Obesity paradox in stroke – Myth or reality? A systematic review

Abstract

Background and purposeBoth stroke and obesity show an increasing incidence worldwide. While obesity is an established risk factor for stroke, its influence on outcome in ischemic stroke is less clear. Many studies suggest a better prognosis in obese patients after stroke (“obesity paradox”). This review aims at assessing the clinical outcomes of obese patients after stroke by performing a systematic literature search.MethodsThe reviewers searched MEDLINE from inception to December 2015. Studies were eligible if they included outcome comparisons in stroke patients with allocation to body weight.ResultsTwenty-five studies (299’750 patients) were included and none was randomised. Ten of 12 studies (162’921 patients) reported significantly less mortality rates in stroke patients with higher BMI values. Seven of 9 studies (92’718 patients) ascertained a favorable effect of excess body weight on non-fatal outcomes (good clinical outcome, recurrence of vascular events). Six studies (85’042 patients) indicated contradictory results after intravenous thrombolysis (IVT), however. Several methodological limitations were observed in major part of studies (observational study design, inaccuracy of BMI in reflecting obesity, lacking body weight measurement, selection bias, survival bias).ConclusionMost observational data indicate a survival benefit of obese patients after stroke, but a number of methodological concerns exist. No obesity paradox was observed in patients after IVT. There is a need for well-designed randomized controlled trials assessing the effects of weight reduction on stroke risk in obese patients.

Body Mass Index and Clinical Outcomes in Large Vessel Occlusion Acute Ischemic Stroke after Endovascular Therapy

“…Similar findings were observed in other studies, such as in the Telemedical Project for Integrative Stroke Care (TEMPiS) trial [8]. On the other hand, other investigators showed results contradicting the latter with no improved outcomes in overweight or obese patients [10-14]. A recent meta-analysis including 25 studies and around 300,000 patients found that there was no obesity paradox in patients receiving intravenous thrombolysis [14].…”

“…On the other hand, other investigators showed results contradicting the latter with no improved outcomes in overweight or obese patients [10-14]. A recent meta-analysis including 25 studies and around 300,000 patients found that there was no obesity paradox in patients receiving intravenous thrombolysis [14]. The authors identified several methodological/design concerns that may have led some investigators to conclude that overweight and obesity were associated with better outcomes.…”

“…In fact, patients who had more severe strokes were missing BMI data, which may have influenced the observed results. Second, time to follow-up in those studies varied greatly ranging from 1 week to 11.5 years, which could be too short to uncover any harmful effects of obesity on outcomes [14]. Third, these results could be explained by a confounding bias.…”

“…The ischemic tissue volume (ischemic core) was defined by a voxel relative cerebral blood flow of < 30% of the normal tissues. The total hypoperfused volume was defined by > 6 s delay in the time-to-maximum of the tissue residue function and a penumbral volume of at-risk tissue defined by the difference between total hypoperfused and ischemic core tissue estimates [14]. …”

“…In fact, several studies have shown a better clinical poststroke outcome in obese patients than in those of normal weight, a phenomenon commonly described as the “obesity paradox,” such as better functional outcomes, lower re-hospitalization rates, and lower rates of stroke reoccurrence [5-9]. Nevertheless, reports have been widely conflicting, and explanations currently remain ambiguous [10-14]. …”