Activated Partial Thromboplastin Time or Prothrombin Time Prolongation During Rivaroxaban Administration: Clinical Risk Factors and Outcomes Analysis

Activated partial thromboplastin time (aPTT) or prothrombin time (PT) is often detected after rivaroxaban administration, and it is known that aPTT or PT can be prolonged or normal. However, the clinical risk factors and outcomes of prolongation were unknown. In a single-center, retrospective case-control study, adult inpatients who had aPTT/PT tested before and after administration of rivaroxaban during a designated 12-month period were eligible for inclusion. Depending on whether their aPTT/PT was prolonged, patients were allocated to the prolonged case or normal control group. Demographics, rivaroxaban indications and daily dose, and laboratory values were compared. Multivariate logistic regression was used to identify independent risk factors. The changes in laboratory values and clinical outcomes were analyzed. A total of 155 patients were included in the study among which 54 (34.84%) were reported to have either or both aPTT/PT prolonged. The average prolongation time of PT was between 0.8 and 0.9 s, and 1.8 and 3.5 s for aPTT. Multivariable regression modeling showed that height (odds ratio [OR] 1.12, 95% confidence interval [CI] 1.02-1.22, P = .02) and human albumin replacement (OR 3.19, 95% CI 1.05-9.74, P = .04) were independent risk factors for aPTT/PT prolongation. The incidence of bleeding events and changes in laboratory values were similar between the groups. Patient height and receiving human albumin replacement were independent risk factors for aPTT/PT mild prolongation caused by rivaroxaban. The prolongation was not associated with an increased occurrence of bleeding events.