1781. Assessing the Utility of First-Contact Serum Ferritin as an Augur of Severe Thrombocytopenia in Dengue Fever

BACKGROUND: Dengue fever is an arboviral infection with global public health concerns. Much of its impact on society is attributable to the economic ramifications on public health programs, particularly in developing countries. Hospitalization accounts for 4/5th of total direct expenditure on the disease. The identification of an inexpensive biomarker to help guide the decision to hospitalize would have great utility. Serum ferritin was selected as levels reflect both infective viral load and host immune response – factors that purportedly determine the likelihood of thrombocytopenia. METHODS: The study was conducted at α = 0.05 and β = 0.05. We included patients aged ≥12 years, of both sexes, with a definite serological diagnosis of dengue fever. We excluded patients with severe anemia (hemoglobin serum ferritin levels were measured at first medical contact. Patients were monitored with serial total blood counts, until platelet counts normalized. The primary endpoint was severe thrombocytopenia, defined as platelet count nadir <20,000/µL. RESULTS: We included 64 patients in the study. The receiver-operating-characteristics (ROC) curve for the association between serum ferritin levels and the primary end-point had an area-under-curve (AUC) of 0.846, implying a good test accuracy. The ideal cut-off for “high” serum ferritin was determined to be 876 ng/mL, with levels above that predicting severe thrombocytopenia with a sensitivity of 90% and specificity of 74.07%. The negative predictive value at this threshold was 97.56%. The primary endpoint was attained by 39.13% of patients with raised ferritin vs. 2.44% with lower values (P = 0.0002). The Odd’s ratio for developing severe thrombocytopenia was 25.71. This association was consistent irrespective of sex, the day of presentation, baseline hemoglobin, or primary or secondary dengue. CONCLUSION: In appropriately selected patients, serum ferritin is a reliable indicator of severe dengue fever, helping identify patients likely to require more careful observation. [Image: see text] DISCLOSURES: All authors: No reported disclosures.