Emphysematous pyelonephritis: clinical characteristics and prognostic factors

Emphysematous pyelonephritis is a severe necrotizing infection of the renal parenchyma and perirenal tissues that is caused by gas-producing bacterial pathogens. The aim of the present study was to determine the clinical characteristics and prognostic factors of patients with emphysematous pyelonephritis.

We retrospectively analyzed the clinical and laboratory data, imaging findings, and outcomes of 32 patients with emphysematous pyelonephritis. Receiver operating characteristic curve analysis was carried out on variables that were significantly associated with patient mortality.

The overall survival rate was 87.5% (28/32). Escherichia coli (43.6%) was the most common organism cultured from urine and blood specimens. Hypoalbuminemia, shock as the presenting feature, bacteremia, need for hemodialysis and polymicrobial infection were significantly more common in cases resulting in death. The area under the receiver operating characteristic curve was 0.96. The cut-off point determined by the maximum Youden index (0.93) for three of these five factors yielded a sensitivity of 1.00 and specificity of 0.93. Shock as an initial presentation (P = 0.039) and polymicrobial infection (P = 0.010) were significantly associated with poor outcome. There were no significant differences in the clinical or laboratory features of the patients who did or did not undergo nephrectomy.

Hypoalbuminemia, shock as an initial presentation, bacteremia, indications for hemodialysis and polymicrobial infection represent prognostic factors for mortality in patients with emphysematous pyelonephritis. Patients presenting with more than two of these prognostic factors carry the highest risk of mortality, and they require timely diagnosis and aggressive management.