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Low molecular weight heparin for IV drug users with DVT

Three Part Question

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

Clinical Scenario

A 26 year old IV drug user 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 to take away the need for monitoring.

Search Strategy

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

Search Outcome

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

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Lawson WL et al,
130 IVDUs over 1 year presenting with DVT 98% had at least one dose of LMWHCohort, retrospective auditIncidence of recurrent DVT and symptomatic PELow rate of symptomatic PESmall no. of patients Retrospective
McKenzie AR et al,
20 consecutive IVDUs presenting With Iliofemoral DVTCohort, retrospective case reports (4)Incidence of recurrent DVT and symptomatic PELMWH given for median of seven weeks, After three months, 8 Patients asymptomatic, 7 persistent DVT (1 declined treatment), 5 lost to Follow up. None with PE after starting treatment. 6 weeks or more treatment recommendedVery small no. of patients Retrospective


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


  1. Lawson WL, Robertson LT, Tait RC. Management of intravenous drug users with venous thromboembolism. Brit J Haematol Suppl 2003:121 Supplement 1:19.
  2. Mackenzie AR, Laing RB, Douglas JG, et al. High prevalence of iliofemoral venous thrombosis with severe groin infection among injecting drug users in north east Scotland: successful use of low molecular weight heparin with antibiotics. Postgrad Med J 2000;76(899):561-565.
  3. Lane B, Harrison M. Low molecular weight heparin or unfractionated heparin in the treatment of patients with uncomplicated deep vein thrombosis. J Accid Emerg Med 2000;17(6):402-3.