How Helpful Are New Drugs? Not So Clear

Tyler Cowen links to a paper by Frank Lichtenberg, an economist at Columbia University, that tries to estimate the benefits of drug company innovation by estimating how much new drugs prolong life compared to older drugs. The paper compares people equated in a variety of ways except the “vintage” (date of approval) of the drugs they take. Does taking newer drugs increase life-span? is the question Lichtenberg wants to answer. He concludes they do. He says his findings “suggest that two-thirds of the 0.6-year increase in the life expectancy of elderly Americans during 1996-2003 was due to the increase in drug vintage” — that is, to newer drugs.

An obvious problem is that Lichtenberg has not controlled for health-consciousness. This is a standard epidemiological point. People who adopt Conventional Healthy Behavior X (e.g., eat less fat) are more likely to adopt Conventional Healthy Behavior Y (e.g., find a better doctor) than those who don’t. For example, a study found that people who drink a proper amount of wine eat more vegetables. Another reason for a correlation between conventionally-healthy practices is mild depression. People who are mildly depressed are less likely to do twenty different helpful things (including “eat healthy” and “find a better doctor”) than people who are not mildly depressed. (And mild depression seems to be common.) Perhaps doctors differ. (Lichtenberg concludes there are big differences.) Perhaps better doctors (a) prescribe more recent drugs and (b) do other things that benefit their patients. Lichtenberg does not discuss these possibilities.

A subtle problem with Lichtenberg’s conclusion that we benefit from drug company innovation is that drug-company-like thinking — the notion that health problems should be “solved” with drugs — interferes with a better way of thinking: the notion that to solve a health problem, we should find out what aspects of the environment cause it. I suppose this is why we have Schools of Public Health — because this way of thinking, advocated at schools of public health, is so incompatible with what is said and done at medical schools. Public health thinking has a clear and impressive track record — for example, the disappearance of infectious disease as a major source of death. There are plenty of other examples: the drop in lung cancer after it was discovered that smoking causes lung cancer, the drop in birth defects after it was discovered that folate deficiency causes birth defects. Thinking centered on drugs has done nothing so helpful. Spending enormous amounts of money to develop new drugs shifts resources away from more cost-effective research: about environmental causes and prevention. Someone should ask the directors of the Susan K. Komen Foundation: Why “race for the cure”? Wouldn’t spending the money on prevention research save more lives?


7 Replies to “How Helpful Are New Drugs? Not So Clear”

  1. This is a little uncharitable it seems to me. Drug vintage isn’t correlated with BMI, smoking status or a large number of medical conditions. If what you’re saying were true, we wouldn’t expect this. Those using newer drugs should be healthier. You need to have a more sophisticated story to refute Lichtenberg’s argument.

    Seth: I think Lichtenberg — and anyone else who wants to know the value of new drugs — should consider these alternatives. Perhaps there is data that will help assess them. Lack of significant correlation with BMI, etc., isn’t much of an argument. Let’s take BMI. Maybe current advice about how to reduce BMI isn’t very good? Lots of people are health-conscious and weigh more than they would like. Take smoking. Maybe this is heavily determined by culture? Take Medical Condition X. Maybe we don’t know how to prevent Medical Condition X? So that even people who do conventionally healthy things (e.g., “eat healthy”) still have Medical Condition X at the same rate as those who don’t eat healthy. Maybe these indices of health (BMI, etc.) are insensitive? Because if people live longer, shouldn’t they be healthier (weigh less, etc.) while they are alive?

    Quite apart from that, lack of significant correlation with BMI, etc., does nothing to refute the possibility that good doctors help their patients in important ways besides prescribing newer drugs.

  2. But what is healthy eating?

    Obviously it must include fish and chips for Friday lunch, bacon and egg at least once a week, the occasional beer, a glass of wine with dinner most evenings, toast and marmalade at breakfast, lots of tea and coffee, and plenty of smoked salmon, sardines, mackerel pate, pork pies, muscat grapes, cherries in brandy, hummus and olives, apples and cheese, duck, lamb, roast vegetables, baked potatoes, watercress sandwiches, parsnip soup, … and generally Things I Like.


  3. “the disappearance of infectious disease as a major source of death. ”

    Are not drug companies are due a lot of the credit, for example through developing the manufacture of penicillin ? Without drugs, would not infectious diseases such as tuberculosis still be a terrible scourge ?

    Seth: Drug companies did not invent vaccines. Far from it.

  4. It is a bit of a stretch to say that the new drug vintage patients are likely to be healthier on unobservables when they are not healthier on observables. Obviously it is theoretically possible as you point out, but why is it probable?

    I completely agree with the doctors point, by the way. That is a valid criticism of this research design.

    Seth: What do you mean by “the doctors point”? I’m afraid I don’t understand.

  5. I meant that physicians who prescribe newer vintages might help their patients in other ways. This is a different from saying that patients who are prescribed newer vintages are different from those who aren’t.

    Seth: Thanks for clarifying that.

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