Predictive factors for mortality and need for nephrectomy in patients with emphysematous pyelonephritis

OBJECTIVE To analyse the factors predicting the mortality and need for nephrectomy in patients with emphysematous pyelonephritis (EPN). PATIENTS AND METHODS Clinical features, laboratory variables, imaging studies, management strategy and the final outcomes were analysed in 39 consecutive patients with EPN. The mean (sd) age was 57 (7.2) years and the male to female ratio was 2:11. The baseline risk factors (clinical, laboratory and radiological) were compared among three groups; group 1, survived with renal salvage (26); group 2, survived after nephrectomy (eight); and group 3, died (five). RESULTS The overall survival rate was 87% (34/39) and the kidney was salvaged in 67% (26) patients at a median follow-up of 18 months. Altered mental status, thrombocytopenia, renal failure and severe hyponatremia at presentation were significantly associated with mortality rate. There was no significant difference in final outcome based on radiological classification. Extensive renal parenchymal destruction of > 50% (based on computed tomography) significantly predicted the need for nephrectomy (P < 0.001) and death (P = 0.02). Early (< 1 week) nephrectomy resulted in a higher mortality rate (three of seven patients) than initial conservative management. There were no deaths in selected patients who received antibiotics alone or had delayed nephrectomy (four patients each). Of 24 patients who had minimally invasive treatment alone, two (8%) died. Minimally invasive treatment resulted in high renal salvage (22/24, 92%). CONCLUSION Altered mental status, thrombocytopenia, renal failure and severe hyponatremia at presentation are associated with higher mortality rates, whereas extensive renal parenchymal destruction is associated with a need for nephrectomy. Early nephrectomy is associated with higher mortality rates than is initial conservative management.