Extended out-of-hospital low-molecular-weight heparin prophylaxis against deep venous thrombosis in patients after elective hip arthroplasty: A systematic review

Purpose: Evidence-based medicine guidelines based on venographic end points recommend in-hospital prophylaxis with low-molecular-weight heparin, (LMWH ): in patients having elective hip surgery. Emerging data suggest that out- of-hospital use may offer additional protection; however uncertainty remain s about the risk-benefit ratio. To provide clinicians with a practical! pat hway for translating clinical research, into practice, we systematically re viewed trials comparing extended out-of-hospital LMWH prophylaxis versus pl acebo. Data Sources: Studies were identified by 1) searching PubMed, MEDLINE, and the Cochrane Library Database for reports published from January 1976 to Ma y 2001, 2) reviewing references from retrieved articles; 3) scanning abstra cts from conference proceedings; and 4) contacting pharmaceutical companies and investigators of the original reports. Study Selection: Randomized, controlled trials comparing extended out-of-ho spital prophylaxis with LMWH versus placebo in patients having elective hip arthroplasty. Data Extraction. Two reviewers extracted: data independently. Reviewers eva luated! study quality by using a validated! four-item instrument. Data Synthesis: Six of seven original articles met the defined inclusion cr iteria. The included studies were double-blind trials that used proper rand omization procedures. Compared with placebo, extended out-of-hospital proph ylaxis decreased the frequency of all: episodes of deep venous thrombosis ( placebo rate, 150 of 666 patients [22.5%]; relative risk, 0.41 [95% Cl, 0.3 2 to 0.54; P < 0.001]), proximal venous thrombosis (placebo rate, 76 of 678 patients [11.2%]; relative risk, 0.31 [Cl, 0.20 to 0.47; P < 0.001]), and symptomatic venous thromboembolism (placebo rate, 36 of 862 patients [4.2%] ; relative risk, 0.36 [Cl, 0.20 to 0.67; P = 0.0011). Major bleeding was ra re, occurring in only one patient in the placebo group. Conclusions: Extended LMWH prophylaxis showed consistent effectiveness and safety in the trials (regardless of study variations in clinical practice a nd length of hospital stay) for venographic deep venous thrombosis and symp tomatic venous thromboembolism. The aggregate findings support the need for extended out-of-hospital prophylaxis in patients undergoing hip arthroplas ty surgery.