CLINICAL OUTCOMES IN PATIENTS WITH ACUTE PYELONEPHRITIS: A PROSPECTIVE OBSERVATIONAL STUDY

Introduction:

Published literature on the follow-up of acute pyelonephritis (APN) is limited. The primary objective of this study was to evaluate the incidence of adverse renal outcomes in patients diagnosed with APN three months after discharge from the hospital and the factors associated with these outcomes.

Methods:

This prospective observational study was conducted on patients admitted with APN at a quaternary care centre in South India from November 2023 to April 2024. The study included patients over 18 years of age admitted to the Nephrology and Urology departments, excluding pregnant patients and those with chronic kidney disease (CKD) stage 5 or on dialysis. Baseline renal function was determined using serum creatinine levels from within six months prior to admission. For patients without prior renal function tests, baseline eGFR was assumed to be 75 ml/min per 1.73 m², as per the Acute Dialysis Quality Initiative. Participants in the study were said to have adverse renal outcomes if they developed de novo CKD or progression of CKD in patients with preexisting CKD (preadmission eGFR, <60 mL/min/1.73 m2). CKD progression was defined as a ≥ 25% reduction in eGFR at 3-months post hospitalization or receiving renal replacement therapy. Electronic medical records provided demographic, clinical, radiological, and laboratory data, including urine and blood cultures, with a 3-month follow-up period after discharge.

Results:

Of the 63 patients, 19 (30.2%) had good renal outcomes (group 1) and 44 (69.8%) had poor renal outcomes (group 2). The mean ages were 63.16 ± 14.62 and 63.66 ± 8.25 years, respectively. The sex distribution was similar, with 34 (53.9%) females, and 3 patients had emphysematous pyelonephritis. Baseline CKD was present in 30 patients (47.6%), 31 (49.2%) had normal renal function, and baseline data were unavailable for 2 patients (3.2%). Fever (58%) and loin pain (80%) were the most common symptoms. Urine cultures were positive in 37 patients (58.7%), and blood cultures were positive in 10 (15.8%). E. coli was isolated in 19/47 (40.4%) cases, followed by Klebsiella pneumoniae in 7/47 (14.8%). Multidrug-resistant pathogens (resistance to one or more antimicrobials in three or more classes) were found in 17/47 (36.2%) patients, extended-spectrum β-lactamase producers in 10/47 (21.3%) patients, and carbapenem-resistant Enterobacterales in 10/47 (21.3%) patients. Imaging revealed hydroureteronephrosis in 35 patients (55.5%), with no significant outcome difference (p=0.179), and abscess formation in one patient (1.6%). Urological intervention was required in 25 patients (39.7%) (p=0.126) and hemodialysis in six patients (9.5%) (p=0.658). Acute kidney injury (AKI) occurred in 61/63 patients (96.8%). AKI (p=0.029) and pre-existing CKD (p=0.031) were significantly associated with poor renal outcomes. Among the 30 patients with CKD, 25 (83.3%) experienced CKD progression, whereas 19/33 (57.6%) developed CKD. Although baseline eGFR levels were similar, eGFR at 3 months of hospital discharge was significantly lower in group 2 (25.91 ml/min/1.73 sqm) than in group 1 (54.84 ml/min/1.73 sqm) (p<0.0001).

Conclusions:

Preexisting CKD and AKI in acute pyelonephritis are significant risk factors for adverse renal outcomes and require close follow-up.

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.