Response to Denise Minger 6: Number Needed to Treat

Response to Denise Minger,
Part 6: Number Needed to Treat

Ms Minger says I am wrong to question the accuracy of Harriet Hall’s statement that if former President Clinton followed Caldwell Esselstyn’s advice, he could never eat another avocado.

Here she has me totally nailed. Esselstyn is only OK with avocados for those without heart disease. My apologies to Harriet Hall for my error. Ms Minger, thank you for that catch.

I’m guessing Esselstyn is basing his caution on information like this but I don’t know for sure.

 I still think it is an embarrassment that she refers to The International Network of Cholesterol Skeptics as though they are a reliable and respected source of information. At least she seems to understand that high LDL is a significant risk factor for heart disease.

I want to read to you an excerpt of Dr Hall’s blog post with my comments now. In referring to President Clinton’s new diet, she says, “Such drastic diet restrictions must be tested more carefully before any widespread adoption can be recommended.” Why? What is she worried about? Is she totally unaware of the research on diet and heart disease? When she looks around at how most Americans eat, does she really think they would be doing any worse for their health on a whole food plant-based diet? Doesn’t she know that most diet-related illnesses like diabetes, obesity, and heart disease are extremely unlikely to be promoted by such a diet, to put it mildly? She asks, “Are these people getting adequate nutrition? Does the diet increase the risk of other diseases?” Dr Hall, there is plenty of research on this already. Vegan diets are considered safe and healthy by major health institutions provided they are well-planned. Does she think typical Americans are getting adequate nutrition? She goes on, “Is the benefit worth the difficult lifestyle modifications?” Well, Dr Hall, if plant-based diets were adopted in a widespread fashion, as you say, the market would cater to people’s preferences so it wouldn’t be difficult. It really is not that difficult now. She continues. “What is the number needed to treat (NNT) to prevent one heart attack? What NNT would compensate for giving up the enjoyment of favorite foods for the rest of your life?” This, my friends, is a bad attitude, plain and simple.

To me this is a little like a doctor questioning whether the benefits of giving up smoking are worth the lost enjoyment to the smoker. I don’t see much difference between the smoking that caused the damage to the lung you see on the left and the cholesterol-raising diet that caused the atheroma on the right. There is very little chance either would have developed had their owners’ lifestyles been sufficiently focused on prevention.

Her use of the concept of number needed to treat seems to me to be totally inappropriate. Usually number needed to treat is discussed in reference to the value of a drug or other medical therapy. It is intended to clarify how many adverse events, such as fatal heart attacks, would be prevented in a population using the therapy.

I don’t understand why she thinks this is an appropriate metric for assessing a diet. First, a whole food plant-based diet offers obvious health benefits without side effects such as those that occur with drugs. Number needed to treat is a way of subjecting drug therapies to a cost/benefit analysis in evidence-based medicine. So what are the costs of following a healthy diet? What are the problematic side effects of a healthy diet?

Why evaluate a diet simply by adverse events avoided? Let’s imagine we have a hypothetical dietary trial that shows such a diet can spare one out of ten people a heart attack over ten years. What’s the cost to the other nine? Why would you assume that just that one among the ten would be the only person to experience a benefit? Maybe all ten will report weight loss or better energy levels. Maybe another won’t develop diabetes. Maybe someone else will sleep better. Maybe yet another will no longer be constipated. A healthy diet is not a targeted drug intervention, Dr Hall. It can help overall health. I’m sorry you can’t write a prescription for a drug that can do better.

I’m afraid it’s this undue skepticism of preventive and non-pharmacological approaches to our health challenges by some doctors that alienate many people from evidence-based medicine today. Some people understand how much better a proper diet can help them feel. They don’t see fruits and vegetables as a therapy for disease. They see them as the right and proper fuel for the human body, without which diseases like diabetes develop. They may not see diet as something hard to change; in fact they may find their new diet to be rewarding and enjoyable in unexpected ways. Hearing such skepticism from a doctor, some will doubt that they can get reliable health information from the mainstream and may be drawn instead to woo. Dr Hall, you may be having the opposite effect of what you intend. In reference to this slide, I would agree that following a balanced raw vegan diet requires extraordinary commitment, but a healthy plant-based diet really is not that hard to stick with these days.

When I see results like this, I have a hard time seeing how a physician can say, “Yeah, well maybe vegetarian diets can improve health, but won’t you miss those juicy steaks?” My response is that any doctor claiming to represent science should stick to the science. I’m skeptical of anyone who thinks personal preferences and cravings make for persuasive arguments. I don’t find that rational. I find that emotional. Maybe if the Skepdoc had her own quadruple bypass, she might have a lesser valuation of the few moments she is stimulated by her ice cream.

That’s the end of my response to Denise Minger. For all my criticisms of her, Minger kept her critique of me civil and I am grateful for that. I cannot say the same of Anthony Colpo. Mr Colpo made the mistake of writing under the influence of hostile emotions. He made himself an easy target. I start my session with this confusionist pinata next.