MedWire News: People who have had a stroke survive longer if they are overweight or obese, a study suggests.

The researchers explain that the effects of obesity on cardiovascular risk are often mediated through other factors, but their findings suggest that obese people if otherwise healthy may fare as well as lean individuals after a stroke.

The trial of more than 20,000 stroke patients showed that overweight patients were about a quarter less likely to die in the 5 years after a stroke than patients with a healthy weight. And underweight patients faced a markedly worse prognosis.

Tom Olsen (Stroke Unit, Hvidovre University Hospital, Denmark) and co-workers studied data from a Danish registry of stroke patientsk, including the results of brain scans, which reveal the severity and type of the patient's stroke.

Olsen and colleagues divided almost 22,000 patients into five groups based on their body mass index: underweight, normal weight, overweight, obese and severely obese.

Results showed that being overweight significantly protected against death in the 5 years after a stroke.

Compared with patients with a healthy weight, overweight patients were 27% less likely to die, while obese and severely obese patients shared a 16% lower risk.

In contrast, underweight patients were 63% more likely to die in the 5 years after a stroke than those with a healthy weight.

The scale of the obesity problem in the USA has more than doubled since the late 1970s. About a third of Americans are now obese.

In view of their findings, published in the journal Neuroepidemiology, the researchers say that body mass index may be a poor indicator of person's risk for cardiovascular disease and suggest that measuring waist-to-hip ratio may be better.