Activated Partial Thromboplastin Time (aPTT) as a Screening Test for Predicting Bleeding Manifestations in Adult Patients with Dengue Infection – A Diagnostic Accuracy Study

Abstract Background: Thrombocytopenia has been well established in dengue infections; however, coagulopathy is yet to be explored. Objective: The primary outcome was to assess derangement of activated partial thromboplastin time (aPTT) as a predictor of bleeding manifestations and severity of disease in dengue. Methods: This prospective cohort study included adults with dengue fever confirmed by serology, presenting to a single tertiary care center in South India. A structured questionnaire was used to extract clinical features and laboratory parameters at presentation, including aPTT. The patients were clinically observed during their course of illness for the outcomes of major and minor bleeding manifestations along with features of severe dengue. Results: Between May 2020 and September 2021, 140 patients were screened and 122 were recruited. Among these, 72 patients had normal aPTT and 50 had deranged aPTT. There were 41 bleeding events noted and 35 patients had severe dengue. There was a statistically significant correlation for aPTT derangement with major bleeding events (relative risk [RR] =4.03 [95% confidence interval (CI): 1.6–10.5]; P = 0.002), with minor bleeding events (RR = 2.52 [95% CI: 1.1–5.6]; P = 0.017) and with severity of dengue (RR = 3.14 [95% CI: 1.7–5.8); P < 0.001]. aPTT had a good negative predictive value of 93.1% (95% CI: 84.5–97.7) for major bleeding. There was no statistically significant correlation between thrombocytopenia and bleeding manifestations. Conclusion: aPTT can be used as an indicator for predicting bleeding events and severity in dengue fever, with a good negative predictive value.