another test (say a Trans-Esophageal Echo) to “cover” himself?
It is impossible for any study or any doctor to state exactly how much the threat of litigation affects the medical decision making process. The factors are varied and each case is different. We would like to think that doctors always put their patient’s health first and leave the law to the lawyers. However, given the delicate nature the diagnostic process and the strong physician perception of legal pressure, this is highly unlikely.
If the threat of malpractice suits results in excess testing, it may cause damage beyond costs and the risk of the tests themselves. Crabtree’s Bludgeon proposes an extreme but relevant observation. It puts us in a situation where decision-making spins completely out of control. The Bludgeon states, “No set of mutually inconsistent observations can exist for which some human intellect cannot conceive a coherent explanation, however complicated.” In other words, if our differential diagnosis lists are too long, and we test too much and we produce too much useless data, it will result in ridiculous diagnoses and worthless medical care.
A goal of the legal system is to support quality medical care and to assist patients harmed by error. However, the health and life of patients is dependent on complex individual decisions. The future of our health care system and its costs require objective analysis. It is likely that our present malpractice environment perturbs the vital process of testing and diagnosis. Perhaps, we need to find a solution that will free us all from the influence of care by court.