Lower-limb deep-vein thrombosis in a general hospital: risk factors, outcomes and the contribution of intravenous drug use.

BACKGROUND Much of the morbidity associated with deep-vein thrombosis (DVT) is absent from the evidence base used to define best clinical practice. Intravenous (IV) drug use is an increasingly frequent cause of DVT. AIM To obtain a profile of DVT patients in routine clinical care, and determine the contribution of IV drug use. DESIGN Retrospective case-note review. METHODS We reviewed 232 episodes of lower-limb DVT in a large district general hospital during 1996. RESULTS Patients had mean (range) age 62.8 (21-97) years, with 43.9% aged > 70 years. A large proportion would have been excluded from prospective studies that have contributed to current DVT guidelines. Risk factors included smoking (33.0%), immobility (26.5%), previous DVT (23.6%), surgery in the last 3 months (18.2%), malignancy (16.5%), varicose veins (10.5%) and IV drug use (6.9%). Forty-five (19.4%) had multiple risk factors. Postsurgical DVT commonly presented from the community following initial hospital discharge. Intravenous drug use accounted for 48.4% of episodes in patients aged < or =40 years. Thrombosis was right-sided in 68.8% of IV drug users, compared to 38.2% in others (p = 0.034). DISCUSSION Our patients differed from those in most of the prospective studies used to develop routine clinical care pathways for DVT. Intravenous drug use is an important cause of community-acquired DVT in young adults.