Clinical significance of abnormal chest radiographic findings for acute kidney injury in patients with scrub typhus

Background: Abnormal chest radiographs are frequently encountered in patients with scrub typhus. This study aimed to investigate whether chest radiography on admission is significant as a predictive factor for acute kidney injury (AKI) in patients with scrub typhus. Methods: From 2010 to 2016, 467 patients were diagnosed with scrub typhus in our hospital. We divided the patients into two groups: normal chest radiograph (NCR) and abnormal chest radiograph (AbNCR), based on chest radiography findings. The incidence, clinical characteristics, and severity of AKI were compared between AKI and non-AKI groups according to the RIFLE classification. Results: Of the 467 patients, 96 (20.6%) constituted the AbNCR group. Compared with NCR patients, AbNCR patients were older (71 +/- 11 vs. 62 +/- 13 years, P < 0.001) and had higher total leukocyte counts (9.43 x 10(3)/mL vs. 6.98 x 10(3)/mL, P < 0.001). The AbNCR group had significantly longer duration of hospital stay (8.9 +/- 5.5 vs. 6.3 +/- 2.8 days, P < 0.001) and higher incidence of AKI (46.9% vs. 15.1%, P < 0.001). The common abnormal chest radiographic findings were pulmonary abnormalities, such as pulmonary congestion and pleural effusion. The overall AKI incidence was 21.6%, of which 12.4%, 7.9%, and 1.3% cases were classified as risk, injury, and failure, respectively. In a multivariable logistic regression analysis for association with AKI, old age, presence of chronic kidney disease or hypertension, leukocytosis, hypoalbuminemia, and chest radiographic abnormalities on admission were significant predictors of AKI. Conclusion: Chest radiographic abnormalities on admission were independently associated with AKI in patients with scrub typhus.