BMI Weighs Heavily on Ischemic Stroke Outcomes

LOS ANGELES, March 12 -- Longer institutional stays are the lot of overweight patients who suffer ischemic strokes, reported investigators here.

The higher the body mass index, the lower the likelihood that patients hospitalized for ischemic stroke would be discharged directly home, found Tannaz Razinia, B.S., and colleagues at the University of California at Los Angeles Stroke Center.

Stroke service patients who were morbidly obese went home directly from the hospital only about half as often as lean stroke patients, the investigators wrote in the March issue of Archives of Neurology. Heavier patients were more likely to go to rehab or to a skilled nursing facility.

The investigators examined whether BMI at admission would have an effect on discharge outcomes among 451 patients admitted to their service for treatment of ischemic strokes.

The patients were divided into four body-weight categories:

• Lean: BMI <25
• Overweight: BMI 25 to 29
• Obesity class I: BMI 30 to 34
• Obesity class 2: BMI > 35

Outcome measures included favorable functional outcome at discharge, defined as a Modified Rankin Scale score of 0 or 1, favorable discharge destination (patients sent home directly from the hospital stroke service, versus in-hospital transfer or discharge to rehabilitation or skilled-nursing facility), and reduced length of stay.

The authors also looked at other factors associated with outcomes after ischemic strokes, including age at admission, hypertension, atrial fibrillation, diabetes, systolic blood pressure on admission, stroke severity according to National Institutes of Health Stroke Scale score on admission, pre-morbid statin use, and stroke subtype per modified TOAST (Trial of ORG 10172 in Acute Stroke Treatment) classification.

The authors found that the leanest patients were significantly older and more likely to have a history of atrial fibrillation and coronary artery disease than those in the obesity class 2 group. Patients in the highest BMI category were significantly more likely than patients in the lowest category to have a history of diabetes, hyperlipidemia, and smoking.

In multivariate analysis, the investigators found that compared with the patients with lowest BMI, patients in the highest weight category were significantly less likely to be discharged directly home from the stroke service. The adjusted percentage for discharge home for the highest BMI group was 25.9 (95% confidence interval, 10.3-51.8) compared with 45.4 (95% CI, 36.9-54.1, P=0.04).

There was a trend for patients in the highest BMI group to have worse functional activity at the time of hospital discharge, but this difference was not statistically significant, the authors noted.

The heaviest patients also tended to have longer median hospital stays, at 6.3 days (range 4.5-8.2) vs. 5.1 (range 4.5-5.8) for the lightest patients (P for trend =0.08).

There were no significant differences in in-hospital mortality among the four BMI groups.

"In summary, this study suggests that hospitalized obese individuals may have poorer discharge clinical outcomes than their leaner counterparts," the authors conclude. "Future studies are required to confirm these results and to identify the pathophysiologic mechanisms at play. In the interim, our study provides further impetus for identifying and appropriately treating obese individuals at risk for first and recurrent stroke."

The authors noted that whiles BMI data for some patients were not measured directly but came from patients themselves or their family members, self-reports of height and weight have shown to be reliable from other studies,

They also noted that the small number of fatalities did not allow for a more detailed analysis of associations between BMI and mortality after ischemic stroke, they added.

The study was funded by the National Institute of Neurological Disorders and Stroke. The authors had no financial disclosures.