The obesity paradox in stroke: lower mortality and lower risk of readmission for recurrent stroke in obese stroke patients.

BACKGROUND: Although associated with excess mortality and morbidity, obesity is associated with lower mortality after stroke. The association between obesity and risk of recurrent stroke is unclear. AIMS: The study aims to investigate the association in stroke patients between body mass index and risk of death and readmission for recurrent stroke.
METHODS: An administrative Danish quality-control registry designed to collect a predefined dataset on all hospitalized stroke patients in Denmark 2000–2010 includes 45 615 acute first-ever stroke patients with information on body mass index in 29 326. Data include age, gender, civil status, stroke severity, computed tomography, and cardiovascular risk factors. Patients were followed up to 9·8 years (median 2·6 years). We used Cox regression models to compare risk of death and readmission for recurrent stroke in the four body mass index groups: underweight (body mass index < 18·5), normal weight (body mass index 18·5–24·9), overweight (body mass index 25·0–29·9), obese (body mass index ≥ 30·0).
RESULTS: Mean age 72·3 years, 48% women. Mean body mass index 23·0. Within follow-up, 7902 (26·9%) patients had died; 2437 (8·3%) were readmitted because of recurrent stroke. Mortality was significantly lower in overweight (hazard ratio 0·72; confidence interval 0·68–0·78) and obese (hazard ratio 0·80; confidence interval 0·73–0·88) patients while significantly higher in underweight patients (hazard ratio 1·66; confidence interval 1·49–1·84) compared with normal weight patients. Risk of readmission for recurrent stroke was significantly lower in obese than in normal weight patients (hazard ratio 0·84; confidence interval 0·72–0·92).
CONCLUSIONS: Obesity was not only associated with reduced mortality relative to normal weight patients. Compared with normal weight, risk of readmission for recurrent stroke was also lower in obese stroke patients.