Heparin-Induced Thrombocytopenia-Associated Thrombosis in Pediatric Intensive Care Patients

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Abstract
Background. Heparin-induced thrombocytopenia (HIT), a well-known side effect of heparin therapy, occurs in 1% to 5% of adults exposed to heparin. Of those, about 29% to 88% develop thrombosis. Most data on HIT-associated thrombosis in children are confined to anecdotal reports. Objective. To determine the incidence of HIT-associated thrombosis in heparin-exposed children. Methods. We performed a retrospective cohort study on all patients admitted to our pediatric intensive care unit between August 1996 and January 1999. Patients who received heparin for ≥5 days were eligible. Within these patients, we identified all cases of radiologically confirmed thrombosis. Cases of thrombosis were reviewed for fulfillment of clinical HIT criteria. HIT-associated thrombosis was confirmed serologically by determination of levels of antibodies against heparin/platelet factor 4 complexes. Results. Of 1950 children admitted during the study period, 612 were exposed to heparin for ≥5 days. Thrombosis occurred in 57 patients (9.3%). Plasma samples were available for 38 cases, of which 14 satisfied clinical HIT-criteria. Calculated incidence rate for HIT-associated thrombosis: 2.3%, (95% confidence interval: 1.3%–3.9%, for patients exposed to heparin ≥5 days). Nine patients suffered from venous, 2 patients from arterial, and 3 had combined arterial and venous thrombosis. None of the 14 patients died or underwent amputation. Six patients had heparin and platelet factor 4-complex antibody levels above the cutoff level for adults. The remaining 8 patients had significantly higher antibody levels than a matched control group. Conclusion. Compared with that reported for adults, HIT-associated thrombosis in pediatric intensive care unit patients has a similar incidence but a less severe outcome.