魚油、阿斯匹靈無法降低透析時的AVF失敗風險


  【24drs.com】根據線上發表於1月3日JAMA內科醫學期刊的新研究結果,不論是魚類的omega-3脂肪酸或是阿斯匹靈,都無法預防血液透析患者的動靜脈廔管(arteriovenous fistulae,AVFs)失敗。
  
  西澳大學Fiona Stanely醫院腎臟科Ashley B. Irish醫師等人,檢測omega-3脂肪酸補充品對於為血液透析而設置的動靜脈廔管是否有保護效果。
  
  AVFs比合成移植物或中央靜脈導管更安全,但是,因為形成血栓或廔管成熟度不夠快,使得失敗率達20%-50%,此外,AVF失敗是血液透析患者發病和死亡的主要原因。
  
  作者們認為,補充omega-3脂肪酸促成安全地設置AVFs的因素很多:促進血管擴張和紅血球靈活性、降低血液黏度和發炎、抑制血小板凝集和平滑肌細胞增殖。
  
  不過,未曾就魚油或阿斯匹靈對於接受透析患者預防或降低AVF之失敗風險予以評估。
  
  麻州波士頓哈佛醫學院的Gregory Curfman醫師在編輯評論中寫道,AVF是動脈和靜脈之間直接手術吻合,是一個模型血管系統,在這種特殊形式的血管病理生理疾病中,相對高劑量的魚油在預防血栓形成或保持通暢方面缺乏效益,這些是負面的資料。
  
  有關飲食補充omega-3脂肪酸(EPA與DHA)對於心血管疾病後之次級預防的諸多臨床試驗,獲得的結果互相矛盾。
  
  開放標籤、非安慰劑控制研究顯示,曾發生心肌梗塞的患者中,心血管事件減少15% (GISSI, Prevenzione Study, 1999),高膽固醇血症患者中,嚴重冠狀血管事件減少19% (Japan Eicosapentanoic Acid Lipid Intervention Study, 2007)。另外,隨機雙盲、GISSI Heart Failure Study (2008)研究指出,曾發生心衰竭且接受omega-3脂肪酸補充品的患者,整體死亡率降低9%。
  
  不過,最近的雙盲評估指出,補充omega-3脂肪酸之後,對於心血管疾病的次級預防沒有好處,一篇納入超過20,000名患者的統合分析確認,缺乏好處。
  
  在目前這篇「Omega-3 Fatty Acids (Fish Oils) and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) 」研究中,Irish醫師等人著手評估每天4 g魚油用於第4或5期慢性腎病患者於血液透析前建立AVFs時,降低失敗率的效果。
  
  這篇隨機雙盲安慰劑控制試驗,納入英國、紐西蘭、馬來西亞、澳洲、35處血液透析中心,2008- 2014年間的567名成年患者,納入最後分析的患者有536人。
  
  最初,患者僅在12週時予以評估AVF中的早期血栓形成,但是研究者擴大為「建立廔管後12個月的AVF失敗」,其中還包括了放棄和/或管路設置失敗的分析。魚油的效果是主要目標,阿斯匹靈的效果是次要目標。
  
  隨機指定使用魚油的270名研究對象中,128人(47%)發生AVF失敗,安慰劑組的266人中有125人(47%)失敗(校正使用阿斯匹靈的相對風險 [RR]為1.03; P = .78)。
  
  特定事件分析獲得類似的結果:血栓形成(60 [22%] vs 61 [23%]; 校正RR, 0.98; P = .90)、放棄AVF(51 [19%] vs 58 [22%]; RR, 0.87; P = .43)、管路設置失敗(108 [40%] vs 104 [39%]; RR, 1.03; P = .81)。
  
  不過,在患有糖尿病的患者中,魚油對AVF失敗的影響達到顯著差異(相互影響P值 = .03; RR, 1.30 vs 0.85)。
  
  使用阿斯匹靈的結果與魚油類似;也就是說,沒有明顯的效果。阿斯匹靈組與安慰劑組的AVF失敗風險分別是 87 (45%) vs 83 (43%; RR, 1.05; P = .68)。
  
  研究結果發現,對於AVF失敗而言,相較於安慰劑組,阿斯匹靈並未產生效益(血栓形成:38 [20%] vs 35 [18%]; RR, 1.09; P = .70)、放棄AVF(46 [24%] vs 35 [18%]; RR, 1.31; P = .17)、管路設置失敗(73 [38%] vs 74 [38%]; RR, 0.99; P = .92)。
  
  研究者結論指出,未能證明魚油對AVF失敗有臨床相關影響。
  
  研究者指出,研究限制之一是,補充魚油時間太短(3個月),而他們選這時間點是因為AVFs通常在短時間內就達到成熟或失敗。他們認為,使用的阿斯匹靈劑量可能太低。
  
  不過,他們提醒,該研究並未發現缺乏效果的機轉。
  
  另外,他們觀察到,高失敗率仍然是成功血液透析的最重要障礙,並且,被患者和醫生認為是首要關鍵。
  
  資料來源:http://www.24drs.com/
  
  Native link:Fish Oil, Aspirin Do Not Lower AVF Failure Risk in Dialysis

Fish Oil, Aspirin Do Not Lower AVF Failure Risk in Dialysis

By Ricki Lewis, PhD
Medscape Medical News

Neither omega-3 fatty acids from fish nor aspirin prevented failure of arteriovenous fistulae (AVFs) in patients receiving hemodialysis, according to results of a new study published online January 3 in JAMA Internal Medicine.

Ashley B. Irish, MD, from the Department of Nephrology at Fiona Stanely Hospital and the University of Western Australia in Perth, and colleagues used the measure of whether AVFs created for hemodialysis failed as a way of testing the protective effects of omega-3 fatty acid supplementation.

AVFs are safer than synthetic grafts or central venous catheters, but failure rates are 20% to 50% as a result of thrombosis or failure of the fistulae to "mature" fast enough. In addition, AVF failure is a major cause of morbidity and mortality in patients receiving hemodialysis.

Supplementation with omega-3 fatty acids could facilitate creation of safe AVFs in several ways: promoting vasodilation and red blood cell flexibility, reducing blood viscosity and inflammation, and inhibiting platelet aggregation and smooth muscle cell proliferation, the authors suggest.

However, neither fish oil nor aspirin has previously been evaluated for preventing or lowering the risk for AVF failure in patients receiving dialysis.

In an accompanying editorial, Gregory Curfman, MD, from Harvard Medical School, Boston, Massachusetts, writes: "The [AVF], as a direct surgical anastomosis between artery and vein, is a model vascular system, and the lack of benefit of a relatively high dose of fish oil in preventing thrombosis or preserving patency provides negative data in this specific form of vascular pathobiologic disease."

Conflicting Prior Findings With Fish Oils for CVD Prevention

Several clinical trials have generated conflicting findings about the effect of dietary supplementation with omega-3 fatty acids (eicosapentaenoic acid and docosahexanoic acid) on secondary prevention after cardiovascular disease.

Open-label, nonplacebo-controlled studies demonstrated a 15% decrease in cardiovascular events among patients who had myocardial infarction (GISSI, Prevenzione Study, 1999) and a 19% decrease in major coronary events among patients with hypercholesterolemia (Japan Eicosapentanoic Acid Lipid Intervention Study, 2007). In addition, the randomized, double-blind GISSI Heart Failure Study (2008) indicated a 9% decline in overall mortality in patients who had heart failure and received omega-3 fatty acid supplementation.

However, more recent double-blind assessments have indicated no benefit in secondary prevention of cardiovascular disease after omega-3 fatty acid supplementation, and a meta-analysis that included more than 20,000 patients confirmed the lack of effect.

No Clinically Relevant Effect of Fish Oil on AVF Failure

In this current study, the Omega-3 Fatty Acids (Fish Oils) and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) trial, Dr Irish and colleagues set out to assess the role of 4 g/day fish oils to reduce failure of AVFs created for hemodialysis in patients with stage 4 or 5 chronic kidney disease.

The randomized, double-blind, placebo-controlled trial recruited 567 adults at 35 hemodialysis centers in the United Kingdom, New Zealand, Malaysia, and Australia from 2008 to 2014, including 536 patients in the final analysis.

At first, patients were assessed only at 12 weeks for early thrombosis in the AVF, but the investigators broadened that to "AVF access failure at 12 months after fistula creation," which also included analysis of abandonment and/or cannulation failure. Efficacy of fish oil was the primary objective, and that of aspirin the secondary objective.

Of the 270 participants randomly assigned to receive fish oil, 128 (47%) experienced AVF failure, as did 125 (47%) of 266 assigned to placebo (relative risk [RR] adjusted for aspirin use, 1.03; P = .78).

Analysis of specific events yielded similar findings: thrombosis (60 [22%] vs 61 [23%]; adjusted RR, 0.98; P = .90), AVF abandonment (51 [19%] vs 58 [22%]; RR, 0.87; P = .43), and cannulation failure (108 [40%] vs 104 [39%]; RR, 1.03; P = .81).

A significant difference in effect of fish oil on AVF failure did emerge among patients who also had diabetes mellitus, however (P = .03 for interaction; RR, 1.30 vs 0.85).

Results for aspirin use were similar to those for fish oil; that is, there was no apparent effect. Risk for AVF failure was 87 (45%) vs 83 (43%; RR, 1.05; P = .68) for aspirin vs placebo, respectively.

The findings also did not reveal an effect of aspirin compared with placebo on the components of AVF failure (thrombosis, 38 [20%] vs 35 [18%]; RR, 1.09; P = .70), AVF abandonment (46 [24%] vs 35 [18%]; RR, 1.31; P = .17), or cannulation failure (73 [38%] vs 74 [38%]; RR, 0.99; P = .92)

The researchers conclude that "a clinically relevant effect of fish oil on AVF failure was not demonstrated."

A limitation of the study may have been the brevity of fish oil supplementation (3 months), the researchers note, but they chose this endpoint because AVFs typically mature or fail in this timeframe. The aspirin dose may also have been too low, they suggest.

However, they caution that the investigation did not reveal the mechanism behind the lack of efficacy.

Still, the high failure rate "remains the most important impediment to successful hemodialysis and is considered a critical priority by patients and clinicians," they observe.

Eight coauthors report receiving grant funding from Abbott Products Operations A and Amgen Australia Pty Ltd.

JAMA Intern Med. Published online January 3, 2017.

    
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