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.