Predictors of mortality and nephrectomy in emphysematous pyelonephritis: a tertiary care centre study.

Background: Emphysematous pyelonephritis (EPN) is a deadly disease due to its associated morbidity and mortality. Attempts have been made to identify predictors of severity, mortality and need for nephrectomy in EPN with little success.

Methods: We conducted an ambispective study of EPN patients between March 2014 and September 2019. Retrospective data were collected which included age, sex, comorbidities, symptoms, signs, laboratory investigations including imaging, need for dialysis, management and any complications. All patients were then followed prospectively for renal dynamic scan, stone surgery or nephrectomy. Univariate analysis was performed to identify factors affecting mortality and need for elective nephrectomy.

Results: In total, 112 patients were included. Mean patient age was 50.01 years, 55% were female and 5% had bilateral involvement. Fever and flank pain were the most common symptoms. Diabetes was seen in 75% of cases and 30% of cases required haemodialysis at initial presentation. About 60% of patients improved with pigtail drainage. Need for nephrectomy was greater in Huang-Tseng stage 3a (14.8%). Huang-Tseng stages 3b and 4 had higher mortality rates (25%) than the other stages (2.2%). Twelve of 99 patients had non functional kidney on follow-up and underwent elective nephrectomy. Low platelet counts, high body mass index, septic shock, dialysis and higher Huang-Tseng stage were found to be predictive of mortality and renal parenchymal thickness on computed tomography scan was predictive of follow-up nephrectomy.

Conclusions: Thrombocytopaenia, high body mass index, septic shock, haemodialysis and higher Huang-Tseng stage are predictors of mortality and renal parenchymal thickness <5mm is a predictor of poor salvage of affected kidney on follow-up.