Duration of Treatment with Corticosteroids and Recovery of Kidney Function in Acute Interstitial Nephritis.

BACKGROUND AND OBJECTIVES: Drug-induced acute interstitial nephritis represents an emerging cause of acute kidney disease, especially among polymedicated elderly patients. Although corticosteroids are frequently used, controversy exists about the timing of initiation, efficacy, safety, and duration of treatment. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We performed a retrospective study of 182 patients with biopsy-proven drug-induced acute interstitial nephritis from 13 Spanish centers. Exposure was defined as the length of corticosteroid treatment. The main outcome was the level of serum creatinine at month 6, with respect to baseline values. RESULTS: The most common offending agents were nonsteroidal anti-inflammatory drugs (27%). In 30% of patients, the offending drug could not be identified. The median time to suspected drug withdrawal was 11 days (interquartile range, 5-22). All patients presented with acute kidney disease and were treated with corticosteroids. The mean initial dose of prednisone was 0.8±0.2 mg/kg per day. High-dose corticosteroid treatment was maintained for 2 weeks (interquartile range, 1-4). After 6 months, the mean recovered GFR was 34±26 ml/min per 1.73 m2 and ten patients required maintenance dialysis. Use of high-dose corticosteroids for 3 weeks or treatment duration >8 weeks were not associated with better recovery of kidney function. In the multivariable analysis, delayed onset of steroid treatment (odds ratio, 1.02; 95% confidence interval, 1.0 to 1.04) and the presence of interstitial fibrosis of >50% on the kidney biopsy specimen (odds ratio, 8.7; 95% confidence interval, 2.7 to 27.4) were both associated with serum creatinine level at month 6 of >75%, with respect to baseline values. CONCLUSIONS: High-dose corticosteroid treatment for 3 weeks or prolonged treatment for >8 weeks were not associated with greater kidney function recovery in drug-induced acute interstitial nephritis. A delay in the initiation of corticosteroids resulted in worse recovery of kidney function.

Cystatin C as a predictor of mortality and cardiovascular events in a population with chronic kidney disease.

Background. We examine whether cystatin C, a surrogate marker of renal function, could identify patients with chronic kidney disease (CKD) with an increased risk of renal disease progression, death, or cardiovascular events. Methods. Data were obtained for 180 patients, with a diagnosis of chronic renal failure based on serum creatinine estimated glomerular filtration rate (eGFRcreat) <90 mL/min/1.73 m(2). This population was grouped in tertiles according to cystatin C and creatinine values at baseline. Cardiovascular events and overall mortality were estimated for each tertile. Predictors of overall mortality and for the development of renal disease progression were analyzed. Results. The median age was 75 years (interquartile range 69-82) and the median eGFRcreat 38 mL/min m(2) (interquartile range 33-49). Overall mortality was lower on the first and on the second tertiles of cystatin C than on the third one (HR = 0.060; 95% CI: 0.008-0.447 and HR = 0.094; 95% CI: 0.022-0.406, resp.). Deaths related to the creatinine tertiles followed the same pattern, but differences were not as large. Cardiovascular mortality was lower on the second than on the third cystatin C tertile (HR = 0.198; 95% CI: 0.040-0.987), but it did not show differences on the first and the second creatinine tertiles compared with the third one (HR = 0.126; 95% CI: 0.013-1.265 and HR = 0.403; 95% CI: 0.093-1.740). The only independent predictors of mortality during followup were baseline cystatin C (OR = 0.100; 95% CI: 0.021-0.463) and baseline uric acid (OR = 1.377; 95% CI: 1.070-1.773). Conclusion. Cystatin C may be an alternative to creatinine for detecting a high risk of death and cardiovascular events in a population with CKD.