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Antiplatelet drugs for polycythaemia vera and essential thrombocythaemia

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Polycythaemia vera and essential thrombocythaemia are chronic Philadelphia-negative myeloproliferative disorders, which increase the risk of arterial and venous thrombosis as well as bleeding. In addition to the different therapeutic strategies available, aspirin is often used to prevent platelet aggregation.


To quantify the benefit and harm of antiplatelet drugs for long-term primary and secondary prophylaxis of arterial and venous thrombotic events in patients with polycythaemia vera or essential thrombocythaemia.

Search methods

Our searched included the CENTRAL (The Cochrane Library, issue 1 2007), MEDLINE (1966 to 2007) and EMBASE (1980 to 2007) databases, online registers of ongoing trials and conference proceedings. The date of the last search was March 2007.

Selection criteria

All randomised controlled trials (RCTs) comparing long-term (>6 months) use of an antiplatelet drug versus placebo or no treatment in patients with polycythaemia vera or essential thrombocythaemia, diagnosed by established international criteria, with data for at least one of the selected outcomes, were included.

Data collection and analysis

Using a predefined extraction form, we collected and analysed the following data where appropriate: mortality from arterial and venous thrombotic events, mortality from bleeding episodes, fatal and non-fatal arterial thrombotic events, fatal and non-fatal venous thrombotic events, micro-circulation events, transient neurological and ocular manifestations, major and minor bleeding episodes, all-cause mortality and any adverse events. We based quantitative analysis of outcome data on an intention-to-treat principle. The overall treatment effect was estimated by the pooled odds ratio (OR) with 95% confidence interval (CI) using a fixed-effect model (Mantel-Haenszel).

Main results

Two RCTs that investigated 630 patients with an established diagnosis of polycythaemia vera, with no clear indication or contraindication to aspirin therapy, were included in this review. The use of aspirin, compared with placebo, was associated with a lower risk of fatal thrombotic events (although this benefit was not statistically significant (OR 0.20, 95% CI 0.03 to 1.14)) and did not increase the risk of major bleeding (OR 0.99, 95% CI 0.23 to 4.36). No studies have been published in patients with essential thrombocythaemia or studying other antiplatelet drugs.

Authors' conclusions

The available evidence suggests that the use of aspirin is associated with a statistically non-significant reduction in the risk of fatal thrombotic events, without an increased risk of major bleeding, when compared with no treatment in patients with polycythaemia vera who have no clear indication or contraindication to aspirin therapy.



抗血小板藥物用於真性多紅血球症(polycythaemia vera)及原發性血小板增多症(essential thrombocythaemia)

真性多紅血球症及原發性血小板增多症屬於費城染色體陰性之慢性骨髓增生性疾病, 這類疾病會增加動脈及靜脈栓塞或是出血的機率. 除了不同的治療用途, 阿司匹林(Aspirin)通常用於防止血小板聚集.


在真性多紅血球症(polycythaemia vera)及原發性血小板增多症的患者, 為了量化抗血小板藥物對於長期、初期及次級預防動脈和靜脈血栓形成的好處及壞處.


我們搜尋了考科藍實證醫學資料庫(CENTRAL, The Cochrane Library, 2007年第1期),醫學文獻資料庫(MEDLINE,1966年至2007年),醫藥學文獻資料庫(EMBASE,1980年至2007年),及網路上登記正在進行的臨床試驗及會議記錄. 最後一次搜索的日期是2007年3月


所有隨機對照試驗(RCTs), 包括比較長期(大於6個月)使用抗血小板藥物與安慰劑, 或不治療的真性多紅血球症或原發性血小板增多症的患者, 診斷是依據國際標準, 其數據至少包含其中一個選定的結果


使用預定義選取表格, 我們收集和分析了以下數據: 動脈和靜脈血栓形成造成的死亡率, 出血造成的死亡率, 致命和非致命動脈血栓形成的事件, 致命和非致命性靜脈血栓形成的事件, 微循環的事件, 暫時性神經系統和眼部症狀, 嚴重及輕微出血事件, 所有原因的死亡率和任何不良反應. 我們根據治療意向(intention to treat, ITT)原則以定量分析其結果. 就整體治療效果使用pooled odds ratio (OR)及其95%可信區間(95% confidence interval, CI)及使用固定效應模型(fixedeffect model, MantelHaenszel法)來進行估計.


兩個隨機對照試驗共研究630例確診為真性多紅血球症的患者, 這些病人在這個研究中均沒有使用阿司匹林治療的明確之適應症及禁忌. 與安慰劑相比, 使用阿司匹林能有一個較低發生致命血栓事件的機率(雖然這個好處之統計上意義是不顯著(OR 0.20, 95%CI為0.03至1.14), 及並沒有增加嚴重出血的機率(OR 0.99, 95%CI為0.23至4.36). 但關於原發性血小板增多症的患者或其他抗血小板藥物,沒有研究發表.


現有的證據顯示, 真性多紅血球症且沒有阿司匹林治療的明確之適應症及禁忌的患者, 使用阿司匹林來降低致命血栓事件的風險, 並避免增加嚴重出血機率, 沒有統計上的意義,



此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。


抗血小板藥物對於真性多紅血球症及原發性血小板增多症的患者, 預防動脈和靜脈血栓形成事件上並不清楚, 在過去, 低劑量阿司匹林作為抗血小板治療的藥物, 在預防心血管事件上是首選, 但使用在骨髓增生性疾病上因有出血的風險而限制了它的使用. 這個研究共收集兩項試驗, 包含630人, 患者均為真性多紅血球症, 且無使用阿司匹林治療的明確之適應症及禁忌. 此研究證據顯示, 低劑量阿司匹林可降低致命血栓事件的風險, 且不會增加嚴重出血的機率. 但關於原發性血小板增多症患者,並沒有研究發表.

Plain language summary

Antiplatelet drugs for preventing arterial and venous thrombotic events in patients with polycythaemia vera or essential thrombocythaemia

Low-dose aspirin as an antiplatelet therapy is the drug of choice for preventing cardiovascular events, but the potential risk of bleeding has limited its use in myeloproliferative disorders in the past. This review of 630 people in two trials found that in patients with polycythaemia vera and with no clear indication or contraindication to aspirin therapy, the trial evidence suggests that low-dose aspirin reduces the risk of fatal thrombotic events, without an increased risk of major bleeding. No studies in patients with essential thrombocythaemia have been published.

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