Clinical course of postthrombotic syndrome in children with history of venous thromboembolism.

Postthrombotic syndrome (PTS) is a chronic morbidity of venous thromboembolism (VTE) in children. Information about the evolution of PTS is lacking in children. Present study was aimed to evaluate the time-course of extremity PTS in children who were serially followed in a hematology clinic. This retrospective cohort study included 69 consecutive children with documented VTEs that presented with symptoms of extremity VTE: 67 extremity VTEs with or without extension to vena cava, 2 inferior vena cava VTEs. Severity of PTS was assessed using modified Villalta scale. Median age of the cohort was 12.6 years (interquartile range 1.6-15 years) while median follow-up was 28.7 months (interquartile range 13.3-33.4 months. PTS prevalence was 46.8% [95% confidence interval (CI) 37.9-57.7%]. Lower extremity VTE was associated with development of PTS compared to upper extremity VTE regardless of catheter use (P = 0.002). The time-course of PTS fluctuated in 11 of 33 children (33%; 95% CI 20-47%) at a median interval of 12 months from diagnosis of VTE (range 4-14 months): three progressed from mild/moderate to severe, one improved from moderate to mild, seven fluctuated between mild and moderate. Recurrence and incomplete resolution of VTE were associated with variability in PTS severity (P < 0.05). In summary, this study suggested that almost 50% of study cohort developed PTS, and the time-course of PTS was not static in one third of children. Future research should focus on identifying the predictors contributing to the worsening of PTS and developing risk-stratified treatment interventions so as to improve the outcome of children with VTE.