Background: Postthrombotic syndrome (PTS) is a common complication of deep vein thrombosis (DVT) of the lower extremities, associated with reduced quality of life and high health care costs. No reliable estimates exist of PTS risk by DVT location and its burden in the general population.

Objectives: This study estimated the risk of PTS by anatomical location of DVT and the age- and sex-specific incidence and prevalence of PTS in Europe.

Methods: We performed a systematic review and mixed-effects meta-analysis of studies reporting the cumulative incidence of PTS defined by Villalta score in patients with iliofemoral, femoropopliteal, and distal DVT. We then applied location-specific risk estimates to age- and sex-specific European DVT incidence data using a life table approach with Monte Carlo simulations to calculate the annual incidence and prevalence of PTS.

Results: Among 49 studies (N = 14 171; 15 interventional, 34 observational), estimated PTS risk was 51.1% (95% CI, 39.5%-62.7%) for iliofemoral, 30.7% (95% CI, 21.4%-39.9%) for femoropopliteal, and 22.8% (95% CI, 17.1%-29.8%) for distal DVT, assuming no systematic use of compression stockings for proximal DVT. We estimate that 250 000 (95% CI, 220 000-315 000) new PTS cases annually in Europe (incidence, 0.34 [95% CI, 0.29-0.42] per 1000) and 4.86 million (95% CI, 4.11-5.88) prevalent cases (prevalence, 6.5 [95% CI, 5.5-7.9] per 1000).

Conclusion: PTS risk increases with proximal DVT extent. Approximately 5 million individuals in Europe are estimated to live with PTS, underscoring the need for targeted prevention and treatment strategies.