Background: Venous thrombotic events (VTE) are a well-recognized complication in pediatric cancer patients with extremely variable incidence (1-73%). However, majority of the reports focus on symptomatic VTE. In contrast to adult literature, population-based studies on exact incidence and characteristics of asymptomatic VTE in pediatric cancer patients are lacking.

Aims: To determine the incidence and characteristics of asymptomatic VTEs in contrast to symptomatic VTEs in pediatric cancer patients.

Methods: After ethics approval, a population-based database of all pediatric oncology patients treated at the Izaak Walton Killam (IWK) Health Centre since January 2000 to December 2019, was created by amalgamating data from (i) Pediatric oncology hospital database (ii) Cancer in Young People in Canada registry (iii) pharmacy database and (iv) hospital health records. Data on patients with symptomatic and asymptomatic VTE was extracted.

All radiology reports of all patients were reviewed for VTE according to a standardized protocol. Asymptomatic VTE was defined as “Intraluminal filling defect detected within venous system (including right side of the heart and pulmonary arteries)” during imaging studies (Chest X-ray, computed tomography [CT], CT venography, magnetic resonance imaging [MRI], MR venography, ultrasound doppler [U/S], echocardiography [ECHO], venogram and linogram) in patients with no clinical history of VTEs.

Results: A total of 18390 reports were reviewed for 748 subjects. VTE incidence was: symptomatic 36 (4.81%) in 26 patients; asymptomatic/clinically unsuspected 79 (10.56%) in 56 patients. Symptomatic VTEs were significantly associated with CVL. Table 1 shows the incidence and characteristics of VTE. Most VTE were detected on ultrasonography (Table 2).

Conclusion(s): The current large population-based study establishes a best estimate of incidence and characteristics of asymptomatic VTEs in pediatric oncology patients after exhaustive review of 18390 radiological studies. With a greater understanding of asymptomatic VTE incidence, further investigation is required to explore risk factors, clinical impact and outcomes associated with asymptomatic VTE.

Table

Table 1. Incidence of VTE, location of VTE, and imaging modality used in the detection of VTE.

Table

Table 2. Frequency of all imaging modality reports reviewed and the corresponding incidence of VTE.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/epidemiology-of-asymptomatic-venous-thrombotic-events-in-pediatric-cancer-patients-a-population-based-study-from-canada/