Original article
Clinical characteristics of acute kidney injury in patients with scrub typhus – RIFLE criteria validation

https://doi.org/10.1016/j.jiac.2013.08.007Get rights and content

Abstract

There are limited data available on the validity of the RIFLE classification for AKI in patients with scrub typhus. We investigated the incidence and clinical characteristics of scrub typhus associated AKI using the RIFLE criteria. From 2010 to 2012, 238 patients were diagnosed with scrub typhus. Of these, we included 223 patients who were followed up until renal recovery or for at least three months. We evaluated the incidence, clinical characteristics, and severity of AKI based on the RIFLE classification. Of the 223 patients, 47 (21%) had scrub typhus-associated AKI. The incidence of AKI was 21.1%; of which, 10.7%, 9.4% and 1% were classified as Risk, Injury and Failure, respectively. In comparison with patients in the non-AKI group, the patients in the AKI group were older (70 ± 9 vs 61 ± 14 year, P = 0.01) and had one or more comorbidities such as hypertension, diabetes, and chronic kidney disease (77% vs 22%, p = 0.01). In the AKI group, forty-four patients had AKI prior to admission, and three patients experienced AKI during their hospitalization. By multivariate logistic regression analysis, age and comorbidity were significant predictors of AKI. All patients recovered baseline renal function without renal replacement therapy following antibiotics therapy and supportive care. The incidence of AKI in patient with scrub typhus is 21%. Age and co-morbidity are significant predictors of AKI in scrub typhus. In cases of scrub typhus-associated AKI, anti-rickettsia agent and supportive care are very important.

Introduction

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi, which enters the human bloodstream through the bite of Leptotrombidium. The clinical spectrum of scrub typhus is wide, ranging from a mild infection to a severe and protracted course [1], [2], [3]. Depending on the organs involved, patients may present with pneumonitis, acute respiratory distress syndrome (ARDS), meningitis, myocarditis, acute kidney injury, or even multiple organ failure [3], [4], [5], [6].

Cases of acute kidney injury (AKI) in scrub typhus have been reported previously, with proposed mechanisms, including vasculitis, septic shock, rhabdomyolysis, direct renal invasion of O. tsutsugamushi and volume depletion [5], [6], [7], [8], [9]. However, there have been very few reports describing the incidence and clinical characteristics of acute kidney injury in patients with scrub typhus. The incidence of AKI with this infection is unclear due to the varying definitions of AKI [10], [11]. The Risk, Injury, Failure, Loss of function and End stage (RIFLE) criteria, which were originally validated for ischemic AKI [12], provide a clear definition and classification of AKI [13]. However, there are limited data available on the validity of the RIFLE classification for AKI in patients with scrub typhus.

Therefore, we investigated the incidence and clinical characteristics of scrub typhus associated AKI using the RIFLE criteria.

Section snippets

Patient selection

Between 2010 and 2012, 238 patients were diagnosed as scrub typhus, which was confirmed by a positive IgM ELISA (InBios International Inc., Seattle, WA, USA) for scrub typhus in patients with acute febrile illness and rash. Patients who were transferred to another hospital during treatment or had concomitant infections like leptospirosis, malaria, or dengue fever were excluded from the study. We also excluded patients who were not followed through complete recovery of renal function or for at

Baseline characteristics

The baseline characteristics of the 223 study subjects are presented in Table 1. The patients included 84 (38%) men and 139 (62%) women, with a mean age of 63 years (range, 18–90). Eschar was found in 204 (92%) patients in this study. Seventy-five patients had comorbidities such as hypertension, diabetes or chronic kidney disease. The mean duration of hospital stay was 6.7 days, and 209 (94%) had fever during the hospitalization period. Urinary abnormalities such as proteinuria, pyuria, or

Discussion

Scrub typhus, which is caused by Rickettsia tsutsugamushi and is transmitted by chigger bite, is an acute febrile disease that can involve many vital organs [1], [2], [3]. Scrub typhus is endemic to geographically distinct regions, which includes Japan, Taiwan, China and South Korea. The first six cases of scrub typhus were reported among United Nation's military personnel during the Korean War in 1951 [15]. However, scrub typhus had been unfamiliar to Koreans until 1986 when Korean patients

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

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