Dynamics of obesity paradox after stroke, related to time from onset, age, and causes of death

OBJECTIVE: Paradoxical longevity in obese patients with established disease has been documented in various conditions. We aimed to find whether such a relationship exists in ischemic stroke patients, with stratified analyses according to time of death after stroke, age, and cause of death. METHODS: The Korean Stroke Registry (KSR) is a nationwide, multicenter, prospective registry of acute stroke. For 7.5 years, data on 34,132 patients with acute ischemic stroke were collected through KSR, and their mortality information was ascertained through a governmental statistical office. We assessed relative hazard of mortality according to obesity status. RESULTS: Stroke survivors whose body mass index (BMI) values were lower than the chosen reference level of 20-23 had increased risks of long-term mortality (hazard ratio HR of 1.36 and 95% confidence interval CI of 1.25-1.48 for BMI ≤18.5; HR of 1.14 and 95% CI of 1.03-1.26 for BMI 18.5-20), whereas obese stroke patients had decreased risks of mortality (HR of 0.83 and 95% CI of 0.74-0.92 for BMI 27.5-30; HR of 0.77 and 95% CI of 0.63-0.93 for BMI 30-32.5). Inverse association between obesity status and mortality was not evident until 90 days after stroke but became significant 1 year after onset of stroke. Such an association was more prominent in stroke patients who were less than 65 years old, but it remained constant in all age groups. The paradoxical relationship remained significant, regardless of causes of death. CONCLUSIONS: Our results documented obesity paradox in stroke survivors, regardless of age and causes of death, and it became evident a sufficient time after stroke onset.