Meta-analysis of thromboembolic prophylaxis after total knee arthroplasty

Abstract

We performed a meta-analysis of the English literature to assess the efficacy of four common regimes for thromboembolic prophylaxis after total knee arthroplasty: aspirin, warfarin, low-molecular-weight heparin (LMWH) and pneumatic compression. We reviewed 136 articles and abstracts published between January 1980 and December 1997. Papers not using routine venography and a lung scan or angiography to detect deep-venous thrombosis (DVT) and pulmonary emboli (PE) respectively, were excluded. Of the 136 studies, 23 with 6001 patients were selected.The incidence of DVT was 53% (1701/3214) in the aspirin group, 45% (541/1203) in the warfarin group, 29% (311/1075) in the LMWH group, and 17% (86/509) in the pneumatic compression device group. Intermittent pneumatic compression devices and LMWH were significantly better than warfarin (p < 0.0001) or aspirin (p < 0.0001) in preventing DVT.The incidence of asymptomatic PE was 11.7% in the aspirin group (222/1901), 8.2% (101/1229) in the warfarin group and 6.3% (24/378) in the pneumatic compression group. No studies with LMWH used routine lung scans. Warfarin and pneumatic compression were significantly better than aspirin in preventing asymptomatic PE (p < 0.05).The incidence of symptomatic PE was 1.3% (23/1800) in the aspirin group, 0.4% (2/559) in the warfarin group, 0.5% (2/416) in the LMWH group and 0% (0/177) in the pneumatic compression group. No statistically significant difference was noted between the above prophylatic regimes due to the very small incidence of symptomatic PE. measurements to document a propagation rate of 24% in the calf. Therefore prophylaxis after TKA is essential to prevent thromboembolic disease. Current prophylactic methods include pharmacological regimes such as aspirin, warfarin, and low molecularweight heparin (LMWH) and mechanical techniques such as intermittent pneumatic compression devices. 1,3,5,6,11,13-18,21-25,27,29,32-38. While pharmacological prophylaxis may be useful for the prevention of thromboembolic disease, associated morbidity such as haemorrhagic complications, routine phlebotomy, excessive cost, and dosing by injection after discharge may limit its use. 1,3,6,11,13,17,18,[22][23][24]29,[32][33][34][35][37][38][39] Pneumatic compression devices offer prophylaxis without such associated morbidity, but compliance by patients and nurses is essential. In addition, the type and duration of prophylaxis after hospital discharge are controversial.To determine the relative benefit of different types of prophylaxis after TKA, we performed a meta-analysis to assess the effectiveness of four commonly used regimes of thromboembolic prophylaxis: aspirin, warfarin, LMWH and intermittent pneumatic compression devices. A metaanalysis is a technique which follows a set of statistical methods that can integrate the results of individual studies. Thus, a quantitative summary of studies with an increase in statistical power and an improvement of the estimated size of an effect can be presented.

Aspirin versus anticoagulation for prevention of venous thromboembolism major lower extremity orthopedic surgery: A systematic review and meta-analysis

“…First, we only included head-to-head randomized trials such that all included data reflect direct comparisons between aspirin and anticoagulation in well-balanced populations. Conversely, both recent reviews 11,12 were based on indirect comparisons, a type of analysis in which data for the intervention and control arms are taken from different studies and thus different populations. This methodology is not recommended by the Cochrane Collaboration 13,14 because of the increased risk of an unbalanced comparison.…”

“…4,9,10 Two previous systematic reviews comparing aspirin to anticoagulation for VTE prevention found conflicting results. 11,12 In addition, both used indirect comparisons, a method in which the intervention and comparison data come from different studies, and susceptibility to confounding is high. 13,14 We aimed to overcome the limitations of prior efforts to address this commonly encountered clinical question by conducting a systematic review and meta-analysis of randomized controlled trials that directly compared the efficacy and safety of aspirin to anticoagulants for VTE prevention in adults undergoing common highrisk major orthopedic surgeries of the lower extremities.…”

Toxic epidermal necrolysis

“…There is abundant evidence examining the efficacy for the prevention of asymptomatic deep venous thrombosis. 11 reports similar results, but notably also a dramatic risk reduction in patients treated by a post-operative compression device. Multimodal therapy and the use of intermittent mechanical compression devices have been sparsely reviewed by the literature; two recent reviews summarize the data on intermittent compression devices with results comparable or superior to chemoprophylaxis.…”

Staged venous thromboemolic events prophylaxis with low‐molecular‐weight heparin followed by aspirin is safe and effective after arthroplasty

“…35 Intermittent pneumatic calf compression is also an effective means of VTE prophylaxis. 36,37 Warwick et al reported a randomized study between foot pumps and enoxaparin that showed similar VTE prophylaxis. 38 The use of thromboprophylaxis has measurably reduced the incidence of DVT and non-fatal PE but not the rate of fatal PE or all-cause mortality.…”