Heparin for venous thromboembolism prophylaxis in patients with acute spinal cord injury: a systematic review and meta-analysis

Objective: The objective of this study is to systematically review and estimate the effect of heparin for thromboprophylaxis in patients with acute spinal cord injury (SCI). Methods: We searched the PubMed database up to February 2013. Only randomized control trials (RCTs), quasi-RCTs, cohorts, case-control and cross-sectional studies were included. The incidence of venous thromboembolism (VTE) and major bleeding complication were recorded as the endpoints. The summary relative risks (RR) were calculated by meta-analysis. Results: A total of 18 studies with 2578 patients were included. Four studies evaluated the effects of low-dose unfractionated heparin (LDUH) compared placebo or untreated. No significant differences were observed, with the summary RR 0.661 (95% confidence interval (CI) 0.365-1.199; Z = 1.36, P = 0.173) for VTE. Only one RCT compared fixed-dose LDUH with adjusted-dose LDUH, which showed lower VTE incidence but higher bleeding incidence for adjusted dose. Nine trials have compared LDUH with low-molecular-weight heparin (LMWH). No significant differences were observed for VTE with the summary RR 1.633 (95% CI 0.822-3.243; Z = 1.40, P = 0.162). But major bleeding was lower with LMWH (summary RR 2.034, 95% CI 1.018-4.063; Z = 2.01, P = 0.044). Three studies compared different LMWHs, which included one for enoxaparin versus tinzaparin and two for enoxaparin versus dalteparin. No significant differences were observed with the summary RR 0.694 (95% CI 0.336-1.434; Z = 0.99, P = 0.324) for VTE. Three studies compared different dose of LMWH. No differences were observed. Conclusion: Our meta-analysis showed that in patients with acute SCI, LDUH have no thromboprophylaxis effect compared with placebo or untreated; LMWH seems only can reduce bleeding incidence, but not prophylaxis thromboembolism compared with LDUH. Because of no good quality studies existed in this setting, well-designed RCTs are urgently needed.