[Etiologies and prognostic factors of acute interstitial nephritis].

Introduction: Acute interstitial nephritis represents a clinically and etiologically heterogeneous group of kidney diseases. The aim of our study was to explore the main causes of biopsy-proven acute interstitial nephritis and to identify predictive factors of renal outcome.

Methods: We conducted a retrospective monocentric study which included patients with biopsy proven AIN, followed in our department during the period between 1980 and 2018. The non-recovery of kidney function or an estimated glomerular filtration rate˂60 mL/min/1.73 m were considered as a worse renal outcome.

Results: A total of 65 acute interstitial nephritis patients were enrolled. The mean age of patients was 41.3±16 years with a female predominance (78%). Drug-induced etiology was the most common (29%). The most frequent culprit drugs in our study were NSAID followed by antibiotics. The renal prognosis was unfavorable in 21 cases (32%). The independent predictive factors for renal outcome were : a percentage of sclerotic glomeruli greater than 15% (P=0.004), absence of interstitial edema (P˂0.001), non-use to corticosteroid therapy (P=0.02) and a delay in initiating corticosteroid therapy greater than 21 days (P=0.02).

Conclusion: Drugs currently represent the most common cause of acute interstitial nephritis. The renal prognosis is often favorable, but the progression can be towards chronic renal failure in the event of diagnostic and therapeutic delay. Our data suggest a beneficial influence of steroids on the outcome of acute interstitial nephritis.