Outcomes vary in children with lower extremity DVT based on triggering event, sex

The development of post-thrombotic syndrome in children with lower extremity deep vein thrombosis appeared related to DVT triggering event, sex and residual thrombosis, according to retrospective study results published in Blood.

Overall, children with line-related lower extremity DVT tended to have more benign outcomes than children with non–line-related DVT, results showed.

“Venous thrombotic events are increasingly being diagnosed in the pediatric population,” Maria Laura Avila, MD, of The Hospital for Sick Children in Toronto, and colleagues wrote. “As a consequence of the increased number of VTE cases, the number of VTE–related complications are also expected to rise and become a relevant health care problem in pediatric care.”

Possible complications include recurrent thrombosis, pulmonary embolism, post-thrombotic syndrome and death. Post-thrombotic syndrome — defined as chronic venous symptoms or signs secondary to DVT — has been reported frequently in adult patients with lower extremity DVT and children with thrombotic events in the upper or lower venous territory.

Avila and colleagues evaluated data from 339 children with diagnosed lower extremity DVT.

The researchers considered characteristics of the index line-related DVT based on triggering event — line-related vs. non–line-related DVT — to divide patients into three groups: non–line-related DVT (n = 56), line-related DVT in neonates (n = 95), and line-related DVT in non-neonates (n = 188).

The incidence of lower extremity post-thrombotic syndrome served as the study’s primary endpoint. Secondary outcome measures included resolution of DVT, DVT recurrence, PE and death.

Overall, post-thrombotic syndrome occurred more frequently in children with non–line-related DVT (62.5%) than in neonates with line-related DVT (40%) and non-neonates with line-related DVT (46.3%; P = .04).

Children with non–line-related DVT also more commonly experienced recurrent lower extremity DVT (10.7% vs. 2%; P = .001) and PE (19.6% vs. 3.2%; P < .001) that non-neonates with line-related DVT.

The researchers did not observe a significant difference in lower extremity DVT resolution between groups. Further, although six patients died during follow-up, no deaths were caused by thrombotic events.

A multivariate analysis found that sex, triggering event and degree of DVT resolution were predictive of post-thrombotic syndrome, based on a Modified Villalta Score greater than one. Further, the association based on sex varied by triggering event.

The researchers found that post-thrombotic syndrome–free survival significantly differed across groups (log-rank test P < .001). Median time to a Modified Villalta Score greater than one was 2 years (95% CI, 1.1-3.2) for children in the non–line-related DVT, 5.1 years (95% CI, 4.1-6.5) for non-neonates with line-related DVT and 10.5 years (95% CI, 7-not estimable) for neonates with line-related DVT.

Children with non–line-related DVT had a Modified Villalta Score of 1.33 at the time of the first post-thrombotic syndrome assessment. In comparison, children with line-related DVT had significantly lower Modified Villalta Scale scores at baseline (neonates, 1.01 lower; non-neonates, 0.65 lower, P< .001 for both). The score increased by 0.05 each year across groups; however, researchers did not observe a difference on score variation across groups over time.

The researchers acknowledged study limitations, including the retrospective design and the inability to consider treatment platforms.

“There are several knowledge gaps in lower extremity DVT and pediatric post-thrombotic syndrome that remain to be solved,” Avila and colleagues wrote. “For example, the factors that lead to better outcomes in thrombolysis remain to be identified. Also, the scoring systems of pediatric tools need to be improved, to allow monitoring changes in individual clinical features of post-thrombotic syndrome over time.” – by Cameron Kelsall

Disclosure: The researchers report no relevant financial disclosures.