Conference Coverage

Does BMI affect outcomes after ischemic stroke?


 

FROM AAN 2019

High body mass index (BMI) is associated with reduced mortality and reduced disability after acute ischemic stroke, according to research that will be presented at the annual meeting of the American Academy of Neurology.

“One possible explanation is that people who are overweight or obese may have a nutritional reserve that may help them survive during prolonged illness,” said Zuolu Liu, MD, of the University of California, Los Angeles, in a press release. “More research is needed to investigate the relationship between BMI and stroke.”

The obesity paradox was first noted when studies suggested that being overweight improved survival in patients with kidney disease or heart disease. Investigators previously examined whether the obesity paradox is observed in stroke, but their studies were underpowered and produced ambiguous results.

Dr. Liu and colleagues sought to evaluate the relationship between BMI and 90-day outcomes of acute ischemic stroke. They examined data for all participants in the FAST-MAG trial, which studied whether prehospital treatment with magnesium improved disability outcomes of acute ischemic stroke. Dr. Liu and colleagues focused on the outcomes of death, disability or death (that is, modified Rankin Scale score of 2-6), and low stroke-related quality of life (that is, Stroke Impact Scale score less than 70). They analyzed potential relationships with BMI univariately and in multivariate models that adjusted for 12 prognostic variables, such as high blood pressure, high cholesterol, and smoking.

Dr. Liu’s group included 1,033 participants in its study. The population’s mean age was 71 years, and 45.1% of the population was female. Mean National Institutes of Health Stroke Scale (NIHSS) score was 10.6, and mean BMI was 27.5 kg/m2.

The investigators found an inverse association between the risk of death and BMI. Adjusted odds ratios for mortality were 1.67 for underweight participants, 0.85 for overweight participants, 0.54 for obese participants, and 0.38 for severely obese participants, compared with participants of normal weight. Similarly, the risk of disability had a U-shaped relationship with BMI. Odds ratios for disability or death were 1.19 for underweight participants, 0.78 for overweight participants, 0.72 for obese participants, and 0.96 for severely obese participants, compared with participants of normal weight. This relationship was attenuated after adjustment for other prognostic factors, however. Dr. Liu’s group did not find a significant association between BMI and low stroke-related quality of life.

The study was limited by the fact that all participants were from Southern California, which potentially reduced the generalizability of the results. The racial and ethnic composition of the study population, however, is similar to that of the national population, said the researchers.

No study sponsor was reported.

SOURCE: Liu Z et al. AAN 2019, Abstract P3.3-01.

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