Determinants of Health-Related Quality of Life after Deep Venous Thrombosis: Two-Year Results from a Canadian Multicenter Prospective Cohort Study (The VETO Study).

Background and Objectives: The long term effects of deep venous thrombosis (DVT) on health-related quality of life (QOL) have not been prospectively evaluated. During a Canadian multicentre cohort study of health and economic outcomes after DVT (the Venous Thrombosis Outcomes [VETO] Study), we measured QOL during the 2 years after DVT and evaluated the influence of development of post-thrombotic syndrome (PTS) and other determinants on QOL.

Methods: Consecutive patients diagnosed with acute DVT at seven participating hospital centres were recruited from April 2001-July 2002. During study visits at Baseline, 1, 4, 8, 12 and 24 months, clinical data were collected, a standardized assessment for PTS was performed and QOL questionnaires were self-completed. Generic QOL was measured using the SF-36 Health Survey questionnaire. Venous disease-specific QOL was measured using the VEINES-QOL questionnaire. For both questionnaires, lower scores indicate poorer QOL. Mean QOL at each time point and change in QOL scores over 24 months follow-up were quantified. The influence of PTS and other clinical or demographic characteristics on QOL was evaluated using multivariate regression analyses.

Results: Of the 359 patients recruited, 49% were male, average age was 56 years, 2/3 were outpatients and 55% had proximal DVT. The cumulative incidence of PTS during follow-up was 37%. On average, QOL scores in the cohort improved during follow-up (mean improvement from Baseline to 24 months: 7.2 points for SF-36 mental component summary (MCS), 7.5 points for SF-36 physical component summary (PCS) and 4.7 points for VEINES-QOL). Patients who developed PTS, compared with those who did not, had significantly lower PCS scores and VEINES-QOL scores at all 5 follow-up visits (differences for PTS vs. no PTS ranged from 2.4-9.0 points for PCS and from 4.5-6.0 points for VEINES-QOL), and significantly lower MCS scores at the 1, 4, 8 and 12 month visits (differences ranged from 3.7–4.7 points). Multivariate regression analyses adjusted for age, sex and comorbidity showed that PTS and proximal (vs. distal) location of initial DVT were strong independent predictors of lack of improvement of PCS scores (p=.003 and .02, respectively) and VEINES-QOL scores (p=.006 and .009, respectively) during follow-up, but not of MCS scores (p=0.054 and 0.86, respectively). Variables such as body mass index, concurrent pulmonary embolism at time of DVT diagnosis and previous history of DVT did not influence change in scores for any QOL measure.

Conclusions: The principal determinants of quality of life after DVT are development of PTS and proximal (vs. distal) location of initial DVT. Our study provides valuable prognostic information on health outcomes after DVT.