Thursday, August 4, 2011

Better Questions, Better Answers, Better Solutions

Often, when we are struggling to make good decisions, the problem is not the quality of the data available… it is the quality of the question.  This is because the threshold for achieving actionable knowledge is dependent on the question being asked. The more simple and specific you make the question, the easier it is to gather enough information to reach the threshold for actionable knowledge. If the question being asked is too broad, the question itself may prevent the creation of actionable knowledge.

A perfect example of this in the medical field is the current discussion about salt intake. The main concern is the sodium component of salt. Diets high in sodium have been associated with increased rates of hypertension, which is clearly linked to an increased chance of heart attack and stroke. Because of these associations, there has been a public health campaign to advise adults in the US to reduce their salt intake. However, the campaign to reduce salt consumption has recently become controversial. This controversy stems from asking a question that is too broad to facilitate the creation of actionable knowledge. The question being asked is “What should we tell the US adult population about salt intake?”

A recent article in the Archives of Internal Medicine demonstrated a reduction in cardiovascular mortality associated with lower sodium diets. The study was statistically adjusted to be a representative sample of the US population. This article gives the appearance of creating sufficient actionable knowledge to tell the US population to eat less salt. However, two other recent studies create serious doubts about that conclusion. The first study, published in the New England Journal of Medicine, was also a study modeling the US and showed that the mortality benefit for a lower sodium diet had a significantly larger impact for blacks than for whites. The second article, published in the Journal of the American Medical Association, was a European study that only looked at a relatively young and healthy white cohort; this study demonstrated a large increase in mortality for the subjects with the lowest sodium diets.

These articles appear to disagree and there have been discussions about the methods of each study. No study is perfect and the conclusions from any of the three may be proven incorrect, but it is also possible that all three may be correct. It is possible that young and healthy whites in Europe may be harmed by a diet that restricts salt intake. Sodium is necessary for several biological functions. However, white, young, and healthy only represent a small group in a study that utilizing a sample representative of the adult US population. The potential harm to the white, young, and healthy cohort may be washed out by the benefits for other groups.

These studies create debate because the question being asked is too broad. If you believe that eating less salt will harm a cohort of people, it is unethical to tell them to do so. If you are then trying to take action based on the question “What should we tell the US adult population about salt intake?” you have quite a dilemma.

I suggest in these cases you don’t try to solve that dilemma with more data, information and knowledge. You solve it by changing the question. If some groups are helped by an action and others harmed, the question should not be “what advice do we give the whole population?” The question should be “how do I advise each cohort in the population?”

With regard to salt intake, we should stop asking “what should we tell the US adult population about salt intake?” and start asking "who in the US do we need to tell to eat less salt?"

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