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Systematic review

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Journal The Cochrane database of systematic reviews
Year 2022
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Background: It is generally assumed by practitioners and guideline authors that combined modalities (methods of treatment) are more effective than single modalities in preventing venous thromboembolism (VTE), defined as deep vein thrombosis (DVT) or pulmonary embolism (PE), or both. This is the second update of the review first published in 2008. Objectives: The aim of this review was to assess the efficacy of combined intermittent pneumatic leg compression (IPC) and pharmacological prophylaxis compared to single modalities in preventing VTE. Search methods: The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and AMED databases, and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 18 January 2021. We searched the reference lists of relevant articles for additional studies. Selection criteria: We included randomised controlled trials (RCTs) or controlled clinical trials (CCTs) of combined IPC and pharmacological interventions used to prevent VTE compared to either intervention individually. Data collection and analysis: We independently selected studies, applied Cochrane's risk of bias tool, and extracted data. We resolved disagreements by discussion. We performed fixed-effect model meta-analyses with odds ratios (ORs) and 95% confidence intervals (CIs). We used a random-effects model when there was heterogeneity. We assessed the certainty of the evidence using GRADE. The outcomes of interest were PE, DVT, bleeding and major bleeding. Main results: We included a total of 34 studies involving 14,931 participants, mainly undergoing surgery or admitted with trauma. Twenty-five studies were RCTs (12,672 participants) and nine were CCTs (2259 participants). Overall, the risk of bias was mostly unclear or high. We used GRADE to assess the certainty of the evidence and this was downgraded due to the risk of bias, imprecision or indirectness. The addition of pharmacological prophylaxis to IPC compared with IPC alone reduced the incidence of symptomatic PE from 1.34% (34/2530) in the IPC group to 0.65% (19/2932) in the combined group (OR 0.51, 95% CI 0.29 to 0.91; 19 studies, 5462 participants, low-certainty evidence). The incidence of DVT was 3.81% in the IPC group and 2.03% in the combined group showing a reduced incidence of DVT in favour of the combined group (OR 0.51, 95% CI 0.36 to 0.72; 18 studies, 5394 participants, low-certainty evidence). The addition of pharmacological prophylaxis to IPC, however, increased the risk of any bleeding compared to IPC alone: 0.95% (22/2304) in the IPC group and 5.88% (137/2330) in the combined group (OR 6.02, 95% CI 3.88 to 9.35; 13 studies, 4634 participants, very low-certainty evidence). Major bleeding followed a similar pattern: 0.34% (7/2054) in the IPC group compared to 2.21% (46/2079) in the combined group (OR 5.77, 95% CI 2.81 to 11.83; 12 studies, 4133 participants, very low-certainty evidence). Tests for subgroup differences between orthopaedic and non-orthopaedic surgery participants were not possible for PE incidence as no PE events were reported in the orthopaedic subgroup. No difference was detected between orthopaedic and non-orthopaedic surgery participants for DVT incidence (test for subgroup difference P = 0.19). The use of combined IPC and pharmacological prophylaxis modalities compared with pharmacological prophylaxis alone reduced the incidence of PE from 1.84% (61/3318) in the pharmacological prophylaxis group to 0.91% (31/3419) in the combined group (OR 0.46, 95% CI 0.30 to 0.71; 15 studies, 6737 participants, low-certainty evidence). The incidence of DVT was 9.28% (288/3105) in the pharmacological prophylaxis group and 5.48% (167/3046) in the combined group (OR 0.38, 95% CI 0.21 to 0.70; 17 studies; 6151 participants, high-certainty evidence). Increased bleeding side effects were not observed for IPC when it was added to anticoagulation (any bleeding: OR 0.87, 95% CI 0.56 to 1.35, 6 studies, 1314 participants, very low-certainty evidence; major bleeding: OR 1.21, 95% CI 0.35 to 4.18, 5 studies, 908 participants, very low-certainty evidence). No difference was detected between the orthopaedic and non-orthopaedic surgery participants for PE incidence (test for subgroup difference P = 0.82) or for DVT incidence (test for subgroup difference P = 0.69). Authors' conclusions: Evidence suggests that combining IPC with pharmacological prophylaxis, compared to IPC alone reduces the incidence of both PE and DVT (low-certainty evidence). Combining IPC with pharmacological prophylaxis, compared to pharmacological prophylaxis alone, reduces the incidence of both PE (low-certainty evidence) and DVT (high-certainty evidence). We downgraded due to risk of bias in study methodology and imprecision. Very low-certainty evidence suggests that the addition of pharmacological prophylaxis to IPC increased the risk of bleeding compared to IPC alone, a side effect not observed when IPC is added to pharmacological prophylaxis (very low-certainty evidence), as expected for a physical method of thromboprophylaxis. The certainty of the evidence for bleeding was downgraded to very low due to risk of bias in study methodology, imprecision and indirectness. The results of this update agree with current guideline recommendations, which support the use of combined modalities in hospitalised people (limited to those with trauma or undergoing surgery) at risk of developing VTE. More studies on the role of combined modalities in VTE prevention are needed to provide evidence for specific patient groups and to increase our certainty in the evidence. Copyright © 2022 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Systematic review

Unclassified

Auteurs Sun G , Wu J , Wang Q , Liang Q , Jia J , Cheng K , Sun G , Wang Z
Journal The Journal of arthroplasty
Year 2019
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BACKGROUND: The purpose of this study is to perform a meta-analysis to compare outcomes of venous thromboembolism (VTE) prophylaxis with low-molecular-weight heparin (LMWH) vs other anticoagulants in patients who received total knee (TKA) or total hip arthroplasty (THA). METHODS: MEDLINE, Cochrane, EMBASE, and Google Scholar databases were searched until June 30, 2017 for eligible randomized controlled studies. RESULTS: Thirty-two randomized controlled studies were included. LMWH provided better protection against VTE than placebo. In both TKA and THA patients, the rates of VTE were lower with factor Xa inhibitors than LMWH. In THA patients, the rate of deep vein thrombosis (DVT) was lower with factor Xa inhibitors than LMWH. In TKA patients, the rates of VTE and DVT were similar between LMWH and direct thrombin inhibitors. In THA patients, the rate of VTE was lower with direct thrombin inhibitors than with LMWH, while the DVT rates were similar. The pulmonary embolism rates were similar between all 3 classes of drugs in TKA and THR patients, as were the major bleeding rates. Nonmajor and minor bleeding rates were also similar between the 3 drug classes. CONCLUSION: LMWH is associated with a higher rate of VTE than factor Xa inhibitors in TKA and THA patients. Direct thrombin inhibitors are associated with a lower rate of VTE in THA patients, but their effectiveness with respect to DVT and pulmonary embolism prophylaxis is similar to that of LMWH in TKA and THA patients.

Systematic review

Unclassified

Journal Value in health : the journal of the International Society for Pharmacoeconomics and Outcomes Research
Year 2019
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OBJECTIVES: To assess the efficacy and safety of venous thromboembolism prophylaxis in people undergoing elective total hip replacement. METHODS: Systematic review and Bayesian network meta-analyses of randomized controlled trials were conducted for 3 outcomes: deep vein thrombosis (DVT), pulmonary embolism (PE), and major bleeding (MB). MEDLINE, EMBASE, and Cochrane Library (CENTRAL) databases were searched. Study quality was assessed using the Cochrane risk-of-bias checklist. Fixed- and random-effects models were fitted and compared. The median relative risk (RR) and odds ratio (OR) compared with no prophylaxis, with their 95% credible intervals (CrIs), rank, and probability of being the best, were calculated. RESULTS: Forty-two (n = 24 374, 26 interventions), 30 (n = 28 842, 23 interventions), and 24 (n = 31 792, 15 interventions) randomized controlled trials were included in the DVT, PE, and MB networks, respectively. Rivaroxaban had the highest probability of being the most effective intervention for DVT (RR 0.06 [95% CrI 0.01-0.29]). Strategy of low-molecular-weight heparin followed by aspirin had the highest probability of reducing the risk of PE and MB (RR 0.0011 [95% CrI 0.00-0.096] and OR 0.37 [95% CrI 0.00-26.96], respectively). The ranking of efficacy estimates across the 3 networks, particularly PE and MB, had very wide CrIs, indicating high degree of uncertainty. CONCLUSIONS: A strategy of low-molecular-weight heparin given for 10 days followed by aspirin for 28 days had the best benefit-risk balance, with the highest probability of being the best on the basis of the results of the PE and MB network meta-analyses. Nevertheless, there is considerable uncertainty around the median ranks of the interventions.

Systematic review

Unclassified

Auteurs Kerr DL , Butler S , Read AC , Harris IA
Journal ANZ journal of surgery
Year 2019
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BACKGROUND: Currently there is significant variation in the management of venous thromboembolism prophylaxis following total knee arthroplasty (TKA). Excessive wound ooze and bleeding is thought to increase a patient's risk of haematoma formation and possible infection. We evaluated the rate of unexpected reoperation in the perioperative period in patients who received aspirin, rivaroxaban or enoxaparin following primary TKA. METHOD: A systematic literature search was conducted in MEDLINE, CENTRAL and Embase to identify patients who underwent primary TKA. Two researchers independently reviewed the references identified in the literature search. The final 11 studies included for review were published between 1996 and 2016. RESULTS: There was a higher rate of reoperation in patients treated with aspirin following TKA when compared to enoxaparin and rivaroxaban in the perioperative period. Of the 5141 patients treated with enoxaparin, 11 (0.21%) required reoperation; of the 2764 patients treated with rivaroxaban, 12 (0.43%) required reoperation; and of the 228 patients treated with aspirin, seven (3.07%) required reoperation. The average time to follow-up in the 11 studies was 55 days, ranging from 30 to 180 days post-operatively. CONCLUSION: There was a higher rate of reoperation in patients treated with aspirin following TKA when compared to enoxaparin and rivaroxaban in the perioperative period. While there is extensive data on the safety and efficacy of these medications following joint arthroplasty, improved reporting of surgically relevant outcomes are needed to assist both the surgeon and patient in clinical decision-making.

Systematic review

Unclassified

Journal Journal of orthopaedics
Year 2019
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Background: Patients who undergo knee or hip arthroplasty are at a significant risk of venous thromboembolism (VTE) development (pulmonary embolism and/or deep-vein thrombosis). Many different thromboprophylactic strategies have been used for the prevention of VTE in these patients with different outcomes. Therefore, our aim was to evaluate the efficacy and safety of aspirin prophylaxis when compared with placebo or anticoagulants in this population of patients. Methods: A comprehensive electronic database search was conducted for all randomized controlled trials (RCTs) comparing the clinical outcomes of aspirin versus placebo or anticoagulants for the prevention of VTE after knee or hip arthroplasty. The primary outcome was VTE incidence. Secondary outcomes included any bleeding, major bleeding and mortality. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) using a random-effects model at the longest possible follow-up period. Results: We included 13 RCTs with a total of 20,115 patients with a mean age of 67.15 ± 9.54 and 24.39% males. Aspirin was found to be associated with a non-significantly reduced VTE events compared with other thromboprophylactic methods (RR 0.87; 95% CI: 0.61–1.23; P = 0.43). Compared with placebo, aspirin was associated with significant reduction of VTE (RR 0.65; 95% CI: 0.47–0.89; P = 0.008). There were no significant differences in the clinical outcomes between all groups with regard to mortality (RR 0.98; 95% CI: 0.86–1.11; P = 0.72), major bleeding events (RR 0.96; 95% CI: 0.50–1.84; P = 0.91), and any bleeding events (RR: 1.09; 95% CI: 0.82–1.44; P = 0.56). Conclusion: Among patients who underwent knee or hip arthroplasty, aspirin prophylaxis was found to be associated with similar efficacy and safety outcomes when compared with anticoagulants. When compared with placebo, aspirin prophylaxis was associated with significantly reduced VTE and a comparable safety profile.

Systematic review

Unclassified

Auteurs Sachdeva A , Dalton M , Lees T
Journal The Cochrane database of systematic reviews
Year 2018
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BACKGROUND: Hospitalised patients are at increased risk of developing deep vein thrombosis (DVT) in the lower limb and pelvic veins, on a background of prolonged immobilisation associated with their medical or surgical illness. Patients with DVT are at increased risk of developing a pulmonary embolism (PE). The use of graduated compression stockings (GCS) in hospitalised patients has been proposed to decrease the risk of DVT. This is an update of a Cochrane Review first published in 2000, and last updated in 2014. OBJECTIVES: To evaluate the effectiveness and safety of graduated compression stockings in preventing deep vein thrombosis in various groups of hospitalised patients. SEARCH METHODS: For this review the Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), and trials registries on 21 March 2017; and the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE Ovid, Embase Ovid, CINAHL Ebsco, AMED Ovid , and trials registries on 12 June 2018. SELECTION CRITERIA: Randomised controlled trials (RCTs) involving GCS alone, or GCS used on a background of any other DVT prophylactic method. We combined results from both of these groups of trials. DATA COLLECTION AND ANALYSIS: Two review authors (AS, MD) assessed potentially eligible trials for inclusion. One review author (AS) extracted the data, which a second review author (MD) cross-checked and authenticated. Two review authors (AS, MD) assessed the methodological quality of trials with the Cochrane 'Risk of bias' tool. Any disagreements were resolved by discussion with the senior review author (TL). For dichotomous outcomes, we calculated the Peto odds ratio and corresponding 95% confidence interval. We pooled data using a fixed-effect model. We used the GRADE system to evaluate the overall quality of the evidence supporting the outcomes assessed in this review. MAIN RESULTS: We included 20 RCTs involving a total of 1681 individual participants and 1172 individual legs (2853 analytic units). Of these 20 trials, 10 included patients undergoing general surgery; six included patients undergoing orthopaedic surgery; three individual trials included patients undergoing neurosurgery, cardiac surgery, and gynaecological surgery, respectively; and only one trial included medical patients. Graduated compression stockings were applied on the day before surgery or on the day of surgery and were worn up until discharge or until the participants were fully mobile. In the majority of the included studies DVT was identified by the radioactive I125 uptake test. Duration of follow-up ranged from seven to 14 days. The included studies were at an overall low risk of bias.We were able to pool the data from 20 studies reporting the incidence of DVT. In the GCS group, 134 of 1445 units developed DVT (9%) in comparison to the control group (without GCS), in which 290 of 1408 units developed DVT (21%). The Peto odds ratio (OR) was 0.35 (95% confidence interval (CI) 0.28 to 0.43; 20 studies; 2853 units; high-quality evidence), showing an overall effect favouring treatment with GCS (P < 0.001).Based on results from eight included studies, the incidence of proximal DVT was 7 of 517 (1%) units in the GCS group and 28 of 518 (5%) units in the control group. The Peto OR was 0.26 (95% CI 0.13 to 0.53; 8 studies; 1035 units; moderate-quality evidence) with an overall effect favouring treatment with GCS (P < 0.001). Combining results from five studies, all based on surgical patients, the incidence of PE was 5 of 283 (2%) participants in the GCS group and 14 of 286 (5%) in the control group. The Peto OR was 0.38 (95% CI 0.15 to 0.96; 5 studies; 569 participants; low-quality evidence) with an overall effect favouring treatment with GCS (P = 0.04). We downgraded the quality of the evidence for proximal DVT and PE due to low event rate (imprecision) and lack of routine screening for PE (inconsistency).We carried out subgroup analysis by speciality (surgical or medical patients). Combining results from 19 trials focusing on surgical patients, 134 of 1365 (9.8%) units developed DVT in the GCS group compared to 282 of 1328 (21.2%) units in the control group. The Peto OR was 0.35 (95% CI 0.28 to 0.44; high-quality evidence), with an overall effect favouring treatment with GCS (P < 0.001). Based on results from seven included studies, the incidence of proximal DVT was 7 of 437 units (1.6%) in the GCS group and 28 of 438 (6.4%) in the control group. The Peto OR was 0.26 (95% CI 0.13 to 0.53; 875 units; moderate-quality evidence) with an overall effect favouring treatment with GCS (P < 0.001). We downgraded the evidence for proximal DVT due to low event rate (imprecision).Based on the results from one trial focusing on medical patients admitted following acute myocardial infarction, 0 of 80 (0%) legs developed DVT in the GCS group and 8 of 80 (10%) legs developed DVT in the control group. The Peto OR was 0.12 (95% CI 0.03 to 0.51; low-quality evidence) with an overall effect favouring treatment with GCS (P = 0.004). None of the medical patients in either group developed a proximal DVT, and the incidence of PE was not reported.Limited data were available to accurately assess the incidence of adverse effects and complications with the use of GCS as these were not routinely quantitatively reported in the included studies. AUTHORS' CONCLUSIONS: There is high-quality evidence that GCS are effective in reducing the risk of DVT in hospitalised patients who have undergone general and orthopaedic surgery, with or without other methods of background thromboprophylaxis, where clinically appropriate. There is moderate-quality evidence that GCS probably reduce the risk of proximal DVT, and low-quality evidence that GCS may reduce the risk of PE. However, there remains a paucity of evidence to assess the effectiveness of GCS in diminishing the risk of DVT in medical patients.

Systematic review

Unclassified

Auteurs Lu X , Lin J
Journal BMC musculoskeletal disorders
Year 2018
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BACKGROUND: Venous thromboembolism (VTE) is an important complication following total hip replacement (THR) and total knee replacement (TKR) surgeries. Aim of this study was to comprehensively compare the clinical outcomes of low-molecular-weight heparin (LMWH) with other anticoagulants in patients who underwent TKR or THR surgery. METHODS: Medline, Cochrane, EMBASE, and Google Scholar databases were searched for eligible randomized controlled studies (RCTs) published before June 30, 2017. Meta-analyses of odds ratios were performed along with subgroup and sensitivity analyses. RESULTS: Twenty-one RCTs were included. In comparison with placebo, LMWH treatment was associated with a lower risk of VTE and deep vein thrombosis (DVT) (P values < 0.001) but similar risk of pulmonary embolism (PE) (P = 0.227) in THR subjects. Compared to factor Xa inhibitors, LMWH treatment was associated with higher risk of VTE in TKR subjects (P < 0.001), and higher DVT risk (P < 0.001) but similar risk of PE and major bleeding in both THR and TKR. The risk of either VTE, DVT, PE, or major bleeding was similar between LMWH and direct thrombin inhibitors in both THR and TKR, but major bleeding was lower with LMWH in patients who underwent THR (P = 0.048). CONCLUSION: In comparison with factor Xa inhibitors, LMWH may have higher risk of VTE and DVT, whereas compared to direct thrombin inhibitors, LMWH may have lower risk of major bleeding after THR or TKR.

Systematic review

Unclassified

Journal Journal of Thrombosis and Haemostasis
Year 2017
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ESSENTIALS: Despite trial data, guidelines have not endorsed direct oral Xa inhibitors above other options. We provide profiles of venous thromboembolism and hemorrhage risk for 12 options. Direct oral Xa inhibitors had a favorable profile compared with low-molecular-weight heparin. Other options did not have favorable profiles compared with low-molecular-weight heparin. SUMMARY: BACKGROUND: There are numerous trials and several meta-analyses comparing venous thromboembolism (VTE) prophylaxis options after total hip and knee replacement (THR and TKR). None have included simultaneous comparison of new with older options. Objective To measure simultaneously the relative risk of VTE and hemorrhage for 12 prophylaxis options. METHODS: We abstracted VTE and hemorrhage information from randomized controlled trials published between January 1990 and June 2016 comparing 12 prophylaxis options. We then constructed networks to compute the relative risk for each option, relative to once-daily dosing with low-molecular-weight heparin (LMWH) Low. RESULTS MAIN: Relative to LMWH Low, direct oral Xa inhibitors had the lowest risk of total deep vein thrombosis (DVT)-asymptomatic and symptomatic- (odds ratio [OR], 0.45; 95% confidence interval [CI], 0.35-0.57), translating to 53-139 fewer DVTs per 1000 patients. Vitamin K antagonists (VKAs) titrated to International Normalized Ratio [INR] 2-3 predicted 56% more DVT events (OR, 1.56; 95% CI, 1.14-2.14). Aspirin performed similarly (OR, 0.80; 95% CI, 0.34-1.86), although small numbers prohibit firm conclusions. Direct oral Xa inhibitors did not lead to significantly more bleeding (OR, 1.21; 95% CI, 0.79-1.90). Secondary: Relative to LMWH Low, direct oral Xa inhibitors prevented 4-fold more symptomatic DVTs (OR, 0.25; 95% CI, 0.13-0.47). CONCLUSIONS: Relative to LMWH Low, direct oral Xa inhibitors had a more favorable profile of VTE and hemorrhage risk, whereas VKAs had a less favorable profile. The profile of other agents was not more or less favorable. Clinicians should consider these profiles when selecting prophylaxis options.

Systematic review

Unclassified

Journal Journal of Arthroplasty
Year 2017
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BACKGROUND: Venous thromboembolism causes significant morbidity and mortality in patients after total joint arthroplasty. Although network meta-analyses have demonstrated a benefit of various thromboprophylactic agents, there remains a concern in the surgical community regarding the resulting wound complications. There is currently no systematic review of the surgical site bleeding complications of thromboprophylactic agents. The aim of this study was to systematically review the surgical site bleeding outcomes of venous thromboembolism prophylaxis in this population. METHODS: A systematic review and meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized controlled trials comparing more than one of low-molecular-weight heparin (LMWH), warfarin, rivaroxaban, apixaban, dabigatran, aspirin, or no pharmacologic treatment in patients after total hip or knee arthroplasty were selected for inclusion. Five meta-analyses were performed to compare LMWH with control, warfarin, apixaban, rivaroxaban, and dabigatran. RESULTS: Forty-five randomized controlled trials of 56,730 patients were included. LMWH had a significantly increased relative risk of surgical site bleeding in comparison with control (relative risk, 2.32; 95% confidence interval, 1.40-3.85) and warfarin (1.54; 1.23-1.94). The relative risk of LMWH trended higher than apixaban (1.27; 1.00-1.63) and was similar to rivaroxaban (0.95; 0.74-1.23). Only 1 study reported the risk of surgical site bleeding in LMWH vs dabigatran (5.97; 2.08-17.11). CONCLUSION: LMWH increased the risk of surgical site bleeding compared with control, warfarin. and dabigatran and trended toward an increased risk compared with apixaban. The risk of surgical site bleeding was similar with LMWH and rivaroxaban.

Systematic review

Unclassified

Livre AHRQ Comparative Effectiveness Reviews
Year 2017
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BACKGROUND: Major orthopedic surgeries, such as total knee replacement (TKR), total hip replacement (THR), and hip fracture (HFx) surgery, carry a high risk for venous thromboembolism (VTE)—deep vein thrombosis (DVT) and pulmonary embolism (PE). METHODS: Updating a 2012 review, we compare interventions to prevent VTE after TKR, THR, and HFx surgery. We searched four databases and other sources through June 3, 2016, for randomized controlled trials (RCTs) and large nonrandomized comparative studies (NRCSs) reporting postoperative VTE, major bleeding, and other adverse events. We conducted pairwise meta-analyses, Bayesian network meta-analyses, and strength of evidence (SoE) synthesis. RESULTS: Overall, 127 RCTs and 15 NRCSs met criteria. For THR: low molecular weight heparin (LMWH) has lower risk than unfractionated heparin (UFH) of various VTE outcomes (moderate to high SoE) and major bleeding (moderate SoE). LMWH and aspirin have similar risks of total PE, symptomatic DVT, and major bleeding (low SoE). LMWH has less major bleeding (low SoE) than direct thrombin inhibitors (DTI), but DTI has lower DVT risks (moderate SoE). LMWH has less major bleeding than vitamin K antagonists (VKA) (high SoE). LMWH and factor Xa inhibitor (FXaI) comparisons are inconsistent across VTE outcomes, but LMWH has less major bleeding (high SoE). VKA has lower proximal DVT risk than mechanical devices (high SoE). Longer duration LMWH has lower risk of various VTE outcome risks (low to high SoE). Higher dose LMWH has lower total DVT risk (low SoE) but more major bleeding (moderate SoE). Higher dose FXaI has lower total VTE risk (low SoE). For TKR: LMWH has lower DVT risks than VKA (low to high SoE), but VKA has less major bleeding (low SoE). FXaI has lower risk than LMWH of various VTE outcomes (low to moderate SoE), but LMWH has less major bleeding (low SoE) and more study-defined serious adverse events (low SoE). Higher dose DTI has lower DVT risk (moderate to high SoE) but more major bleeding (low SoE). Higher dose FXaI has lower risk of various VTE outcomes (low to moderate SoE). For HFx surgery: LMWH has lower total DVT risk than FXaI (moderate SoE). CONCLUSIONS: VTE prophylaxis after major orthopedic surgery trades off lowered VTE risk with possible adverse events—in particular, for most interventions, major bleeding. In THR, LMWH has lower VTE and adverse event risks than UFH, LMWH and aspirin have similar risks of VTE and major bleeding, DTI has lower DVT risk than LMWH but higher major bleeding risk, and higher dose LMWH has lower DVT risk but higher major bleeding risk than lower dose. In TKR, VKA has higher DVT risk than LMWH but lower major bleeding risk, and higher dose DTI has lower DVT risk but higher major bleeding risk than lower dose. In HFx surgery and for other intervention comparisons, there is insufficient evidence to assess both benefits and harms, or findings are inconsistent. Importantly, though, most studies evaluate “total DVT” (an outcome of unclear clinical significance since it includes asymptomatic and other low-risk DVTs), but relatively few studies evaluate PE and other clinically important outcomes. This limitation yields a high likelihood of selective outcome reporting bias. There is also relatively sparse evidence on interventions other than LMWH.