Interventions for preventing venous thromboembolism in adults undergoing knee arthroscopy.

Knee arthroscopy (KA) is a routine orthopedic procedure recommended to repair cruciate ligaments and meniscus injuries and in eligible patients, to assist the diagnosis of persistent knee pain. KA is associated with a small risk of thromboembolic events. This systematic review aims to assess if pharmacological or non-pharmacological interventions may reduce this risk. This review is the second update of the review first published in 2007. To assess the efficacy and safety of interventions, whether mechanical, pharmacological, or in combination, for thromboprophylaxis in adult patients undergoing KA. For this update, the Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, the CENTRAL, MEDLINE, Embase and CINAHL databases, and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registries, on 14 August 2019. We included randomized controlled trials (RCTs) and controlled clinical trials (CCTs), whether blinded or not, of all types of interventions used to prevent deep vein thrombosis (DVT) in males and females aged 18 years and older undergoing KA. There were no restrictions on language or publication status. Two authors independently selected studies for inclusion, assessed trial quality with the Cochrane 'Risk of bias' tool, and extracted data. A third author addressed discrepancies. We contacted study authors for additional information when required. We used GRADE to assess the certainty of the evidence. This update adds four new studies, bringing the total of included studies to eight and involving 3818 adult participants with no history of thromboembolic disease undergoing KA. Studies compared daily subcutaneous (sc) low-molecular-weight heparin (LMWH) versus control (five studies); oral rivaroxaban 10 mg versus placebo (one study); daily sc LMWH versus graduated compression stockings (GCS) (one study); and aspirin versus control (one study). The incidence of pulmonary embolism (PE) in all trials combined was low, with seven cases in 3818 participants.There were no deaths in any of the intervention or control groups. LMWH versus control When compared with control, LMWH probably results in little to no difference in the incidence of PE in patients undergoing KA (risk ratio (RR) 1.81, 95% confidence interval (CI) 0.49 to 6.65; 1820 participants; 3 studies; moderate-certainty evidence). LMWH showed no reduction of the incidence of symptomatic DVT (RR 0.61, 95% CI 0.18 to 2.03; 1848 participants; 4 studies; moderate-certainty evidence). LMWH may reduce the risk of asymptomatic DVT but the evidence is very uncertain (RR 0.14, 95% CI 0.03 to 0.61; 369 participants; 2 studies; very low-certainty evidence). There was no evidence of an increased risk of all adverse events combined (RR 1.85, 95% CI 0.95 to 3.59; 1978 participants; 5 studies; moderate-certainty evidence). No evidence of a clear effect on major bleeding (RR 0.98, 95% CI 0.06 to 15.72; 1451 participants; 1 study; moderate-certainty evidence), or minor bleeding was observed (RR 1.79, 95% CI 0.84 to 3.84; 1978 participants; 5 studies; moderate-certainty evidence). Rivaroxaban versus placebo One study with 234 participants compared oral rivaroxaban 10 mg versus placebo. No evidence of a clear impact on the risk of PE (no events in either group), symptomatic DVT (RR 0.16, 95% CI 0.02 to 1.29; moderate-certainty evidence); or asymptomatic DVT (RR 0.95, 95% CI 0.06 to 15.01; very low-certainty evidence) was detected. Only bleeding adverse events were reported. No major bleeds occurred in either group and there was no evidence of differences in minor bleeding between the groups (RR 0.63, 95% CI 0.18 to 2.19; moderate-certainty evidence). Aspirin versus control One study compared aspirin with control. No PE, DVT or asymptomatic events were detected in either group. Adverse events including pain and swelling were reported but it was not clear what groups these were in. No bleeds were reported. LMWH versus GCS One study with 1317 participants compared the use of LMWH versus GCS. There was no clear difference in the risk of PE (RR 1.00, 95% CI 0.14 to 7.05; low-certainty evidence). LMWH use did reduce the risk of DVT compared to people using GCS (RR 0.17, 95% CI 0.04 to 0.75; low-certainty evidence). No clear difference in effects was seen between the groups for asymptomatic DVT (RR 0.47, 95% CI 0.21 to 1.09; very low-certainty evidence); major bleeding (RR 3.01, 95% CI 0.61 to 14.88; moderate-certainty evidence) or minor bleeding (RR 1.16, 95% CI 0.64 to 2.08; moderate-certainty evidence). Levels of thromboembolic events were higher in the GCS group than in any other group. We downgraded the certainty of the evidence for imprecision resulting from overall small event numbers; risk of bias due to concerns about lack of blinding, and indirectness as we were uncertain about the direct clinical relevance of asymptomatic DVT detection. There is a small risk that healthy adult patients undergoing KA will develop venous thromboembolism (PE or DVT). There is moderate- to low-certainty evidence of no benefit from the use of LMWH, aspirin or rivaroxaban in reducing this small risk of PE or symptomatic DVT. There is very low-certainty evidence that LMWH use may reduce the risk of asymptomatic DVT when compared to no treatment but it is uncertain how this directly relates to incidence of DVT or PE in healthy patients. No evidence of differences in adverse events (including major and minor bleeding) was seen, but data relating to this were limited due to low numbers of events in the studies reporting within the comparisons.

Perrotta C ，Chahla J ，Badariotti G ，Ramos J ... -  《Cochrane Database of Systematic Reviews》

Interventions for preventing venous thromboembolism in adults undergoing knee arthroscopy.

Knee arthroscopy (KA) is a routine orthopedic procedure recommended to repair cruciate ligaments and meniscus injuries and, in suitable cases, to assist the diagnosis of persistent knee pain. There is a small risk of thromboembolic events associated with KA. This systematic review aims to assess if pharmacological or non-pharmacological interventions may reduce this risk. This is an update of an earlier Cochrane Review. To evaluate the efficacy and safety of interventions - whether mechanical, pharmacological, or a combination of both - for thromboprophylaxis in adults undergoing KA. We used standard, extensive Cochrane search methods. The latest search date was 1 June 2021. We included randomized controlled trials (RCTs) and controlled clinical trials (CCTs), blinded or unblinded, of all types of interventions used to prevent deep vein thrombosis (DVT) in men and women aged 18 years and older undergoing KA. We used standard Cochrane methods. Our primary outcomes were pulmonary embolism (PE), symptomatic DVT, asymptomatic DVT, and all-cause mortality. Our secondary outcomes were adverse effects, major bleeding, and minor bleeding. We used GRADE criteria to assess the certainty of the evidence. We did not identify any new studies for this update. This review includes eight studies involving 3818 adults with no history of thromboembolic disease. Five studies compared daily subcutaneous low-molecular-weight heparin (LMWH) versus no prophylaxis; one study compared oral rivaroxaban 10 mg versus placebo; one study compared daily subcutaneous LMWH versus graduated compression stockings; and one study compared aspirin versus no prophylaxis. The incidence of PE in all studies combined was low, with seven cases in 3818 participants. There were no deaths in any of the intervention or control groups. Low-molecular-weight heparin versus no prophylaxis When compared with no prophylaxis, LMWH probably results in little to no difference in the incidence of PE in people undergoing KA (risk ratio [RR] 1.81, 95% confidence interval [CI] 0.49 to 6.65; 3 studies, 1820 participants; moderate-certainty evidence). LMWH may make little or no difference to the incidence of symptomatic DVT (RR 0.61, 95% CI 0.18 to 2.03; 4 studies, 1848 participants; low-certainty evidence). It is uncertain whether LMWH reduces the risk of asymptomatic DVT (RR 0.14, 95% CI 0.03 to 0.61; 2 studies, 369 participants; very low-certainty evidence). LMWH probably makes little or no difference to the risk of all adverse effects combined (RR 1.85, 95% CI 0.95 to 3.59; 5 studies, 1978 participants; moderate-certainty evidence), major bleeding (RR 0.98, 95% CI 0.06 to 15.72; 1451 participants; moderate-certainty evidence), or minor bleeding (RR 1.79, 95% CI 0.84 to 3.84; 5 studies, 1978 participants; moderate-certainty evidence). Rivaroxaban versus placebo One study with 234 participants compared oral rivaroxaban 10 mg versus placebo. There were no cases of PE reported. Rivaroxaban probably led to little or no difference in symptomatic DVT (RR 0.16, 95% CI 0.02 to 1.29; moderate-certainty evidence). It is uncertain whether rivaroxaban reduces the risk of asymptomatic DVT because the certainty of the evidence is very low (RR 0.95, 95% CI 0.06 to 15.01). The study only reported bleeding adverse effects. No major bleeds occurred in either group, and rivaroxaban probably made little or no difference to minor bleeding (RR 0.63, 95% CI 0.18 to 2.19; moderate-certainty evidence). Aspirin versus no prophylaxis One study compared aspirin with no prophylaxis. There were no PE, DVT or asymptomatic events detected in either group. The study authors reported adverse effects including pain and swelling, but without clarifying which groups these occurred in. There were no bleeds reported. Low-molecular-weight heparin versus compression stockings One study with 1317 participants compared LMWH versus compression stockings. LMWH may lead to little or no difference in the risk of PE compared to compression stockings (RR 1.00, 95% CI 0.14 to 7.05; low-certainty evidence), but it may reduce the risk of symptomatic DVT (RR 0.17, 95% CI 0.04 to 0.75; low-certainty evidence). It is uncertain whether LMWH has any effect on asymptomatic DVT (RR 0.47, 95% CI 0.21 to 1.09; very low-certainty evidence). The results suggest LMWH probably leads to little or no difference in major bleeding (RR 3.01, 95% CI 0.61 to 14.88; moderate-certainty evidence), or minor bleeding (RR 1.16, 95% CI 0.64 to 2.08; moderate-certainty evidence). We downgraded the certainty of the evidence for imprecision due to overall small event numbers, for risk of bias due to concerns about lack of blinding, and for indirectness due to uncertainty about the direct clinical relevance of asymptomatic DVT detection. There is a small risk that healthy adults undergoing KA will develop venous thromboembolism (PE or DVT). We found moderate- to low-certainty evidence of little or no benefit from LMWH, or rivaroxaban in reducing this small risk of PE or symptomatic DVT. The studies provided very low-certainty evidence that LMWH may reduce the risk of asymptomatic DVT compared to no prophylaxis, but it is uncertain how this directly relates to incidence of DVT or PE in healthy people undergoing KA. There is probably little or no difference in adverse effects (including major and minor bleeding), but data relating to these outcomes were limited by low numbers of events in the studies reporting these outcomes.

Perrotta C ，Chahla J ，Badariotti G ，Ramos J ... -  《Cochrane Database of Systematic Reviews》

Primary prophylaxis for venous thromboembolism in ambulatory cancer patients receiving chemotherapy.

Venous thromboembolism (VTE) often complicates the clinical course of cancer. The risk is further increased by chemotherapy, but the trade-off between safety and efficacy of primary thromboprophylaxis in cancer patients treated with chemotherapy is uncertain. This is the third update of a review first published in February 2012. To assess the efficacy and safety of primary thromboprophylaxis for VTE in ambulatory cancer patients receiving chemotherapy compared with placebo or no thromboprophylaxis, or an active control intervention. For this update, the Cochrane Vascular Information Specialist searched the Cochrane Vascular, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 3 August 2020. We also searched the reference lists of identified studies and contacted content experts and trialists for relevant references. Randomised controlled trials comparing any oral or parenteral anticoagulant or mechanical intervention to no thromboprophylaxis or placebo, or comparing two different anticoagulants. We extracted data on risk of bias, participant characteristics, interventions, and outcomes including symptomatic VTE and major bleeding as the primary effectiveness and safety outcomes, respectively. We applied GRADE to assess the certainty of evidence. We identified six additional randomised controlled trials (3326 participants) for this update, bringing the included study total to 32 (15,678 participants), all evaluating pharmacological interventions and performed mainly in people with locally advanced or metastatic cancer. The certainty of the evidence ranged from high to very low across the different outcomes and comparisons. The main limiting factors were imprecision and risk of bias. Thromboprophylaxis with direct oral anticoagulants (direct factor Xa inhibitors apixaban and rivaroxaban) may decrease the incidence of symptomatic VTE (risk ratio (RR) 0.43, 95% confidence interval (CI) 0.18 to 1.06; 3 studies, 1526 participants; low-certainty evidence); and probably increases the risk of major bleeding compared with placebo (RR 1.74, 95% CI 0.82 to 3.68; 3 studies, 1494 participants; moderate-certainty evidence). When compared with no thromboprophylaxis, low-molecular-weight heparin (LMWH) reduced the incidence of symptomatic VTE (RR 0.62, 95% CI 0.46 to 0.83; 11 studies, 3931 participants; high-certainty evidence); and probably increased the risk of major bleeding events (RR 1.63, 95% CI 1.12 to 2.35; 15 studies, 7282 participants; moderate-certainty evidence). In participants with multiple myeloma, LMWH resulted in lower symptomatic VTE compared with the vitamin K antagonist warfarin (RR 0.33, 95% CI 0.14 to 0.83; 1 study, 439 participants; high-certainty evidence), while LMWH probably lowers symptomatic VTE more than aspirin (RR 0.51, 95% CI 0.22 to 1.17; 2 studies, 781 participants; moderate-certainty evidence). Major bleeding was observed in none of the participants with multiple myeloma treated with LMWH or warfarin and in less than 1% of those treated with aspirin. Only one study evaluated unfractionated heparin against no thromboprophylaxis, but did not report on VTE or major bleeding. When compared with placebo or no thromboprophylaxis, warfarin may importantly reduce symptomatic VTE (RR 0.15, 95% CI 0.02 to 1.20; 1 study, 311 participants; low-certainty evidence) and may result in a large increase in major bleeding (RR 3.82, 95% CI 0.97 to 15.04; 4 studies, 994 participants; low-certainty evidence). One study evaluated antithrombin versus no antithrombin in children. This study did not report on symptomatic VTE but did report any VTE (symptomatic and incidental VTE). The effect of antithrombin on any VTE and major bleeding is uncertain (any VTE: RR 0.84, 95% CI 0.41 to 1.73; major bleeding: RR 0.78, 95% CI 0.03 to 18.57; 1 study, 85 participants; very low-certainty evidence). In ambulatory cancer patients, primary thromboprophylaxis with direct factor Xa inhibitors may reduce the incidence of symptomatic VTE (low-certainty evidence) and probably increases the risk of major bleeding (moderate-certainty evidence) when compared with placebo. LMWH decreases the incidence of symptomatic VTE (high-certainty evidence), but increases the risk of major bleeding (moderate-certainty evidence) when compared with placebo or no thromboprophylaxis. Evidence for the use of thromboprophylaxis with anticoagulants other than direct factor Xa inhibitors and LMWH is limited. More studies are warranted to evaluate the efficacy and safety of primary prophylaxis in specific types of chemotherapeutic agents and types of cancer, such as gastrointestinal or genitourinary cancer.

Rutjes AW ，Porreca E ，Candeloro M ，Valeriani E ，Di Nisio M ... -  《Cochrane Database of Systematic Reviews》

Venous thromboembolism prophylaxis for women at risk during pregnancy and the early postnatal period.

Venous thromboembolism (VTE), although rare, is a major cause of maternal mortality and morbidity. Some women are at increased risk of VTE during pregnancy and the early postnatal period (e.g. caesarean section, family history of VTE, or thrombophilia), and so prophylaxis may be considered. As some methods of prophylaxis carry risks of adverse effects, and risk of VTE is often low, benefits of thromboprophylaxis may be outweighed by harms. To assess the effects of thromboprophylaxis during pregnancy and the early postnatal period on the risk of venous thromboembolic disease and adverse effects in women at increased risk of VTE. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (18 October 2019). In addition, we searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for unpublished, planned and ongoing trial reports (18 October 2019). Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, or two (or more) methods of thromboprophylaxis. At least two review authors assessed trial eligibility, extracted data, assessed risk of bias, and judged certainty of evidence for selected critical outcomes (using GRADE). We conducted fixed-effect meta-analysis and reported data (all dichotomous) as summary risk ratios (RRs) with 95% confidence intervals (CIs). Twenty-nine trials (involving 3839 women), overall at moderate to high risk of bias were included. Trials were conducted across the antenatal, peripartum and postnatal periods, with most in high-income countries. Interventions included types and regimens of heparin (low molecular weight heparin (LMWH) and unfractionated heparin (UFH)), hydroxyethyl starch (HES), and compression stockings or devices. Data were limited due to a small number of trials in comparisons and/or few or no events reported. All critical outcomes (assessed for comparisons of heparin versus no treatment/placebo, and LMWH versus UFH) were considered to have very low-certainty evidence, downgraded mainly for study limitations and imprecise effect estimates.  Maternal death was not reported in most studies. Antenatal (± postnatal) prophylaxis For the primary outcomes symptomatic thromboembolic events pulmonary embolism (PE) and/or deep vein thrombosis (DVT), and the critical outcome of adverse effects sufficient to stop treatment, the evidence was very uncertain.  Symptomatic thromboembolic events: - heparin versus no treatment/placebo (RR 0.39; 95% CI 0.08 to 1.98; 4 trials, 476 women; very low-certainty evidence); - LMWH versus UFH (RR 0.47; 95% CI 0.09 to 2.49; 4 trials, 404 women; very low-certainty evidence); Symptomatic PE: - heparin versus no treatment/placebo (RR 0.33; 95% CI 0.02 to 7.14; 3 trials, 187 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 287 women); Symptomatic DVT: - heparin versus no treatment/placebo (RR 0.33; 95% CI 0.04 to 3.10; 4 trials, 227 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 287 women); Adverse effects sufficient to stop treatment: - heparin versus no treatment/placebo (RR 0.49; 95% CI 0.05 to 5.31; 1 trial, 139 women; very low-certainty evidence); - LMWH versus UFH (RR 0.07; 95% CI 0.01 to 0.54; 2 trials, 226 women; very low-certainty evidence). Peripartum/postnatal prophylaxis Vaginal or caesarean birth When UFH and no treatment were compared, the effects on symptomatic thromboembolic events (RR 0.16; 95% CI 0.02 to 1.36; 1 trial, 210 women; very low-certainty evidence), symptomatic PE (RR 0.16; 95% CI 0.01 to 3.34; 1 trial, 210 women; very low-certainty evidence), and symptomatic DVT  (RR 0.27; 95% CI 0.03 to 2.55; 1 trial, 210 women; very low-certainty evidence) were very uncertain.  Maternal death and adverse effects sufficient to stop treatment were not reported. Caesarean birth Symptomatic thromboembolic events: - heparin versus no treatment/placebo (RR 1.30; 95% CI 0.39 to 4.27; 4 trials, 840 women; very low-certainty evidence); - LMWH versus UFH (RR 0.33; 95% CI 0.01 to 7.99; 3 trials, 217 women; very low-certainty evidence); Symptomatic PE: - heparin versus no treatment/placebo (RR 1.10; 95% CI 0.25 to 4.87; 4 trials, 840 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 217 women);  Symptomatic DVT: - heparin versus no treatment/placebo (RR 1.30; 95% CI 0.24 to 6.94; 5 trials, 1140 women; very low-certainty evidence); LMWH versus UFH (RR 0.33; 95% CI 0.01 to 7.99; 3 trials, 217 women; very low-certainty evidence); Maternal death: - heparin versus placebo (no events, 1 trial, 300 women); Adverse effects sufficient to stop treatment: - heparin versus placebo (no events;  1 trial, 140 women). Postnatal prophylaxis No events were reported for LMWH versus no treatment/placebo for: symptomatic thromboembolic events, symptomatic PE and symptomatic DVT (all 2 trials, 58 women), or maternal death (1 trial, 24 women). Adverse effects sufficient to stop treatment were not reported. We were unable to conduct subgroup analyses due to lack of data. Sensitivity analysis including the nine studies at low risk of bias did not impact overall findings. The evidence is very uncertain about benefits and harms of VTE thromboprophylaxis in women during pregnancy and the early postnatal period at increased risk of VTE. Further high-quality very large-scale randomised trials are needed to determine effects of currently used treatments in women with different VTE risk factors. As sufficiently large definitive trials are unlikely to be funded, secondary data analyses based on high-quality registry data are important.

Middleton P ，Shepherd E ，Gomersall JC 《Cochrane Database of Systematic Reviews》

Antiplatelet agents for the treatment of deep venous thrombosis.

Antiplatelet agents may be useful for the treatment of deep venous thrombosis (DVT) when used in addition to best medical practice (BMP), which includes anticoagulation, compression stockings, and clinical care such as physical exercise, skin hydration, etc. Antiplatelet agents could minimise complications such as post-thrombotic syndrome (PTS) and pulmonary embolism (PE). They may also reduce the recurrence of the disease (recurrent venous thromboembolism (recurrent VTE)). However, antiplatelet agents may increase the likelihood of bleeding events. To assess the effects of antiplatelet agents in addition to current BMP compared to current BMP (with or without placebo) for the treatment of DVT. The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 7 December 2021. The review authors searched LILACS and IBECS databases (15 December 2021) and also checked the bibliographies of included trials for further references to relevant trials, and contacted specialists in the field, manufacturers and authors of the included trials. We considered randomised controlled trials (RCTs) examining antiplatelet agents compared to BMP following initial standard anticoagulation treatment for DVT. We included studies where antiplatelet agents were given in addition to current BMP compared to current BMP (with or without placebo) for the treatment of DVT (acute: treatment started within 21 days of symptom onset; chronic: treatment started after 21 days of symptom onset). We evaluated only RCTs where the antiplatelet agents were the unique difference between the groups (intervention and control). We used standard Cochrane methodological procedures. Two review authors independently extracted data and assessed risk of bias of the trials. Any disagreements were resolved by discussion with a third review author. We calculated outcome effects using risk ratio (RR) or mean difference (MD) with a 95% confidence interval (CI) and the number needed to treat to benefit (NNTB). We included six studies with 1625 eligible participants, with data up to 37.2 months of follow-up. For one preplanned comparison (i.e. antiplatelet agents plus BMP versus BMP plus placebo) for acute DVT we identified no eligible studies for inclusion. In acute DVT, antiplatelet agents plus BMP versus BMP alone was assessed by one study (500 participants), which reported on four outcomes until 6 months of follow-up. There were no deaths and no cases of major bleeding reported. The participants who received antiplatelet agents showed a lower risk of PTS (RR 0.74, 95% CI 0.61 to 0.91; 1 study, 500 participants; very low-certainty evidence). The control group presented a lower risk of adverse events compared to the intervention group (RR 2.88, 95% CI 1.06 to 7.80; 1 study, 500 participants; very low-certainty evidence). This study did not provide information for recurrent VTE or PE. In chronic DVT, antiplatelet agents plus BMP versus BMP alone was assessed by one study (224 participants). The study authors reported four relevant outcomes, three of which (major bleeding, mortality and adverse events) showed no events during the 3 years of follow-up. Therefore, an effect estimate could only be reported for recurrent VTE, favouring antiplatelet agents plus BMP versus BMP alone (RR 0.12, 95% CI 0.05 to 0.34; 1 study, 224 participants; very low-certainty evidence). For the outcomes PE and PTS, this study did not present information which could be used for analysis. In chronic DVT, antiplatelet agents plus BMP versus BMP plus placebo was assessed by four studies (901 participants). The meta-analysis of this pooled data showed a lower risk of recurrent VTE for the antiplatelet agents group (RR 0.65, 95%, CI 0.43 to 0.96; NNTB = 14; low-certainty evidence). For major bleeding, we found no clear difference between placebo and intervention groups until 37.2 months of follow-up (RR 0.98, 95% CI 0.29 to 3.34; 1 study, 583 participants; moderate-certainty evidence). In PE fatal/non-fatal outcome, we found no clear difference with the use of antiplatelet agents (RR 0.52, 95% CI 0.23 to 1.14; 1 study, 583 participants; moderate-certainty evidence). For all-cause mortality, the overall effect of antiplatelet agents did not differ from the placebo group (RR 0.48, 95% CI 0.21 to 1.06; 3 studies, 649 participants; moderate-certainty evidence). The adverse events outcome did not show a clear difference (RR 1.57, 95% CI 0.34 to 7.19; 2 studies, 621 participants; moderate-certainty evidence). There is no assessment of PTS in these studies. We downgraded the certainty of evidence for risk of bias, indirectness, imprecision and publication bias. In chronic DVT settings, following the initial standard treatment with anticoagulants, there is low-certainty evidence that antiplatelet agents in addition to BMP may reduce recurrent VTE, (NNTB = 14) when compared to BMP plus placebo. Moderate-certainty evidence shows no clear difference in adverse events, major bleeding and PE when antiplatelet agents are used in addition to BMP compared to BMP plus placebo. In acute and chronic DVT settings, following the initial standard treatment with anticoagulants, we can draw no conclusions for antiplatelet agents in addition to BMP compared to BMP alone due to very low-certainty evidence.  Trials of high methodological quality, that are large and of sufficient duration to detect significant clinical outcomes are needed. Trials should ideally last more than 4 years in order to estimate the long-term effect of antiplatelet agents. Trials should include people with acute and chronic DVT and provide relevant individual data, such as the outcome for each index event (DVT or PE), the use of an inferior vena cava (IVC) filter, whether the DVT is provoked or unprovoked, and the age of participants.

Flumignan CD ，Nakano LC ，Baptista-Silva JC ，Flumignan RL ... -  《Cochrane Database of Systematic Reviews》