Which has a Higher Hazard Ratio: Smoking or Obesity?

May 25, 2019

Do you think smoking or obesity would have a higher hazard ratio? When looked at in context, the answer might surprise you. Hazard ratio (HR) is the ratio of the hazard rates corresponding to the conditions described by two levels of an explanatory variable. The HR has also been defined as the ratio of (risk of outcome in one group)/(risk of outcome in another group), occurring at a given interval of time. In the situation where the hazard for an outcome is exactly twice in Group A than in Group B, the value of the hazard ratio would be 2.0.

If I told you that a completely man-made and preventable plague was spreading across the United States and would affect 75% of the population within twenty years, causing countless deaths and cost over $215 billion per year, you might pay attention. Like most epidemics, obesity is accelerating and now affects 17% of all children and adolescents in the United States — triple the rate from just one generation ago.

Obese children are more likely to become obese adults and carry a significantly higher negative lifetime economic and medical burden. If you are overweight or obese, there is a 90% chance you will develop type 2 diabetes; yet, if you smoke for 30-40 years, you have a 10-17% chance of developing lung cancer.

If asked which they were most afraid of, being overweight or smoking, most people would likely think smoking is more deadly. (This is not intended to suggest smoking is beneficial; it’s intended to frame the issue in context.)

In the not-too-distant future, I predict that vegetable oils, refined carbohydrates, and grain-based products will be viewed with the same disdain as cigarette smoking is.