鱼油、阿斯匹灵无法降低透析时的AVF失败风险


  【24drs.com】根据在线发表于1月3日JAMA内科医学期刊的新研究结果,不论是鱼类的omega-3脂肪酸或是阿斯匹灵,都无法预防血液透析患者的动静脉廔管(arteriovenous fistulae,AVFs)失败。
  
  西澳大学Fiona Stanely医院肾脏科Ashley B. Irish医师等人,检测omega-3脂肪酸补充品对于为血液透析而设置的动静脉廔管是否有保护效果。
  
  AVFs比合成移植物或中央静脉导管更安全,但是,因为形成血栓或廔管成熟度不够快,使得失败率达20%-50%,此外,AVF失败是血液透析患者发病和死亡的主要原因。
  
  作者们认为,补充omega-3脂肪酸促成安全地设置AVFs的因素很多:促进血管扩张和红血球灵活性、降低血液黏度和发炎、抑制血小板凝集和平滑肌细胞增殖。
  
  不过,未曾就鱼油或阿斯匹灵对于接受透析患者预防或降低AVF之失败风险予以评估。
  
  麻州波士顿哈佛医学院的Gregory Curfman医师在编辑评论中写道,AVF是动脉和静脉之间直接手术吻合,是一个模型血管系统,在这种特殊形式的血管病理生理疾病中,相对高剂量的鱼油在预防血栓形成或保持通畅方面缺乏效益,这些是负面的资料。
  
  有关饮食补充omega-3脂肪酸(EPA与DHA)对于心血管疾病后之次级预防的诸多临床试验,获得的结果互相矛盾。
  
  开放卷标、非安慰剂控制研究显示,曾发生心肌梗塞的患者中,心血管事件减少15% (GISSI, Prevenzione Study, 1999),高胆固醇血症患者中,严重冠状血管事件减少19% (Japan Eicosapentanoic Acid Lipid Intervention Study, 2007)。另外,随机双盲、GISSI Heart Failure Study (2008)研究指出,曾发生心衰竭且接受omega-3脂肪酸补充品的患者,整体死亡率降低9%。
  
  不过,最近的双盲评估指出,补充omega-3脂肪酸之后,对于心血管疾病的次级预防没有好处,一篇纳入超过20,000名患者的统合分析确认,缺乏好处。
  
  在目前这篇「Omega-3 Fatty Acids (Fish Oils) and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) 」研究中,Irish医师等人着手评估每天4 g鱼油用于第4或5期慢性肾病患者于血液透析前建立AVFs时,降低失败率的效果。
  
  这篇随机双盲安慰剂控制试验,纳入英国、新西兰、马来西亚、澳洲、35处血液透析中心,2008- 2014年间的567名成年患者,纳入最后分析的患者有536人。
  
  最初,患者仅在12周时予以评估AVF中的早期血栓形成,但是研究者扩大为「建立廔管后12个月的AVF失败」,其中还包括了放弃和/或管路设置失败的分析。鱼油的效果是主要目标,阿斯匹灵的效果是次要目标。
  
  随机指定使用鱼油的270名研究对象中,128人(47%)发生AVF失败,安慰剂组的266人中有125人(47%)失败(校正使用阿斯匹灵的相对风险 [RR]为1.03; P = .78)。
  
  特定事件分析获得类似的结果:血栓形成(60 [22%] vs 61 [23%]; 校正RR, 0.98; P = .90)、放弃AVF(51 [19%] vs 58 [22%]; RR, 0.87; P = .43)、管路设置失败(108 [40%] vs 104 [39%]; RR, 1.03; P = .81)。
  
  不过,在患有糖尿病的患者中,鱼油对AVF失败的影响达到显著差异(相互影响P值 = .03; RR, 1.30 vs 0.85)。
  
  使用阿斯匹灵的结果与鱼油类似;也就是说,没有明显的效果。阿斯匹灵组与安慰剂组的AVF失败风险分别是 87 (45%) vs 83 (43%; RR, 1.05; P = .68)。
  
  研究结果发现,对于AVF失败而言,相较于安慰剂组,阿斯匹灵并未产生效益(血栓形成:38 [20%] vs 35 [18%]; RR, 1.09; P = .70)、放弃AVF(46 [24%] vs 35 [18%]; RR, 1.31; P = .17)、管路设置失败(73 [38%] vs 74 [38%]; RR, 0.99; P = .92)。
  
  研究者结论指出,未能证明鱼油对AVF失败有临床相关影响。
  
  研究者指出,研究限制之一是,补充鱼油时间太短(3个月),而他们选这时间点是因为AVFs通常在短时间内就达到成熟或失败。他们认为,使用的阿斯匹灵剂量可能太低。
  
  不过,他们提醒,该研究并未发现缺乏效果的机转。
  
  另外,他们观察到,高失败率仍然是成功血液透析的最重要障碍,并且,被患者和医生认为是首要关键。
  
  资料来源: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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