Extended-duration new oral anticoagulants for venous thromboprophylaxis in patients undergoing total hip arthroplasty: a meta-analysis of the randomized controlled trials

Anticoagulants (extended duration) for prevention of venous thromboembolism following total hip or knee replacement or hip fracture repair

BACKGROUND

The optimal duration of thromboprophylaxis after total hip or knee replacement, or hip fracture repair remains controversial. It is common practice to administer prophylaxis using low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH) until discharge from hospital, usually seven to 14 days after surgery. International guidelines recommend extending thromboprophylaxis for up to 35 days following major orthopaedic surgery but the recommendation is weak due to moderate quality evidence. In addition, recent oral anticoagulants that exert effect by direct inhibition of thrombin or activated factor X lack the need for monitoring and have few known drug interactions. Interest in this topic remains high.

OBJECTIVES

To assess the effects of extended-duration anticoagulant thromboprophylaxis for the prevention of venous thromboembolism (VTE) in people undergoing elective hip or knee replacement surgery, or hip fracture repair.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Specialised Register (last searched May 2015) and CENTRAL (2015, Issue 4). Clinical trials databases were searched for ongoing or unpublished studies.

SELECTION CRITERIA

Randomised controlled trials assessing extended-duration thromboprophylaxis (five to seven weeks) using accepted prophylactic doses of LMWH, UFH, vitamin K antagonists (VKA) or direct oral anticoagulants (DOAC) compared with short-duration thromboprophylaxis (seven to 14 days) followed by placebo, no treatment or similar extended-duration thromboprophylaxis with LMWH, UFH, VKA or DOACs in participants undergoing hip or knee replacement or hip fracture repair.

DATA COLLECTION AND ANALYSIS

We independently selected trials and extracted data. Disagreements were resolved 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.

MAIN RESULTS

We included 16 studies (24,930 participants); six compared heparin with placebo, one compared VKA with placebo, two compared DOAC with placebo, one compared VKA with heparin, five compared DOAC with heparin and one compared anticoagulants chosen at investigators' discretion with placebo. Three trials included participants undergoing knee replacement. No studies assessed hip fracture repair.Trials were generally of good methodological quality. The main reason for unclear risk of bias was insufficient reporting. The quality of evidence according to GRADE was generally moderate, as some comparisons included a single study, low number of events or heterogeneity between studies leading to wide CIs.We showed no difference between extended-duration heparin and placebo in symptomatic VTE (OR 0.59, 95% CI 0.35 to 1.01; 2329 participants; 5 studies; high quality evidence), symptomatic deep vein thrombosis (DVT) (OR 0.73, 95% CI 0.39 to 1.38; 2019 participants; 4 studies; moderate quality evidence), symptomatic pulmonary embolism (PE) (OR 0.61, 95% CI 0.16 to 2.33; 1595 participants; 3 studies; low quality evidence) and major bleeding (OR 0.59, 95% CI 0.14 to 2.46; 2500 participants; 5 studies; moderate quality evidence). Minor bleeding was increased in the heparin group (OR 2.01, 95% CI 1.43 to 2.81; 2500 participants; 5 studies; high quality evidence). Clinically relevant non-major bleeding was not reported.We showed no difference between extended-duration VKA and placebo (one study, 360 participants) for symptomatic VTE (OR 0.10, 95% CI 0.01 to 1.94; moderate quality evidence), symptomatic DVT (OR 0.13, 95% CI 0.01 to 2.62; moderate quality evidence), symptomatic PE (OR 0.32, 95% CI 0.01 to 7.84; moderate quality evidence) and major bleeding (OR 2.89, 95% CI 0.12 to 71.31; low quality evidence). Clinically relevant non-major bleeding and minor bleeding were not reported.Extended-duration DOAC showed reduced symptomatic VTE (OR 0.20, 95% CI 0.06 to 0.68; 2419 participants; 1 study; moderate quality evidence) and symptomatic DVT (OR 0.18, 95% CI 0.04 to 0.81; 2459 participants; 2 studies; high quality evidence) compared to placebo. No differences were found for symptomatic PE (OR 0.25, 95% CI 0.03 to 2.25; 1733 participants; 1 study; low quality evidence), major bleeding (OR 1.00, 95% CI 0.06 to 16.02; 2457 participants; 1 study; low quality evidence), clinically relevant non-major bleeding (OR 1.22, 95% CI 0.76 to 1.95; 2457 participants; 1 study; moderate quality evidence) and minor bleeding (OR 1.18, 95% CI 0.74 to 1.88; 2457 participants; 1 study; moderate quality evidence).We showed no difference between extended-duration anticoagulants chosen at investigators' discretion and placebo (one study, 557 participants, low quality evidence) for symptomatic VTE (OR 0.50, 95% CI 0.09 to 2.74), symptomatic DVT (OR 0.33, 95% CI 0.03 to 3.21), symptomatic PE (OR 1.00, 95% CI 0.06 to 16.13), and major bleeding (OR 5.05, 95% CI 0.24 to 105.76). Clinically relevant non-major bleeding and minor bleeding were not reported.We showed no difference between extended-duration VKA and heparin (one study, low quality evidence) for symptomatic VTE (OR 1.64, 95% CI 0.85 to 3.16; 1279 participants), symptomatic DVT (OR 1.36, 95% CI 0.69 to 2.68; 1279 participants), symptomatic PE (OR 9.16, 95% CI 0.49 to 170.42; 1279 participants), major bleeding (OR 3.87, 95% CI 1.91 to 7.85; 1272 participants) and minor bleeding (OR 1.33, 95% CI 0.64 to 2.76; 1279 participants). Clinically relevant non-major bleeding was not reported.We showed no difference between extended-duration DOAC and heparin for symptomatic VTE (OR 0.70, 95% CI 0.28 to 1.70; 15,977 participants; 5 studies; low quality evidence), symptomatic DVT (OR 0.60, 95% CI 0.11 to 3.27; 15,977 participants; 5 studies; low quality evidence), symptomatic PE (OR 0.91, 95% CI 0.43 to 1.94; 14,731 participants; 5 studies; moderate quality evidence), major bleeding (OR 1.11, 95% CI 0.79 to 1.54; 16,199 participants; 5 studies; high quality evidence), clinically relevant non-major bleeding (OR 1.08, 95% CI 0.90 to 1.28; 15,241 participants; 4 studies; high quality evidence) and minor bleeding (OR 0.95, 95% CI 0.82 to 1.10; 11,766 participants; 4 studies; high quality evidence).

AUTHORS' CONCLUSIONS

Moderate quality evidence suggests extended-duration anticoagulants to prevent VTE should be considered for people undergoing hip replacement surgery, although the benefit should be weighed against the increased risk of minor bleeding. Further studies are needed to better understand the association between VTE and extended-duration oral anticoagulants in relation to knee replacement and hip fracture repair, as well as outcomes such as distal and proximal DVT, reoperation, wound infection and healing.

Risk factors for venous thromboembolism after acute trauma: A population-based case-cohort study

BACKGROUND

Predictors of venous thromboembolism (VTE) after trauma are uncertain.

OBJECTIVE

To identify independent predictors of VTE after acute trauma.

METHODS

Using Rochester Epidemiology Project (REP) resources, we identified all Olmsted County, MN residents with objectively-diagnosed incident VTE within 92days after hospitalization for acute trauma over the 18-year period, 1988-2005. We also identified all Olmsted County residents hospitalized for acute trauma over this time period and chose one to two residents frequency-matched to VTE cases on sex, event year group and ICD-9-CM trauma code predictive of surgery. In a case-cohort study, demographic, baseline and time-dependent characteristics were tested as predictors of VTE after trauma using Cox proportional hazards modeling.

RESULTS

Among 200 incident VTE cases, the median (interquartile range) time from trauma to VTE was 18 (6, 41) days. Of these, 62% cases developed VTE after hospital discharge. In a multiple variable model including 370 cohort members, patient age at injury, male sex, increasing injury severity as reflected by the Trauma Mortality Prediction Model (TMPM) Mortality Score, immobility prior to trauma, soft tissue leg injury, and prior superficial vein thrombosis were independent predictors of VTE (C-statistic=0.78).

CONCLUSIONS

We have identified clinical characteristics which can identify patients at increased risk for VTE after acute trauma, independent of surgery. Almost two thirds of all incident VTE events occurred after initial hospital discharge (18day median time from trauma to VTE) which questions current practice of not extending VTE prophylaxis beyond hospital discharge.

Safety of the direct-acting anticoagulants in patients with atrial fibrillation: a meta-analysis

INTRODUCTION

Atrial fibrillation (AF) is known as one of the independent risk factors for stroke and might significantly increase its risk. Nowadays, direct-acting oral anticoagulants (DOACs) have been developed and demonstrated a more promising option to warfarin, the conclusion for safety is heterogeneous in different studies. It indicates the importance of comprehensive comparison of safety between DOACs and warfarin.

MATERIAL AND METHODS

Four studies including ARISTOTLE, ENGAGE AF-TIMI 48, RE-LY and ROCKET-AF were included in the meta-analysis to perform separate meta-analyses for high-dose regimen, low-dose regimen and their combination. The events included major bleeding, intracranial haemorrhage, gastrointestinal bleeding, non-major clinically relevant and minor bleeding.

RESULTS

Regardless of high dose or low dose regimen, DOACs were associated with lower risk of intracranial haemorrhage but due to no significant association for gastrointestinal bleeding, the overall effect measured by the major bleeding was also insignificant (High dose: RR=0.86, 95% CI 0.73 to 1.01; Low dose: RR=0.63, 95% CI 0.38 to 1.04). However, the combined result of high-dose and low-dose regimens showed DOACs were associated with lower risk of major bleeding events (RR=0.77, 95% CI 0.63 to 0.95).

CONCLUSIONS

Meta-analyses have showed the comparative safety of the direct-acting oral anticoagulants than warfarin in most endpoints and even better in intracranial haemorrhage. Therefore, without the need of INR monitoring, DOACs demonstrated promising alternatives to warfarin in prevention of stroke in patients with AF.