Associations between injecting illicit drugs into the femoral vein and deep vein thrombosis: A case control study

Injecting drug use is a risk factor for deep vein thrombosis (DVT), and people who inject drugs commonly report injecting into the femoral vein. However, it is unclear whether the act of inserting a needle into the femoral vein or the pharmacodynamic properties of the injected drug increases DVT risk. We aimed to quantify the strength of association between injecting illicit drugs into the femoral vein and the odds of acquiring ileo-femoral DVT.

We used case control methodology. The study took place in Leeds, UK. A total of 313 people who inject drugs (112 'cases' with a diagnosis of DVT from hospital accident and emergency departments and 201 'controls' with no DVT from needle exchanges) completed a questionnaire about their drug use and administration routes.

The act of injecting into the femoral vein was strongly associated with DVT (χ(2) (1) = 53.453, P < 0.001), a finding that remained significant after adjusting for the type of illicit drug injected, age, gender, smoking status and history of clotting disorder. Independent of the act of femoral vein injecting, after adjusting for the effects of potential confounders, crack cocaine use was significantly associated with DVT, whereas amphetamine and heroin use were negatively independently associated with DVT.

The practice of injecting into the femoral vein in the groin and the practice of injecting crack cocaine are associated with the odds of acquiring ileo-femoral DVT. [Wright NMJ, Allgar V, Tompkins CNE. Associations between injecting illicit drugs into the femoral vein and deep vein thrombosis: A case control study. Drug Alcohol Rev 2016;35:605-610].