脳卒中とTIA後のObesity Paradox

脳卒中とTIA後の生命予後は過栄養と肥満のほうがよいという肥満パラドックスをみた観察研究を紹介します。

Wolfram Doehner, et al. Overweight and obesity are associated with improved survival, functional outcome, and stroke recurrence after acute stroke or transient ischaemic attack: observations from the TEMPiS trial. Eur Heart J (2012) doi: 10.1093/eurheartj/ehs340

対象はTEMPiS trialに登録された脳卒中もしくはTIA患者のうち、BMIの情報があった1521人です。BMIは低栄養18.5未満、正常BMI18.5～25、過栄養BMI25～30、肥満BMI30～35、高度肥満BMI35以上の5群に分類しています。

一次アウトカムは発症30カ月後の死亡率と非致死性アウトカム（脳卒中再発、要施設入所、機能障害Barthel Index60未満）です。結果ですが、BMIが高いほどこれらのアウトカムがよく、低いほど予後が悪いという結果でした。これより肥満パラドックスを認めるという結論です。

TEMPiS trial参加者4428人中、BMIのデータがあるのが1521人しかないため、選択バイアスが存在する可能性があります。またヨーロッパでの研究結果ですので、日本の脳卒中患者ではObesity Paradoxは当てはまらないかもしれません。

Abstract

Aims The aim of the study was to evaluate the association of the body mass index (BMI) with mortality and with non-fatal functional outcome in patients with acute stroke or transient ischaemic attack (TIA). Obesity is an established risk factors in primary cardiovascular disease prevention including stroke. The impact of overweight in patients with stroke or TIA on secondary fatal and non-fatal functional outcomes is less well established.

                   

Methods and results Data from 4428 patients with acute stroke or transient ischaemic attack (TIA) from the Telemedical Project for Integrative Stroke Care (TEMPiS) were studied in this post hoc analysis. The body mass index was available in 1521 patients. Patients were categorized as underweight (BMI <18 .5=".5" 18.5="18.5" 25="25" 30="30" advanced="advanced" all="all" kg="kg" m="m" normal="normal" obesity="obesity" overweight="overweight" sup="sup" to="to">2

), and no body weight assessed. Outcome measures after 30 months were all-cause mortality and non-fatal outcomes: recurrent stroke, need for institutional care, and functional impairment (Barthel index <60 modified="modified" rankin="rankin" score="score">3). Mortality risk was lower in overweight patients [hazard ratio (HR): 0.69, 95% confidence interval (CI): 0.56–0.86) and lowest in obese (HR: 0.50, 95% CI: 0.35–0.71) and very obese patients (HR: 0.36, 95% CI: 0.20–0.66] compared with normal BMI. Functional, non-fatal outcomes, and recurrent stroke followed the same inverse pattern: underweight patients had the worst outcomes but obese patients had better outcomes than patients with normal BMI (all P < 0.01). After adjustment for multiple confounding factors, obese patients had a lower risk of the combined endpoints of death or institutional care (OR: 0.60, 95% CI: 0.38–0.92), death or high dependency (OR: 0.60, 95% CI: 0.39–0.91) and death or recurrent stroke (OR: 0.56, 95% CI: 0.37–0.86). Mortality was significantly lower in obese patients (all BMI >30 kg/m²) than patients with normal weight (HR: 0.70; 95% CI: 0.50–0.98). Underweight patients had consistently the highest risks for all endpoints.

Conclusion Overweight and obese patients with stroke or TIA have better survival and better combined outcomes of survival and non-fatal functional status than patients with the BMI <25 kg="kg" m="m" sup="sup">2

.