Developing and validating an algorithm to identify incident chronic dialysis patients using administrative data.

BACKGROUND: Administrative healthcare databases are widespread and are often standardized with regard to their content and data coding, thus they can be used also as data sources for surveillance and epidemiological research. Chronic dialysis requires patients to frequently access hospital and clinic services, causing a heavy burden to healthcare providers. This also means that these patients are routinely tracked on administrative databases, yet very few case definitions for their identification are currently available. The aim of this study was to develop two algorithms derived from administrative data for identifying incident chronic dialysis patients and test their validity compared to the reference standard of the regional dialysis registry. METHODS: The algorithms are based on data retrieved from hospital discharge records (HDR) and ambulatory specialty visits (ASV) to identify incident chronic dialysis patients in an Italian region. Subjects are included if they have at least one event in the HDR or ASV databases based on the ICD9-CM dialysis-related diagnosis or procedure codes in the study period. Exclusion criteria comprise non-residents, prevalent cases, or patients undergoing temporary dialysis, and are evaluated only on ASV data by the first algorithm, on both ASV and HDR data by the second algorithm. We validated the algorithms against the Emilia-Romagna regional dialysis registry by searching for incident patients in 2014 and performed sensitivity analyses by modifying the criteria to define temporary dialysis. RESULTS: Algorithm 1 identified 680 patients and algorithm 2 identified 676 initiating dialysis in 2014, compared to 625 patients included in the regional dialysis registry. Sensitivity for the two algorithms was respectively 90.8 and 88.4%, positive predictive value 84.0 and 82.0%, and percentage agreement was 77.4 and 74.1%. CONCLUSIONS: Algorithms relying on retrieval of administrative records have high sensitivity and positive predictive value for the identification of incident chronic dialysis patients. Algorithm 1, which showed the higher accuracy and has a simpler case definition, can be used in place of regional dialysis registries when they are not present or sufficiently developed in a region, or to improve the accuracy and timeliness of existing registries.

Temporal validation of the CT-PIRP prognostic model for mortality and renal replacement therapy initiation in chronic kidney disease patients.

BACKGROUND: A classification tree model (CT-PIRP) was developed in 2013 to predict the annual renal function decline of patients with chronic kidney disease (CKD) participating in the PIRP (Progetto Insufficienza Renale Progressiva) project, which involves thirteen Nephrology Hospital Units in Emilia-Romagna (Italy). This model identified seven subgroups with specific combinations of baseline characteristics that were associated with a differential estimated glomerular filtration rate (eGFR) annual decline, but the model's ability to predict mortality and renal replacement therapy (RRT) has not been established yet. METHODS: Survival analysis was used to determine whether CT-PIRP subgroups identified in the derivation cohort (n = 2265) had different mortality and RRT risks. Temporal validation was performed in a matched cohort (n = 2051) of subsequently enrolled PIRP patients, in which discrimination and calibration were assessed using Kaplan-Meier survival curves, Cox regression and Fine & Gray competing risk modeling. RESULTS: In both cohorts mortality risk was higher for subgroups 3 (proteinuric, low eGFR, high serum phosphate) and lower for subgroups 1 (proteinuric, high eGFR), 4 (non-proteinuric, younger, non-diabetic) and 5 (non-proteinuric, younger, diabetic). Risk of RRT was higher for subgroups 3 and 2 (proteinuric, low eGFR, low serum phosphate), while subgroups 1, 6 (non-proteinuric, old females) and 7 (non-proteinuric, old males) showed lower risk. Calibration was excellent for mortality in all subgroups while for RRT it was overall good except in subgroups 4 and 5. CONCLUSIONS: The CT-PIRP model is a temporally validated prediction tool for mortality and RRT, based on variables routinely collected, that could assist decision-making regarding the treatment of incident CKD patients. External validation in other CKD populations is needed to determine its generalizability.

Low-protein diets for chronic kidney disease patients: the Italian experience.

BACKGROUND: Nutritional treatment has always represented a major feature of CKD management. Over the decades, the use of nutritional treatment in CKD patients has been marked by several goals. The first of these include the attainment of metabolic and fluid control together with the prevention and correction of signs, symptoms and complications of advanced CKD. The aim of this first stage is the prevention of malnutrition and a delay in the commencement of dialysis. Subsequently, nutritional manipulations have also been applied in association with other therapeutic interventions in an attempt to control several cardiovascular risk factors associated with CKD and to improve the patient's overall outcome. Over time and in reference to multiple aims, the modalities of nutritional treatment have been focused not only on protein intake but also on other nutrients. DISCUSSION: This paper describes the pathophysiological basis and rationale of nutritional treatment in CKD and also provides a report on extensive experience in the field of renal diets in Italy, with special attention given to approaches in clinical practice and management. Italian nephrologists have a longstanding tradition in implementing low protein diets in the treatment of CKD patients, with the principle objective of alleviating uremic symptoms, improving nutritional status and also a possibility of slowing down the progression of CKD or delaying the start of dialysis. A renewed interest in this field is based on the aim of implementing a wider nutritional therapy other than only reducing the protein intake, paying careful attention to factors such as energy intake, the quality of proteins and phosphate and sodium intakes, making today's low-protein diet program much more ambitious than previous. The motivation was the reduction in progression of renal insufficiency through reduction of proteinuria, a better control of blood pressure values and also through correction of metabolic acidosis. One major goal of the flexible and innovative Italian approach to the low-protein diet in CKD patients is the improvement of patient adherence, a crucial factor in the successful implementation of a low-protein diet program.

A clinical stratification tool for chronic kidney disease progression rate based on classification tree analysis.

BACKGROUND: Registry-based studies have identified risk factors for chronic kidney disease (CKD) and for progression to end-stage renal disease. However, usually, these studies do not incorporate sequential measurements of kidney function and provide little information on the prognosis of individual patients. The aim of this study is to identify which combinations of demographic and clinical characteristics are useful to discriminate patients with a differential annual decline in glomerular filtration rate (GFR). METHODS: This observational retrospective study includes patients enlisted in the registry of the Prevention of Progressive Renal Insufficiency Project of Emilia-Romagna region (Italy) from July 2004 to June 2010, with at least four serum creatinine measurements. Classification tree analysis (CTA) was used to identify subgroups of patients with a different annual GFR decline using demographic and laboratory data collected at study entry. RESULTS: The CTA procedure generated seven mutually exclusive groups. Among patients with proteinuria, those with a baseline estimated GFR (eGFR) of >33 mL/min/1.73 m(2) exhibited the fastest illness progression in the study population (-3.655 mL/min/1.73 m(2)), followed by patients with a baseline eGFR of <33 mL/min/1.73 m(2) and a baseline serum phosphorus of >4.3 mg/dL (-2.833 mL/min/1.73 m(2)). Among patients without proteinuria, those aged <67 years exhibited a significantly faster progression, which was even faster for the subgroup with diabetes. Among patients aged >67 years, females had on average a stable eGFR over time, with a large variability. CONCLUSIONS: It is possible to rely on a few variables typically accessible in routine clinical practice to stratify patients with a different CKD progression rate. Stratification can be used to guide decisions about the follow-up schedule, treatments to slow progression of kidney disease, prevent its complications and to begin planning for dialysis and transplantation.

Chronic renal disease and risk of cardiovascular morbidity-mortality.

The pathogenesis of cardiovascular disease in CKD differs subtly from that of non-CKD patients. As renal function declines, the role and impact of treating classical risk factors may change and diminish. However, hypertension, hypercholesterolaemia and smoking cessation management should be optimized and may require multiple agents and approaches, particularly as CKD advances. Hypertension treatment would appear to be one management area in which performance is less than ideal. Moreover there are mechanisms and risk factors that are specific to CKD, capable of triggering a vascular pathology and that justify the surplus of CV morbidity in CKD patients and that require we consider CKD as a CV risk factor per se. In the initial stages of CKD it would be advisable to implement all the preventative measures to stem the onset of CV disease, whereas in the more advanced stages a multifactorial approach is likely to be necessary, as we have learned from the STENO-study within the diabetes.

Primary membranous nephropathy in the Italian region of Emilia Romagna: results of a multicenter study with extended follow-up.

BACKGROUND: Since primary membranous nephropathy is a heterogeneous disease with variable outcomes and multiple possible therapeutic approaches, all 13 Nephrology Units of the Italian region Emilia Romagna decided to analyze their experience in the management of this challenging glomerular disease. METHODS: We retrospectively studied 205 consecutive adult patients affected by biopsy-proven primary membranous nephropathy, recruited from January 2010 through December 2017. The primary outcome was patient and renal survival. The secondary outcome was the rate of complete remission and partial remission of proteinuria. Relapse incidence, treatment patterns and adverse events were also assessed. RESULTS: Median (IQR) follow-up was 36 (24-60) months. Overall patient and renal survival were 87.4% after 5 years. At the end of follow-up, 83 patients (40%) had complete remission and 72 patients (35%) had partial remission. Among responders, less than a quarter (23%) relapsed. Most patients (83%) underwent immunosuppressive therapy within 6 months of biopsy. A cyclic regimen of corticosteroid and cytotoxic agents was the most commonly used treatment schedule (63%), followed by rituximab (28%). Multivariable analysis showed that the cyclic regimen significantly correlates with complete remission (odds ratio 0.26; 95% CI 0.08-0.79) when compared to rituximab (p < 0.05). CONCLUSIONS: In our large study, both short- and long-term outcomes were positive and consistent with those published in the literature. Our data suggest that the use of immunosuppressive therapy within the first 6 months after biopsy appears to be a winning strategy, and that the cyclic regimen also warrants a prominent role in primary membranous nephropathy treatment, since definitive proof of rituximab superiority is lacking.

The PIRP project (Prevenzione Insufficienza Renale Progressiva): how to integrate hospital and community maintenance treatment for chronic kidney disease.

Chronic kidney disease (CKD) represents a global health burden with great economic impact on healthcare and therefore it requires appropriate interventions by Health Care Systems. The PIRP (Prevenzione Insufficienza Renale Progressiva) project is endorsed and funded by the Emilia-Romagna Regional Health Board and involves all the Nephrology Units of the Emilia-Romagna Region (Italy). The project has a predominantly clinical purpose and is expected to bring about a continuous quality improvement in the treatment of patients with CKD. Its aims are to intercept patients in an early phase of CKD, to delay their illness progression and to prevent cardiovascular complications. An integrated care pathway involving nephrologists, general practitioners (GPs) and other specialists has been created to identify patients to whom ambulatory care targeted on effective, efficient pharmaceutical and dietary treatment as well as on lifestyle modifications is subsequently provided. With the cooperation of GPs, in its 13 years of activity the project identified and followed up more than 25,000 CKD patients, who attended the Nephrology units with more than 100,000 visits. The effects of a closer and joint monitoring of CKD patients by GPs and nephrologists can be quantified by the reduction of the mean annual GFR decline (average annual CKD-EPI change: - 0.34 ml/min), and by the decrease in the overall incidence of patients who annually started dialysis in the Emilia-Romagna Region, that dropped from 218.6 (× million) in 2006 to 197.5 (× million) in 2016, corresponding to about 100 cases.

[The accuracy of hospital discharge records and their use in identifying and staging chronic kidney disease].

Administrative databases contain precious information that can support the identification of specific pathologies. Specifically, chronic kidney disease (CKD) patients could be identified using hospital discharge records (HDR); these should contain information on the CKD stage using subcategories of the ICD9-CM classification's 585 code (subcategories can be expressed just by adding a fourth digit to this code). To verify the accuracy of HDR data regarding the coding of CKD collected in the Italian region Emilia-Romagna, we analyzed the HDR records of patients enrolled in the PIRP project, which could easily be matched with eGFR data obtained through laboratory examinations. The PIRP database was used as the gold standard because it contains data on CKD patients followed up since 2004 in thirteen regional nephrology units and includes data obtained from reliable and homogeneous laboratory measurement. All HDR of PIRP patients enrolled between 2009 and 2017 were retrieved and matched with available laboratory data on eGFR, collected within 15 days before or after discharge. We analyzed 4.168 HDR, which were classified as: a) unreported CKD (n=1.848, 44.3%); b) unspecified CKD, when code 585.9 (CKD, not specified) or 586 was used (n=446, 10.7%); c) wrong CKD (n=833, 20.0%); d) correct CKD (n=1041, 25.0%). We noticed the proportion of unreported CKD growing from 32.9% in 2009 to 56.6% in 2017, and the correspondent proportion of correct CKDs decreasing from 25.4% to 22.3%. Across disciplines, Nephrology showed the highest concordance (69.1%) between the CKD stage specified in the HDRs and the stage reported in the matched laboratory exam, while none of the other disciplines, except for Geriatrics, reached 20% concordance. When the CKD stage was incorrectly coded, it was generally underestimated; among HDRs with unreported or unspecified CKD at least half of the discharges were matched with lab exams reporting CKD in stage 4 or 5. We found that the quality of CKD stage coding in the HDR record database was very poor, and insufficient to identify CKD patients unknown to nephrologists. Moreover, the growing proportion of unreported CKD could have an adverse effect on patients' timely referral to a nephrologist, since general practitioners might remain unaware of their patients' illness. Actions aimed at improving the training of the operators in charge of HDRs compilation and, most of all, at allowing the exploitation of the informative potential of HDRs for epidemiological research are thus needed.

[Hyperkalemia as a limiting factor in the use of drugs that block the Renin Angiotensin Aldosterone System (RAAS)].

Angiotensin-converting enzyme (ACE-I) inhibitors and ARBs have shown real efficacy in reducing blood pressure, proteinuria, in slowing the progression of chronic kidney disease (MRC) and in clinical improvement. in patients with heart failure, diabetes mellitus and ischemic heart disease. However, their use is limited by some side effects such as the increase in serum potassium (K), which can be particularly severe in patients with renal insufficiency. In the 23,000 patients followed by the PIRP project of the Emilia-Romagna Region, hyperkalaemia at the first visit (K> 5.5 mEq / L) was present in about 7% of all patients. The prevalence of K values> 5.5 mEq / L increased in relation to the CKD stage, reaching 11% in patients in stage 4 and 5. Among patients with values of K> 5.5 at baseline, 44.8% were in therapy with ACE-I / ARB inhibitors, 3.8% with anti-mineralcortoid and a further 3.9% concurrently taking SRAA-blocking agents and K-sparing diuretics. Counter-measures to avoid the onset of hyperkalemia during treatment with drugs that block the RAAS range from the low-K diet, to diuretics and finally to drugs that promote fecal elimination of K. Among these, polystyrene sulfonates, which have more than 50 years of life, exchange K with sodium or calcium. These drugs, however, in chronic use, can lead to sodium or calcium overload and cause dangerous intestinal necrosis. Recently two new highly promising drugs have been introduced on the market for the treatment of hyperkalemia, the patiromer and sodium zirconium cyclosilicate. The patiromer, which is a potassium-calcium exchanger, acts at the level of the colon where there is a higher concentration of K and where the drug is most ionized. Sodium zirconium cyclosilicate (ZS-9) is a resin with micropores of well-defined dimensions, placed in the crystalline structure of the zirconium silicate. The trapped K is exchanged with other protons and sodium. However, even these drugs will have to demonstrate their long-term efficacy and safety to be considered true partners of RAAS blockers in some categories of patients.

[Challenges and results of the PIRP project (Prevenzione della Insufficienza Renale Progressiva) of the Emilia-Romagna Region].

The PIRP project was conceived in 2004; with the aim to face the increased prevalence of chronic kidney disease (CKD) associated with the aging and increased survival of the population. The first phase of the project consisted of training primary care physicians to identify people at risk of CKD and to implement intervention strategies that proved to be effective in preventing CKD it or delaying its progression once it is established. In the second phase of the project, dedicated ambulatories were opened in the nephrology units of Emilia-Romagna hospitals to provide an in-depth assessment and personalized care to CKD patients, following them up until renal failure or death or referring them back to general practitioners, according to the study protocol. A web-based registry was implemented to collect demographic and clinical data on PIRP patients. As of 30 June 2018, the registry included 26.211 CKD patients, with a median follow-up of 24.5 months. Over the 14 years of the PIRP the mean age of incident patients increased from 71.0 years to 74.2 years and the mean eGFR increased from 30.56 to 36.52 mL/min/1.73 m ², proving that the project was successful in recruiting older patients with a better renal function. At 5 years, the percentage of patients still active in the project was =45%.The implementation of the project has seen a reduction in the number of patients arriving every year to the dialysis treatment in E-R (about 100 units less from 2006 to 2016). The PIRP cohort is the largest in Italy and in Europe, which makes it ideal for research based on international comparisons and as a model for national registries.

Interaction of healthcare staff's attitude with barriers to physical activity in hemodialysis patients: A quantitative assessment.

BACKGROUND AND AIM OF THE STUDY: In hemodialysis patients, sedentarism is a potentially modifiable mortality risk factor. We explored whether healthcare staff's attitude towards exercise interacts with patient-perceived barriers in modifying the level of physical activity in this population. METHODS: In this prospective, cross-sectional, multicenter study we recruited 608 adult patients and 330 members of the healthcare staff in 16 hemodialysis units in Italy. We assessed patient-perceived barriers to, and healthcare staff's attitude towards, exercise by specific questionnaires. We fitted multilevel linear models to analyze the relationships of either barriers or staff's attitude, and their interaction, with a measure of patient self-reported physical activity (the Human Activity Profile-Adjusted Activity Score [HAP-AAS]), adjusting for multiple confounders. We also employed latent class analysis to dichotomize patients into those endorsing or not endorsing barriers. RESULTS: Most barriers were negatively associated with the HAP-AAS (adjusted change attributable to a given barrier ranging between -5.1 ["Feeling too old", 95% Confidence Interval: -9.4 to -0.8] and -15.6 ["Ulcers on legs and feet", 95%CI: -24.8 to -6.5]. We found a significant interaction between staff's attitude and barriers (adjusted P values ranging between 0.03 ["I do not believe that it is physician's or nurse's role providing advice on exercise to patients on dialysis"] and 0.001 ["I do not often ask patients about exercise"]). A beneficial effect of a proactive staff's attitude was evident only in patients not endorsing barriers. CONCLUSIONS: Barriers and non-proactive staff's attitude reduce physical activity in hemodialysis patients. Patients not endorsing barriers benefit the most from a proactive staff's attitude.

Correction: Interaction of healthcare staff's attitude with barriers to physical activity in hemodialysis patients: A quantitative assessment.

[This corrects the article DOI: 10.1371/journal.pone.0196313.].

Nutritional treatment of advanced CKD: twenty consensus statements.

The Italian nephrology has a long tradition and experience in the field of dietetic-nutritional therapy (DNT), which is an important component in the conservative management of the patient suffering from a chronic kidney disease, which precedes and integrates the pharmacological therapies. The objectives of DNT include the maintenance of an optimal nutritional status, the prevention and/or correction of signs, symptoms and complications of chronic renal failure and, possibly, the delay in starting of dialysis. The DNT includes modulation of protein intake, adequacy of caloric intake, control of sodium and potassium intake, and reduction of phosphorus intake. For all dietary-nutritional therapies, and in particular those aimed at the patient with chronic renal failure, the problem of patient adherence to the dietetic-nutritional scheme is a key element for the success and safety of the DNT and it can be favored by an interdisciplinary and multi-professional approach of information, education, dietary prescription and follow-up. This consensus document, which defines twenty essential points of the nutritional approach to patients with advanced chronic renal failure, has been written, discussed and shared by the Italian nephrologists together with representatives of dietitians (ANDID) and patients (ANED).

[Nutritional diet therapy in the management of the patient with Chronic Kidney Disease in advanced phase to delay the beginning and reduce the frequency of dialysis. An option also in the pre-emptive transplant program].

The Italian nephrology has a long tradition and experience in the field of dietetic-nutritional therapy (DNT), which is an important component in the conservative management of the patient suffering from a chronic kidney disease, which precedes and integrates the pharmacological therapies. The objectives of DNT include the maintenance of an optimal nutritional status, the prevention and / or correction of signs, symptoms and complications of chronic renal failure and, possibly, the delay in starting of dialysis. The DNT includes modulation of protein intake, adequacy of caloric intake, control of sodium and potassium intake, and reduction of phosphorus intake. For all dietary-nutritional therapies, and in particular those aimed at the patient with chronic renal failure, the problem of patient adherence to the dietetic-nutritional scheme is a key element for the success and safety of the DNT and it can be favored by an interdisciplinary and multi-professional approach of information, education, dietary prescription and follow-up. This consensus document, which defines twenty (20) essential points of the nutritional approach to patients with advanced chronic renal failure, has been written, discussed and shared by the Italian nephrologists together with representatives of dietitians (ANDID) and patients (ANED).

Controversial issues in CKD clinical practice: position statement of the CKD-treatment working group of the Italian Society of Nephrology.

This position paper of the study group "Conservative treatment of Chronic Kidney Disease-CKD" of the Italian Society of Nephrology addresses major practical, unresolved, issues related to the conservative treatment of chronic renal disease. Specifically, controversial topics from everyday clinical nephrology practice which cannot find a clear, definitive answer in the current literature or in nephrology guidelines are discussed. The paper reports the point of view of the study group. Concise and practical advice is given on several common issues: renal biopsy in diabetes; dual blockade of the renin-angiotensin-aldosterone system (RAAS); management of iron deficiency; low protein diet; dietary salt intake; bicarbonate supplementation; treatment of obesity; the choice of conservative therapy vs. dialysis. For each topic synthetic statements, guideline-style, are reported.

Excess mortality attributable to chronic kidney disease. Results from the PIRP project.

Although chronic kidney disease (CKD) has a high mortality rate, the estimation of CKD mortality burden in the general population may be challenging because CKD is not always listed as a cause of death in mortality registries. To overcome this limitation, relative survival was used to estimate the excess mortality attributable to CKD as compared to the general population using data of patients registered in the Prevenzione Insufficienza Renale Progressiva (PIRP) registry since 2005 and were followed up until 2013. Relative survival was the ratio of survival observed in CKD patients to the expected survival of the general population. Multivariate parametric survival analysis was used to identify factors predicting excess mortality. The relative survival of CKD patients at 9 years was 0.708. Survival was significantly lower in CKD patients with cardiovascular comorbidities, proteinuria, diabetes, anemia and high phosphate levels and in advanced CKD stages, males, older patients and those who underwent dialysis. Relative survival is a viable method to determine mortality attributable to CKD. Study limitations are that patients are representative only of CKD patients followed by nephrologists and that our follow-up duration may be relatively short as a model for mortality.

[Uric acid, the kidney and cardiovascular mortality]. / Acido Urico, Rene e Rischio Cardiovascolare.

Hyperuricemia is one of the many metabolic changes that occur during the course of chronic kidney disease (CKD). Even though it is clear its genesis of high uric acid levels (decreased renal clearance, overproduction, summation of both factors), we do not know the significance with regard to its effects on the cardiovascular (CV) system. On the other hand, the exact role of hyperuricemia in the general population it is not even established . In the general population, many studies have shown a strong correlation between uric acid levels and CV morbidity and mortality. However there are many researches that suggest a role of innocent bystander of uric acid, even in presence of elevated serum levels. Recently, there is an accumulation of evidence that emphasize a close link between uric acid and CV disease, at least in the field of CKD. In the patient population participating to the PIRP project (Prevention of Progressive Renal Failure of the Emilia-Romagna Region), we have seen, even with multivariate analysis, an independent role of high levels of uric acid concerning both, the occurrence of CV events and CV mortality.

Successful resumption of epoetin alfa after rituximab treatment in a patient with pure red cell aplasia.

An 80-year-old man with chronic renal failure (CRF) had pure red cell aplasia (PRCA) 9 months after starting the subcutaneous administration of recombinant human erythropoietin alfa (rHuEPO-alpha). Owing to the advanced renal failure, conventional immunosuppressive therapies were not practicable. It was decided to administer rituximab (4 cycles of 375 mg/m2/wk). PRCA was treated successfully with rituximab. The administration of rHuEPO-alpha then was resumed via the intravenous route with a satisfactory correction of anemia (12 months after the EPO-alpha rechallenge the patient is still transfusion independent). To the authors' knowledge, this is the first report of (1) a successful treatment with rituximab with CD20 depletion in a CRF patient with PRCA and (2) a successful intravenous resumption of the same rHuEPO-alpha.

Acute renal failure in a young woman with Fisher-Evans' syndrome.

A young female with Fisher-Evans' syndrome and a previous melanoma developed acute renal failure with generalized lymphoadenopathy and fever. The appearance of renal lesions is common in the course of several hematological disorders, but is unusual in Fisher-Evans' syndrome. Fisher-Evans' syndrome, defined as Coombs' positive hemolytic anemia and immune thrombocytopenia, is more frequently associated with the other autoimmune diseases, but not with renal involvement. In our case report, having excluded amyloidosis, myeloma, interstitial nephritis and sepsis, the rapid involvement of renal function with enlarged renal size seemed to suggest renal lymphoma. However, the lack of a monoclonal T-lymphocyte population in the renal tissue and peripheral blood, along with a clinical course characterized by a rapid reversibility of acute renal failure made this diagnosis rather an unlikely one. Polyclonal lymphocyte infiltration in a patient with a persistent autoimmune disease made us suspect a hyperimmune reaction. This syndrome is a non-neoplastic proliferation of B-cells involving an exaggeration of lymphocyte transformation. However, the clinical course is progressive and fatal, and can trigger a lymphoproliferative systemic disease. In our patient, two elements led us to suspect it was not a typical hyperimmune syndrome: first, polyclonal lymphocytes had massively infiltrated the kidney and, secondly, the clinical outcome was extremely favorable. Therefore, we were faced with an "atypical" and "singular" hyperimmune reaction with renal involvement, polyclonal proliferation of T-lymphocytes that had exhausted itself over time. Infective or toxic agents or drugs such as cyprofloxacin could have triggered the phenomenon, in the presence of a favorable condition such as Fisher-Evans' syndrome.