Economic Burden and Cost Determinants of Deep Venous Thrombosis During the Two Years Following Diagnosis: a Prospective Evaluation
Authors: Guanella Raphael , Ducruet Thierry , Johri Mira , Miron Marie Jose , Roussin Andre , Desmarais Sylvie , Joyal France , Kassis Jeannine , Solymoss Susan , Desjardins Louis , Ginsberg Jeffrey S. , Lamping Donna L. , Shrier Ian , Kahn Susan R. 
Published: October 2019

Abstract
Abstract 566

Background and objectives:
Deep venous thrombosis (DVT) is a common and serious vascular condition that is frequently complicated by the chronic post-thrombotic syndrome. Costs of DVT may occur over a long period and may be medical and non-medical in nature. During a Canadian multicenter cohort study of the long-term outcomes after DVT (The Venous Thrombosis Outcomes [VETO] Study), we prospectively quantified resource use and costs related to DVT during two years after DVT diagnosis, and identified clinical determinants of costs.

Methods:
The study population consisted of 355 consecutive patients diagnosed with objectively confirmed acute DVT at one of 7 participating hospitals in the province of Quebec, Canada. Using a societal perspective, we tracked total medical resource use (hospitalizations, physician visits, other health professional visits, medications, ambulance services, stockings, assistive devices) and non-medical resource use (loss of productivity, home care, transportation) incurred by DVT during the 2 years after diagnosis. Data sources included weekly patient-completed cost diaries, nurse-completed case report forms (baseline, 1, 4, 8, 12, 24 months and at any DVT-related clinical event) and the Quebec provincial administrative healthcare database (“RAMQ”). Resources for each patient were valued using individual patient level information obtained from RAMQ and patient diaries. Statistics Canada data, provincial health professionals associations and local suppliers were used to estimate resource costs if individual information was not available. The value of lost productivity was estimated using a friction-cost approach. Multivariate regression modeling for predictors of medical costs during 2 years included baseline demographic and clinical characteristics as well as the development of post-thrombotic syndrome (PTS) during study follow-up.

Results:
At study entry, mean age was 56.5 years, 50.1% were male, 2/3 were out-patients and 58.0% had proximal DVT. The mean duration of heparin and warfarin treatment was 7.6 days (SD 6.0) and 21.6 weeks (SD 10.0), respectively. During 2 years follow-up, the rate of DVT-related hospitalization was 3.5 per 100 patient-years (95% CI 2.2, 4.9). Patients reported, on average, 15.0 (SD 14.5) physician visits and 0.7 (SD 1.2) non-physician visits. Patients required 12.7 (SD 9.2) transportations, 38.6 (SD 138.0) hours of assistance and missed 12.1 (SD 39.8) workdays. The average per-patient total cost over 2 years was Can$4109 (95% CI $3658, $4561) with 63.7% of costs attributable to non-medical resource use. The two largest medical cost components were hospitalizations (Can$502; 95% CI $261, $744) and physician visits (Can$356; 95% CI $320, $392). More than two-thirds of all resource consumption occurred during the first 4 months after diagnosis. In multivariate analysis focusing on determinants of medical costs, concomitant pulmonary embolism (p = 0.002), idiopathic DVT (p= 0.003), and development of post-thrombotic syndrome during follow-up (p= 0.002) were independently associated with increased costs.

Conclusion:
The economic burden of DVT over the two years following initial diagnosis is substantial with almost two-thirds of costs attributable to non-medical resource use. Concomitant pulmonary embolism, idiopathic DVT, and development of PTS are important predictors of medical costs after DVT. Better adherence to thromboprophylaxis strategies and use of measures to prevent occurrence of PTS have the potential to diminish costs and resource utilization related to DVT.

Disclosures:
No relevant conflicts of interest to declare.