the “obesity paradox” found in several studies is that normal or underweight people have higher mortality, esp if they have chronic diseases. overall, studies with longer-term databases have found this to be less true, suggesting reverse causality: those with lower weight may disproportionately include people with underlying diseases causing them to lose weight. the current study, a large study with a remarkably good/complete database, adds to this (see doi:10.1001/jamaneurol.2014.1017). results:
–71617 patients admitted to Danish hospitals from 2003-2012 with a stroke, with information on BMI in 53,812. looked at deaths likely caused by the index stroke (if the death occurred within the first week or month after the stroke), and recorded in the Danish Stroke Register (coverage felt to be >80% complete).
–mean age 71.2, 47% women, 8% hemorrhagic stroke, mean BMI=25.7, with 10% underweight, 39% normal wt, 35% overwt, and 17% obese.
–within the first week of stroke, 4373 pts died with 3334 (4.7% of total) dying of stroke. no difference in risk of death from stroke by BMI (except in the underweight group)
–within first month, 7878 died and 5512 (7.7%) from stroke. no difference in risk of death from stroke by BMI (except in the underweight group)
–those with the lowest BMI tended to have the most severe stroke (stroke severity score), even controlling for age, sex, stroke subtype, cardiovasc risk factors, civil and socioeconomic status.
–BUT, there was an inverse relationship between BMI and age of admission for stroke — as compared to normal weight patients, those overweight had stroke 3 years earlier and obese 6 years earlier.
so, in general this study supports recommendation to achieve a normal body weight, despite the mixed messages from some of the other studies. the issue with underweight individuals continues to be muddied. this group (likely) includes normal underweight people (who might actually have a lower stroke mortality) along with some with significant medical or mental illnesses associated with both underweight and higher mortality.
geoff