Treatment of venous thromboembolism with low-molecular-weight heparin: a synthesis of the evidence published in systematic literature reviews

Tinzaparin sodium: a review of its use in the prevention and treatment of deep vein thrombosis and pulmonary embolism, and in the prevention of clotting in the extracorporeal circuit during haemodialysis

Tinzaparin sodium (Innohep) is a low molecular weight heparin (LMWH) that is effective in the prevention and treatment of deep vein thrombosis (DVT) and/or pulmonary embolism (PE), and in maintaining the patency of haemodialysis circuits in adult patients. In terms of preventing DVT and/or PE, therapy with subcutaneous tinzaparin sodium was more effective than oral warfarin and equivalent to subcutaneous enoxaparin sodium in patients undergoing orthopaedic surgery, and did not significantly differ from that of subcutaneous unfractionated heparin (UFH) in patients undergoing general surgery. In the initial therapy of adult patients with DVT and/or PE, subcutaneous tinzaparin sodium was at least as effective as intravenous UFH and did not significantly differ from subcutaneous dalteparin sodium. Various other studies have demonstrated that the long-term efficacy of subcutaneous tinzaparin sodium in the treatment of patients with DVT and/or PE was sustained for a total period of up to 12 months. Tinzaparin sodium was also demonstrated to be effective in maintaining the patency of haemodialysis circuits in adult patients with end-stage renal failure. In clinical studies, tinzaparin sodium was generally well tolerated in the prevention and treatment of DVT and/or PE in adult patients, including in elderly patients, and in patients undergoing haemodialysis. As expected, bleeding complications were the most frequently occurring adverse event. Thus, available data indicate that tinzaparin sodium is a useful option in the prevention and treatment of DVT and/or PE, and in maintaining the patency of haemodialysis circuits in adult patients.

Role of screening tests for deep venous thrombosis in asymptomatic adults with acute spinal cord injury: an evidence-based analysis

STUDY DESIGN

Systematic review.

OBJECTIVE

To examine the evidence to support practice guidelines for screening for DVT in asymptomatic adults with acute traumatic spinal cord injury (SCI) who undergo pharmacologic thromboprophylaxis.

SUMMARY OF BACKGROUND DATA

Despite the fact that pharmacologic thromboprophylaxis has been widely used since the 1980s, deep venous thrombosis (DVT) and subsequent pulmonary embolism (PE) still account for approximately 10% of deaths during the first year following SCI.

METHODS

MEDLINE and EMBASE were searched from the earliest achievable date to December 2005. We only included clinical studies that used a screening test for DVT and the gold standard diagnostic tests for DVT (i.e., lower limb venography) and for PE (i.e., lung arteriogram) in adults with traumatic SCI who underwent drug thromboprophylaxis during the acute stage after SCI.

RESULTS

The search yielded 188 articles, of which 9 articles fulfilled the criteria to be included in our review. Screening for DVT was performed in 3 randomized clinical trials and 6 case series. The protocol of these studies included the use of D-Dimer (1 of 9), I-labeled fibrinogen (2 of 9), ultrasound (1 of 9), impedance plethysmography (1 of 9), impedance plethysmography and Doppler in combination (1 of 9), Duplex (1 of 9) or venography (2 of 9) as screening test for DVT. Based on the pooled data of these studies, asymptomatic DVT was detected in 16.9% of SCI population. Only 4 studies reported the occurrence of PE in 4.4% of cases.

CONCLUSION

There is insufficient evidence to support (or refute) a recommendation for routine screening for DVT in adults with acute traumatic SCI under thromboprophylaxis. However, there is level II-2 evidence that screening could detect asymptomatic DVT in 22.7% of those individuals. Although additional investigation is needed, we hypothesize that weekly screening for DVT during the first 13 weeks post-SCI could detect most of the asymptomatic DVT events in this patient population. D-Dimer, ultrasound, and MR venography could be considered as potentially useful screening tests for DVT in the SCI population in future research studies.

Subcutaneous unfractionated heparin compared with low-molecular-weight heparin for the initial treatment of venous thromboembolism

PURPOSE OF REVIEW

Low-molecular-weight heparin is the preferred choice for the initial treatment of acute, uncomplicated venous thromboembolism. In this context, unfractionated heparin is as safe and effective as low-molecular-weight heparin but requires strict laboratory monitoring. Twice-daily subcutaneous unfractionated heparin is more effective than, and as safe as, intravenous unfractionated heparin and may simplify patient treatment in or out of the hospital, being possibly cost saving, especially if it is used in weight-based, fixed, unadjusted doses. The present review focuses on the relative values of low-molecular-weight heparin and subcutaneous unfractionated heparin for the initial treatment of venous thromboembolism.

RECENT FINDINGS

The major advantages of low-molecular-weight heparin over unfractionated heparin seem to be ease of administration and cost savings associated with home therapy or early hospital discharge; however, many patients with venous thromboembolism are still admitted to the hospital for treatment, and unfractionated heparin is extensively used to this purpose, especially in the United States. Subcutaneous unfractionated heparin, adjusted according to activated partial thromboplastin time algorithms, is as safe and effective as low-molecular-weight heparin for the treatment of venous thromboembolism, allows for quick mobilization and early discharge of suitable patients, and represents a cost-effective strategy. Fixed-dose unfractionated heparin, like low-molecular-weight heparin, may be used for the home treatment of deep vein thrombosis.

SUMMARY

Subcutaneous unfractionated heparin, targeted on activated partial thromboplastin time results or in fixed doses, may be used in or out of the hospital for the treatment of venous thromboembolism, being possibly cost effective; however, these findings need confirmation through appropriate, large-sample, randomized clinical trials.