Importance Reports of an obesity paradox have led to uncertainty about secondary
prevention in obese patients with stroke. The paradox is disputed and has been claimed to
be an artifact due to selection bias. Objective To determine whether the obesity paradox in
stroke is real or an artificial finding due to selection bias. Design, Setting, and Participants
We studied survival after stroke in relation to body mass index (BMI, calculated as weight in
kilograms divided by height in meters squared). To overcome selection bias, we studied only …