Clinical scenario

A 26 year old IDU with proximal DVT caused by injecting into the groin is showing poor control of their INR (and poor compliance with blood testing) while being prescribed standard warfarin. You wonder if the patient would be better managed using subcutaneous injections of low molecular weight heparin (LMWH) to take away the need for monitoring.

Three part question

In [IV drug users with DVT] are [low molecular weight heparins better than coumarins] at [safe and effective anticoagulation]?

Search strategy

Medline 1966-07/04 and Journals@OVID using the OVID interface. [exp Substance abuse, intravenous OR intravenous drug use$.mp OR exp Substance-Related disorders OR exp Injections, intravenous OR drug abuse.mp OR exp Heroin Dependence OR exp Heroin OR heroin.mp OR illicit drug$.mp OR exp street drugs OR injecting drug use$.mp OR drug depend$.mp OR drug addiction.mp] AND [exp deep vein thrombosis OR deep vein thromb$.mp OR deep venous throm$.mp OR DVT.mp] AND [exp Heparin OR Heparin.mp OR exp Heparin, Low molecular weight OR low molecular weight heparin.mp OR fractionated heparin.mp OR bemiparin.mp OR certoparin.mp OR dalteparin.mp OR enoxaparin.mp OR reviparin.mp OR tinzaparin.mp OR fragmin.mp OR clexane.mp OR exp warfarin OR warfarin.mp OR exp coumarins OR coumarins.mp] Limit to human AND English language.

Search outcome

Altogether 276 papers were identified of which 274 were irrelevant or insufficient quality for inclusion. The remaining two papers are shown in table 2.

Comment(s)

There is evidence that LMWHs are a safe and effective treatment for DVT. The drug is a recognised alternative to warfarin in certain patient groups such as pregnant women. Supervision of the INR with warfarin allows clinicians to monitor the effectiveness of the anticoagulant. With LMWHs there is no way of knowing if the patient is taking the drug, and as IDUs are traditionally seen as a chaotic patient group, then this would be a concern. There are no RCTs comparing LMWHs with coumarins in the management of intravenous drug users. Thus there is currently very limited evidence on the best ways to manage this patient group.

CLINICAL BOTTOM LINE

Low molecular weight heparin seems to be a safe method of anticoagulation and may be considered as an alternative to warfarin in the anticoagulation of IDUs because it does not require ongoing monitoring. However, the evidence is very limited. Local guidelines should be followed.