Shifting from inpatient to outpatient treatment of deep vein thrombosis in a tertiary care center: a cost-minimization analysis.

STUDY OBJECTIVE To compare the cost of contemporary outpatient and historical inpatient management of proximal lower limb deep vein thrombosis (DVT) in adults. DESIGN Prospective, observational study with historical inpatient cases as controls. SETTING Ambulatory thrombosis clinic of a tertiary care teaching center in Canada. PATIENTS Forty-nine inpatients with DVT from a previous study in 1996 at the same institution who would have been eligible for outpatient therapy if this option had been available, and 51 consecutive patients referred to the ambulatory thrombosis clinic for treatment of DVT between March 2000 and January 2001. INTERVENTION The 49 inpatients received unfractionated heparin, and the 51 outpatients received low-molecular-weight heparin (LMWH). MEASUREMENTS AND MAIN RESULTS A cost-minimization analysis restricted to the hospital perspective was conducted. This design was justified based on the clinical equivalence of the two treatment strategies. All direct hospital costs for treating the 51 consecutive outpatients with LMWH were measured. These data were compared with the cost of treating the inpatients with unfractionated heparin. The analysis horizon was limited to 7 days, based on the duration of hospitalization and length of heparin therapy for DVT before conversion to oral warfarin. The mean cost (in Canadian dollars) per outpatient case was 248 Canadian dollars (95% confidence interval 216-280 Canadian dollars) and was significantly different from the mean cost/inpatient case of 2826 Canadian dollars (adjusted for the difference in fiscal years) (p<0.0005). A breakdown of the outpatient cost showed that nursing time contributed to 51% of the cost, monitoring laboratory tests 5%, drugs 2%, and other costs (diagnostic laboratory tests and medical imaging) 42%. CONCLUSION Converting from inpatient to outpatient treatment of proximal DVT was associated with a significant cost savings for our institution. Accordingly, it is financially advantageous for hospitals to offer this service as it reduces direct costs and does not appear to compromise patient care.