Acute kidney injury in scrub typhus

Background: We studied the urinary abnormalities and acute kidney injury (AKI) as per RIFLE criteria in scrub typhus. Methods: A prospective case record-based study of scrub typhus was carried out from January 2009 to December 2010 in a tertiary hospital in South India. Patients were followed up until renal recovery or for at least 3 months after discharge. Univariate, chi-squared tests and multivariate logistic regression analyses were performed to identify the predictors of AKI. Results: Scrub typhus was diagnosed in 259 patients. Urinary abnormalities were seen in 147 patients (56.7 %) with 60 patients (23.2 %) having AKI. All AKI patients had urinary abnormalities and 17 (28.3 %) were oliguric. Applying RIFLE (risk, injury, failure, loss, end-stage kidney disease) criteria, R, I, F were present in 23 (38.33 %), 13 (21.67 %), and 24 patients (40 %), respectively. Creatine phosphokinase (CPK) was raised in 33 patients (55 %) and hemodialysis was required in 6 patients (10 %). The case fatality rate in this study was 2 out of 259 (0.77 %), both having AKI and others recovering clinically. Significant predictors of AKI were tachycardia [odds ratio (OR) 2.28], breathlessness (OR 2.281), intensive care requirement (OR 2.43), mechanical ventilation (OR 3.33), thrombocytopenia (OR 2.90) and CPK >80 U/L (OR 1.76) by univariate analysis and intensive care requirement (adjusted OR 2.89) and thrombocytopenia (AOR 2.28) by multivariable logistic regression. Conclusion: Scrub typhus should be part of the differential diagnosis of acute febrile illness with AKI. AKI in scrub typhus is usually mild, non-oliguric, and renal recovery occurs in most patients. Rhabdomyolysis may be contributory to AKI. Thrombocytopenia and intensive care requirement are significant predictors of AKI in scrub typhus.