Risk factors of thromboembolic events in patients with scrub typhus

Abstract

Background Thromboembolic events are a well-recognized cause of in-hospital deaths of patients with infectious diseases. However, thromboembolic events in patients with scrub typhus, caused by Orientia tsutsugamushi have rarely been reported. This study aimed to assess risk factors associated with thromboembolic events in patients with scrub typhus. Methods All 93 scrub typhus patients’ diagnoses were confirmed serologically or by positive nested polymerase chain reaction (PCR). The clinical and laboratory findings from 12 scrub typhus patients with thromboembolic events and 81 scrub typhus patients with nonthromboembolic events were retrospectively studied. To determine the factors implicated in thromboembolic events, we performed multivariate logistic regression analysis using the six independent factors identified by the univariate analysis. Findings The mean age of the patients in the thromboembolic group was 76.4 years (median, 76 years), and in nonthromboembolic group it was 64.6 years (median, 65 years) (P<0•001). Thromboembolic events were observed in 12 patients. These events included acute coronary syndrome (n = 5), acute limb ischemia (n = 4), ischemic stroke (n = 1), deep vein thrombosis combined with pulmonary thromboembolism (n = 1), and left common iliac artery aneurysm with a thrombus (n = 1). According to multivariate analysis, the following four factors were significantly associated with the thromboembolic events: 1) treatment with rifampin (OR = 57.63; P = 0.039; CI 1.230–2700.27)., 2) Taguchi genotype (OR = 41.5; P = 0.028; CI 1.5–1154.6), 3) atrial fibrillation (OR = 9.4; P = 0.034; CI 1.2–74.0), and 4) age (OR = 1.1; P = 0.046; CI 1.0–1.3). Conclusions Our study suggests that clinicians should be cautious when managing patients with scrub typhus to avoid the development of thromboembolic events, especially in patients with risk factors such as treatment with rifampin, Taguchi genotype, atrial fibrillation, and advanced age.