The Association of Body Mass Index With Health Outcomes: Causal, Inconsistent, or Confounded?

摘要

According to the definition of confounding in a causal diagram, the association of body mass index (weight (kg)/height (m)2) with health-related outcomes is almost always noncausal, attributable to confounding by weight and perhaps height. The same conclusion holds for any other deterministic derivation from weight and height. No causal knowledge is gained by estimating a nonexistent effect of body mass index.