Canadian Society of Nephrology Commentary on the 2012 KDIGO Clinical Practice Guideline for Glomerulonephritis: Management of Nephrotic Syndrome in Children

Current Understanding of Nephrotic Syndrome in Children

Nephrotic syndrome in children is mostly idiopathic in origin. About 90% of patients respond to corticosteroids; 80-90% have at least one relapse and 3-10% become corticosteroid resistant after the initial response. A kidney biopsy is seldom indicated for diagnosis except in patients with atypical presentation or corticosteroid resistance. For those in remission, the risk of relapse is reduced by the administration of daily low dose corticosteroids for 5-7 days at the onset of an upper respiratory infection. Some patients may continue having relapses through adult life. Many country-specific practice guidelines have been published, which are very similar with clinically insignificant differences.

Tacrolimus Population Pharmacokinetic Model in Adult Chinese Patients with Nephrotic Syndrome and Dosing Regimen Identification Using Monte Carlo Simulations

BACKGROUND

The study aimed to establish a population pharmacokinetic (PPK) model of tacrolimus for Chinese patients with nephrotic syndrome using the patient's genotype and Wuzhi capsule dosage as the main test factors.

METHODS

Ninety-six adult patients with nephrotic syndrome, who were receiving tacrolimus treatment, were enrolled. A nonlinear mixed-effects model was used to determine the influencing factors of interindividual tacrolimus metabolism variation and establish a PPK model. To optimize the tacrolimus dosage, 10,000 Monte Carlo simulations were performed.

RESULTS

The 1-chamber model of first-order absorption and elimination was the most suitable model for the data in this study. The typical population tacrolimus clearance (CL/F) value was 16.9 L/h. The percent relative standard error (RSE%) of CL/F was 12%. Increased Wuzhi capsule and albumin doses both decreased the tacrolimus CL/F. In CYP3A5 homozygous mutation carriers, the CL/F was 39% lower than that of carriers of the wild-type and heterozygous mutation. The tacrolimus CL/F in patients who were coadministered glucocorticoids was 1.23-fold higher than that of the control. According to the patient genotype and combined use of glucocorticoids, 26 combinations of Wuzhi capsule and tacrolimus doses were matched. The Monte Carlo simulation identified the most suitable combination scheme.

CONCLUSIONS

An improved tacrolimus PPK model for patients with nephrotic syndrome was established, and the most suitable combination of Wuzhi capsule and tacrolimus doses was identified, thus, facilitating the selection of a more economical and safe administration regimen.

Treatment of idiopathic nephrotic syndrome with two steroid dosing regimens - one-year observational study

Introduction

The aim of the study was to compare the first year of disease in children with idiopathic nephrotic syndrome (INS) treated according to two prednisone dosing regimens: a weight-based schedule (2 mg/kg/24 h in the 1^st month, 2 mg/kg/48 h in the 2^nd month, with dose tapering during the following 4 months), and a body surface area (BSA)-based schedule (60 mg/m²/24 h in the 1^st month, 40 mg/m²/48 h in the 2^nd month, with dose tapering during the following 4 months).

Material and methods

In 2 groups of children treated with weight- and BSA-based regimens (20 patients, 3.13 ±1.01 years, treated in 2010-2013 and 20 patients, 5.13 ±2.86 years, treated in 2014-2016) clinical and anthropometrical parameters, number of INS relapses, total prednisone dose (mg/kg/year), and steroid adverse effects were compared during the first year of disease.

Results

Children treated with the weight-based steroid regimen received a higher total annual prednisone dose (259.06 ±79.54 vs. 185.83 ±72.67 mg/kg/24 h, p = 0.004) and had a shorter (though not significantly) period without prednisone (38.25 ±55.83 vs. 75.90 ±73.06 days, p = 0.062) compared to patients treated with the BSA-based regimen. There was no difference in number of relapses between groups (2.20 ±1.64 vs. 1.60 ±1.67, p = 0.190) but more patients relapsed in the weight-based group (19/20 vs. 13/20, p = 0.044). No differences in Z-score values of height, weight, and body mass index (BMI) were observed. No steroid-related adverse events were noted except for arterial hypertension (4/20 vs. 5/20 patients, p = 1.000).

Conclusions

The BSA-based regimen of prednisone dosing in children with INS reduces exposure to steroids and risk of relapse, as well as increases days off steroids in the first year compared to the weight-based regimen with a high second-month dose.

Dose tailoring of tacrolimus based on a non-linear pharmacokinetic model in children with refractory nephrotic syndrome

The population pharmacokinetics (PPK) of tacrolimus (TAC) in children with refractory nephrotic syndrome (RNS) have not been well-characterized. This study aimed to investigate the significant factors affecting the TAC PPK characteristics of children with RNS and to optimize the dosing regimen. A total of 494 concentrations from 108 children were obtained from routine therapeutic drug monitoring between 2016 and 2018. Information regarding the demographic features, laboratory test results, genetic polymorphisms of CYP3A5 (rs776746) and co-therapy medications were collected. PPK analysis was performed using the nonlinear mixed-effects modelling (NONMEM) software and two modelling strategies (the linear one-compartment model and nonlinear Michaelis-Menten model) were evaluated and compared. CYP3A5 genotype, weight, daily dose of TAC and daily dose of diltiazem were retained in the final linear model. The absorption rate constant (Ka) was set at 4.48 h^-1 in the linear model, and the apparent clearance (CL/F) and volume of distribution (V/F) in the final linear model were 14.2 L/h and 172 L, respectively. CYP3A5 genotype, weight and daily dose of diltiazem were the significant factors retained in the final nonlinear model. The maximal dose rate (V_max) and the average steady-state concentration at half-Vmax (K_m) in the final nonlinear model were 2.15 mg/day and 0.845 ng/ml, respectively. The nonlinear model described the pharmacokinetic data of TAC better than the linear model in children with RNS. A dosing regimen was proposed based on weight, CYP3A5 genotype and daily dose of diltiazem according to the final nonlinear PK model, which may facilitate individualized drug therapy with TAC.

Focal Segmental Glomerulosclerosis in Paediatric Population of South Punjab Pakistan: A Tertiary Care Hospital Experience

Objectives:

To find out frequency, clinicopathological features, response of treatment and outcome among children with primary focal segmental glomerulosclerosis (FSGS).

Methods:

This retrospective, non-interventional medical charts review study was conducted from a period of January 2011 to January 2020 at Pediatric Department of Nishtar Medical University Hospital, Multan, Pakistan. During the nine years study period, children of both genders, aged less than 16 years, with renal biopsies proven FSGS were included. Patient’s demographic along with clinical and laboratory data, urine dipstick for proteinuria, renal functions, 24 hours urinary protein and ultrasonography findings of kidneys, ureters and bladder (KUB) were noted from case records. Response rates of various treatment options and their outcome like remission, partial remission, no remission with stable kidney disease & no remission with progression of kidney disease were noted.

Results:

During the study duration, out of 307 renal biopsies performed in glomerulonephritis cases, 124 (40.4%) had primary FSGS. In 124 primary FSGS cases, mean age was 8.83±3.05 years while most of the children, 70 (56.5%) were above 10 years of age. Majority of the cases, 64 (51.6%) were male. Mean follow up duration was noted to be 28.35+18.47 months. Most of the cases, 68 (54.8%) were found to have complete remission, 22 (17.7%) partial remission while 11 (8.9%) progressed to ESKD.

Conclusions:

Among children, frequency of primary FSGS was high at our setting. Most of the cases achieved sustained remission rates with the help of immunosuppressive drugs. Cyclosporine and tacrolimus were found to be the most effective drugs.

Podocytopathies

Podocytopathies are kidney diseases in which direct or indirect podocyte injury drives proteinuria or nephrotic syndrome. In children and young adults, genetic variants in >50 podocyte-expressed genes, syndromal non-podocyte-specific genes and phenocopies with other underlying genetic abnormalities cause podocytopathies associated with steroid-resistant nephrotic syndrome or severe proteinuria. A variety of genetic variants likely contribute to disease development. Among genes with non-Mendelian inheritance, variants in APOL1 have the largest effect size. In addition to genetic variants, environmental triggers such as immune-related, infection-related, toxic and haemodynamic factors and obesity are also important causes of podocyte injury and frequently combine to cause various degrees of proteinuria in children and adults. Typical manifestations on kidney biopsy are minimal change lesions and focal segmental glomerulosclerosis lesions. Standard treatment for primary podocytopathies manifesting with focal segmental glomerulosclerosis lesions includes glucocorticoids and other immunosuppressive drugs; individuals not responding with a resolution of proteinuria have a poor renal prognosis. Renin-angiotensin system antagonists help to control proteinuria and slow the progression of fibrosis. Symptomatic management may include the use of diuretics, statins, infection prophylaxis and anticoagulation. This Primer discusses a shift in paradigm from patient stratification based on kidney biopsy findings towards personalized management based on clinical, morphological and genetic data as well as pathophysiological understanding.

Tacrolimus treatment in childhood refractory nephrotic syndrome: A retrospective study on efficacy, therapeutic drug monitoring, and contributing factors to variable blood tacrolimus levels

Tacrolimus, an immunosuppressive drug, was recommended by the 2012 KDIGO guidelines to treat nephrotic syndrome (NS) in children and adults. However, it has high interpatient pharmacokinetic variability and exposure levels should be monitored, although there are no specified target concentrations. This retrospective study aimed to review efficacy and safety after concomitant treatment with tacrolimus and prednisone, and to identify factors that contribute to the variable blood-trough-concentration-to-dose (C₀/Dose) ratio in children with refractory NS (RNS). A 6-month therapy induced complete or partial remission in 95% of patients. One-year follow-up indicated a high remission rate and low nephrotoxicity. Under maintenance dosages, approximately 95% of the C₀ values were 2-7 ng/mL. Body weight (BW), age, CYP3A5 polymorphisms were the factors affecting the C₀/Dose ratio. The C₀/Dose ratio in patients with a BW of <20 kg was 1.5-fold than that in patients with BW of ≥40 kg. Moreover, the C₀/Dose ratio in patients aged 1-≤6 and 6-≤12 years was significantly lower than that in patients aged 12-≤18 years, by 25% and 48%, respectively. There were no significant association between CYP3A5 genotyping and C₀/Dose ratio in younger children (1-≤6 years), rather than older children (6-≤18 years). In conclusion, routine CYP3A5 genotyping should be considered in children aged over 6 years and exposure levels (C₀) of 2-7 ng/mL may be feasible when tacrolimus is combined with low-dose prednisone to treat childhood RNS.

Association of low birth weight and prematurity with clinical outcomes of childhood nephrotic syndrome: a prospective cohort study

BACKGROUND

Low birth weight (LBW)/prematurity have been proposed as risk factors for the development of kidney disease in adulthood. Whether there is an association between LBW/prematurity and poor renal outcomes in childhood onset nephrotic syndrome remains unknown.

METHODS

Children with nephrotic syndrome diagnosed between 1 and 18 years of age were followed prospectively from 1996 to 2016 at The Hospital for Sick Children (N = 377). LBW/prematurity was defined as birth weight < 2500 g or gestational age < 36 weeks. Normal birth weight (NBW) was defined as birth weight ≥ 2500 g. Measures evaluating clinical course of nephrotic syndrome include initial steroid-resistant nephrotic syndrome (SRNS), time to first relapse, and frequently relapsing nephrotic syndrome. Kaplan-Meier survival analysis, logistic regression, and Cox proportional hazards regression were used to determine the association of LBW/prematurity with clinical outcomes.

RESULTS

Median birth weights in LBW/premature (n = 46) and NBW (n = 331) children were 2098 g (interquartile range [IQR] 1700-2325 g) and 3317 g (IQR 2977-3685 g), respectively. Odds of having SRNS were 3.78 (95% confidence interval [CI] 1.28-11.21) times higher among LBW/premature children than NBW children. An 8% decrease in odds of developing SRNS was observed for every 100 g increase in birth weight (adjusted odds ratio [OR] 0.92; 95% CI 0.86-0.98). Median time to first relapse did not differ (hazard ratio [HR] 0.89; 95% CI 0.53-1.16).

CONCLUSIONS

LBW/premature children were more likely to develop SRNS but did not have a difference in time to first relapse with NBW children. Understanding the impact and mechanism of birth weight and steroid-resistant disease needs further study.

Outcomes of Older Patients (≥60 years) with New-Onset Idiopathic Nephrotic Syndrome Receiving Immunosuppressive Regimen: A Multicentre Study of 116 Patients

Because of its rarity, renal presentation and outcomes of idiopathic nephrotic syndrome (INS; minimal changes disease or focal and segmental glomerulosclerosis) has poorly been described in elderly patients, precluding an individualized therapy procedure. Whether immunosuppressive regimens formerly designed in children and young adults are safe and efficient in elderly remains elusive. In a large multicentric retrospective study that included 116 patients with INS and onset ≥ 60 years of age, we showed that cumulative incidence of renal response was 95% after frontline therapy, with an age-dependent median time-to-response (60 days before 70 years of age at the onset vs. 120 days after; p = 0.03). Cumulative incidence of relapse was 90% at 7 years, with relapse occurring continuously over time. After a median follow-up of 34 months (IQR (12; 57)), 7 patients had died (6%) and 5 reached end-stage renal disease. Complications were highly prevalent: diabetes mellitus (23.3%), hypertension (24.1%), infection requiring hospitalization (21.6%) and acute kidney injury (9.5%). Thus, in older patients with INS and receiving steroids, renal response is delayed and relapse is the rule. Alternative immunosuppressive regimens, including B-cells depleting agents as frontline therapy, should be tested in this subset of patients to improve the mid- to long-term outcomes.

Efficacy and safety of mycophenolate mofetil versus levamisole in frequently relapsing nephrotic syndrome: an open-label randomized controlled trial

Both levamisole and mycophenolate mofetil (MMF) prevent relapses in patients with frequently relapsing nephrotic syndrome; however, their efficacy has not been compared prospectively. This single-center, randomized, open-label trial enrolled 149 children ages 6-18 years with frequently relapsing or steroid-dependent nephrotic syndrome. Participants were randomized in a 1:1 ratio to receive therapy with MMF (750-1000 mg/m² daily) or levamisole (2-2.5 mg/kg on alternate days) for 1 year; prednisolone was discontinued by 2-3 months. In intention-to-treat analyses, the frequency of relapse was similar between participants treated with MMF and levamisole (mean difference -0.29 relapses/patient-year; 95% confidence interval -0.65, 0.08). Relapse rates declined to almost one-third of baseline for both treatment groups. Therapy with MMF was not superior to levamisole in terms of the proportions of participants with sustained remission (40.8% vs. 34.2%), frequent relapses (14.5% vs. 16.4%), or treatment failure, a composite outcome of frequent relapses, steroid resistance, or significant steroid toxicity (15.8% vs. 20.6%). These outcomes were also similar in time to event analyses. Changes in anthropometry and blood pressure were similar between the groups, and the rates of adverse effects were low in both groups. Flow cytometry in 32 participants demonstrated similar proportions of B cells and CD4+, CD8+, T helper (Th)1, Th2, Th17, and T regulatory (Treg) cells during follow-up. Therapy with MMF was not superior to levamisole in the frequency of relapses, likelihood of sustained remission or corticosteroid sparing in children with frequently relapsing or steroid-dependent nephrotic syndrome. Registration CTRI/2012/02/002394.

Cyclophosphamide versus cyclosporine A therapy in steroid-resistant nephrotic syndrome: a retrospective study with a mean 5-year follow-up

Objective

To compare the clinical efficacy of cyclophosphamide (CTX) and cyclosporine A (CSA) in initial treatment of children with steroid-resistant nephrotic syndrome (SRNS).

Methods

Prospectively maintained databases were reviewed to retrospectively compare two cohorts with SRNS that received peroral administration of 2 to 2.5 mg/kg/d CTX for 3 to 6 months or 1 to 5 mg/kg/d CSA for 2 years until the primary analysis cut-off date during 2007 to 2011. The time to first on-study relapse of SRNS was the primary endpoint. The effective rate was the second endpoint.

Results

A total of 127 children with SRNS were included (CTX-treated cohort: n = 62; CSA-treated cohort: n = 65), with a mean 5-year follow-up. CTX-treated children showed a significantly delayed time to first on-study relapse of SRNS compared with CSA-treated children (hazard ratio 0.66, 95% confidence interval 0.32–1.75). The relapse rate (rate/year) in CTX-treated children (1.1 ± 0.1) at the 24-month follow-up was significantly higher than that with CSA (0.4 ± 0.2). This difference persisted until the final follow-up.

Conclusions

CSA is associated with a significantly lower relapse rate and significantly higher effective rate compared with CTX, especially in children with minimal change disease.

Does cyclophosphamide still play a role in glomerular diseases?

Cyclophosphamide is a prodrug that is converted to inactive carboxy-cyclophosphamide, acrolein and phosphoramide mustard, an agent that adds alkyl groups to oxygen and nitrogen atoms of guanine, one of the four nitrogen bases that form the DNA nucleotides, causing DNA cross-links and introducing DNA breaks. These cytotoxic and mutagenic effects mainly occur in proliferating cells. Repair mechanisms may prevent DNA damage in quiescent cells, but they may be insufficient to contrast the side effects of cyclophosphamide if high doses of the drug are used. Most adverse events are dose- and age-dependent. Phosphoramide mustard can cause bone marrow toxicity, gonadal toxicity, and may favor the development of leukemia, bladder cancer and other types of malignancy. Acrolein can produce hemorrhagic cystitis and even bladder fibrosis when given for prolonged periods. A number of precautional measures should be taken to prevent these untoward events. In particular, long-term administration and high doses of cyclophosphamide should be avoided whenever possible. Today the indications to cyclophosphamide in glomerular diseases are more restricted than in the past, but the drug is still used as a steroid-sparing agent in steroid-sensitive minimal change disease and focal segmental glomerulosclerosis. In membranous nephropathy, cyclophosphamide, alternated or associated with corticosteroids, proved to be beneficial in obtaining remission of nephrotic syndrome and preserving renal function. Cyclophosphamide is considered as a first-line treatment for rapidly progressive glomerulonephritis and the hectic phases of lupus nephritis. In conclusion, cyclophosphamide is a cheap drug that may be useful in a number of glomerular diseases but it may lead to severe side effects. A close monitoring of blood count and clinical conditions, as well as low cumulative doses of cyclophosphamide are strongly recommended when using the drug in patients with renal diseases.

Elevated urinary monocyte chemoattractant protein-1 levels in children with Henoch-Schonlein purpura nephritis

BACKGROUND

Chemokine monocyte chemoattractant protein-1 (MCP-1) has been proved as a potential urinary biomarker in nephropathies. The aim of this study was to investigate the urinary monocyte chemoattractant protein-1 (MCP-1) levels and clinical significance in Henoch-Schonlein purpura (HSP) children with and without nephritis and determine the association of MCP-1 with proteinuria.

METHODS

A total of 261 HSP children-with or without nephritis-and 84 healthy control children were enrolled in this study. Of these, 126 HSP nephritis (HSPN) children were subdivided into three groups according to total urine protein in 24 h (TUP): Group A, mild proteinuria group with TUP <25 mg/kg; Group B, moderate proteinuria group with TUP ≥25 mg/kg and <50 mg/kg; Group C, severe proteinuria group with TUP ≥50 mg/kg. Urinary MCP-1 levels were determined by ELISA. Levels of serum creatinine (Cr), blood urea nitrogen (BUN), urinary α₁-micro globulin (α₁-MG), micro-albumin (mAlb), immunoglobulin G (IgG), transferrin (TRF) and TUP were performed to determine their associations with MCP-1.

RESULTS

Urinary MCP-1 was significantly higher in HSPN group in comparison with HSP group and controls (P < 0.05), but no significant difference was found between the HSP group and the healthy group (P > 0.05). The levels of urinary MCP-1 increased in parallel to the enhancement of total urine protein in 24 h in HSPN patients. There were statistically significant differences among these three groups of HSPN children (p < 0.05). Urinary MCP-1 correlated positively with urinary α₁-MG, mAlb, IgG, TRF and TUP in HSPN, whereas no correlation was observed with serum Cr and BUN.

CONCLUSIONS

MCP-1 was elevated in children with HSPN and correlated with proteinuria. Urinary MCP-1 could be used as a suitable, non-invasive biomarker to provide valuable information not only for the diagnosis of HSPN, but also for evaluation of severity of renal damage.

Focal segmental glomerulosclerosis in children complicated by posterior reversible encephalopathy syndrome

An uncommon side effect of cyclosporine A (CsA) use is posterior reversible encephalopathy syndrome (PRES). PRES usually develops because of disturbed capacity of posterior cerebral blood flow to autoregulate an acute rise in blood pressure. We present the case of a 10-year-old girl who was previously diagnosed in our department with focal segmental glomerulosclerosis. She was treated with CsA and developed seizures, progressive loss of consciousness, and visual disturbance on the 7th day of treatment. Brain magnetic resonance imaging showed degeneration of white matter with diffuse demyelination in the parietal and posterior occipital lobes, consistent with the diagnosis of PRES. Cases of PRES reported in children are usually secondary to immunosuppressive therapy in oncological and haematological diseases. Our case is the fifth reported case of focal segmental glomerulosclerosis in children treated with CsA and complicated by PRES. Rapid recognition of PRES and stopping neurotoxic therapy early are essential for a good prognosis.

Indications for kidney biopsy in idiopathic childhood nephrotic syndrome

BACKGROUND

Most cases of childhood nephrotic syndrome (NS) are due to minimal change disease (MCD), while a minority of children have focal segmental glomerulosclerosis (FSGS) and an unfavorable clinical course, requiring a kidney biopsy to confirm diagnosis. We hypothesized that clinical characteristics at diagnosis and initial response to corticosteroid treatment accurately predict FSGS and can be used to guide consistent practice in the indications for kidney biopsy.

METHODS

This was a case control study (1990-2012). Inclusion criteria included age 1-17 years, meeting the diagnostic criteria for NS, and having biopsy-proven FSGS or MCD. Clinical characteristics at diagnosis included age, kidney function [estimated glomerular filtration rate (eGFR)], hypertension, hematuria, nephritis (reduced eGFR, hematuria, hypertension), and response to steroids.

RESULTS

From a total of 169 children who underwent kidney biopsy for NS we included 65 children with MCD and 22 with FSGS for analysis. There were no significant between-group differences in age, sex, or eGFR at the time of diagnosis. The FSGS group had a higher proportion of hypertension (40 vs. 15%; p = 0.02), hematuria (80 vs. 47%; p = 0.01), and nephritis (22 vs. 2%; p = 0.004) and was more likely to be steroid resistant after 6 weeks of treatment than the MCD group (67 vs. 19%; p < 0.001). As predictors of FSGS, hematuria had a high sensitivity of 0.80 [95% confidence interval (CI) 0.56-0.93] and low specificity of 0.53 (95% CI 0.39-0.66), nephritis had a low sensitivity of 0.22 (95% CI 0.07-0.48) and high specificity of 0.98 (95% CI 0.88-0.99), and steroid resistance had a low sensitivity of 0.67 (95% CI 0.43-0.85) and high specificity of 0.81 (95% CI 0.68-0.90). The combination of steroid resistance after 6 weeks of therapy and/or nephritis at diagnosis yielded the optimal sensitivity and specificity at 0.80 (95% CI 0.56-0.93) and 0.75 (95% CI 0.60-0.86), respectively, confirmed by the highest receiver operator characteristic area under the curve of 0.77.

CONCLUSION

Steroid resistance after 6 weeks of therapy and/or nephritis at initial presentation is an accurate predictor of FSGS in children with NS and will be used as the indication for kidney biopsy in our newly developed clinical pathway. This approach will maximize the yield of diagnostic FSGS biopsies while minimizing the number of unnecessary MCD biopsies.

Setting New Directions for Research in Childhood Nephrotic Syndrome: Results From a National Workshop

Background:

We report on the proceedings of a national workshop held in Canada with the aims to identify priorities for research in childhood nephrotic syndrome and to develop a national strategy to address these priorities.

Methods:

A diverse group of participants attended the meeting, including patients, family members, researchers, and health care providers. We used small group discussions to explore priorities as perceived by patients and families and by health care providers and researchers.

Results:

Research evaluating glucocorticoid minimization or glucocorticoid-sparing regimens was a consistent theme in the patient and family discussion group. Families also indicated the need for precise prognostic information at diagnosis, more information to help them choose the best available therapy, and more resources for disease management. Health care providers emphasized the importance of better disease characterization including genotyping and phenotyping patients, better understanding the pathogenesis, and the need of providing targeted therapy and precise prognostic information.

Conclusions:

These priorities will inform the development and future directions of the Canadian Childhood Nephrotic Syndrome (CHILDNEPH) project, a national research initiative to improve care and outcomes of patients with childhood onset nephrotic syndrome.

Mycophenolate mofetil is inferior to tacrolimus in sustaining remission in children with idiopathic steroid-resistant nephrotic syndrome

Studies of nephrotic syndrome show that substitution of calcineurin inhibitors by mycophenolate mofetil (MMF) enables sustained remission and corticosteroid sparing and avoids therapy associated adverse effects. However, controlled studies in patients with steroid resistance are lacking. Here we examined the effect of switching from therapy with tacrolimus to MMF on disease course in an open-label, one-to-one randomized, controlled trial on children (one to 18 years old), recently diagnosed with steroid-resistant nephrotic syndrome, at a referral center in India. Following six months of therapy with tacrolimus, patients with complete or partial remission were randomly assigned such that 29 received MMF while 31 received tacrolimus along with tapering prednisolone on alternate days for 12 months. On intention-to-treat analyses, the proportion of patients with a favorable outcome (sustained remission, infrequent relapses) at one year was significantly lower (44.8%) in the MMF group than in the tacrolimus group (90.3%). The incidence of relapses was significantly higher for patients treated with MMF than tacrolimus (mean difference: 1.05 relapses per person-year). While there was no difference in the proportion of patients with sustained remission, the risk of recurrence of steroid resistance was significantly higher for patients receiving MMF compared to tacrolimus (mean difference: 20.7%). Compared to tacrolimus, patients receiving MMF had a significantly (71%) lower likelihood of a favorable outcome and significantly increased risk of treatment failure (frequent relapses, steroid resistance). Thus, replacing tacrolimus with MMF after six months of tacrolimus therapy for steroid-resistant nephrotic syndrome in children is associated with significant risk of frequent relapses or recurrence of resistance. These findings have implications for guiding the duration of therapy with tacrolimus for steroid-resistant nephrotic syndrome.

Rituximab in Minimal Change Disease: Mechanisms of Action and Hypotheses for Future Studies

Treatment with rituximab, a monoclonal antibody against the B-lymphocyte surface protein CD20, leads to the depletion of B cells. Recently, rituximab was reported to effectively prevent relapses of glucocorticoid-dependent or frequently relapsing minimal change disease (MCD). MCD is thought to be T-cell mediated; how rituximab controls MCD is not understood. In this review, we summarize key clinical studies demonstrating the efficacy of rituximab in idiopathic nephrotic syndrome, mainly MCD. We then discuss immunological features of this disease and potential mechanisms of action of rituximab in its treatment based on what is known about the therapeutic action of rituximab in other immune-mediated disorders. We believe that studies aimed at understanding the mechanisms of action of rituximab in MCD will provide a novel approach to resolve the elusive immune pathophysiology of MCD.

Recent Advances in Treatments of Primary Focal Segmental Glomerulosclerosis in Children

Focal segmental glomerulosclerosis (FSGS) is a nephrotic syndrome. Up to around 80% of cases of primary FSGS are resistant to steroid treatment. A large proportion of patients with steroid-resistant FSGS progress to end-stage renal disease. The purpose of treatment is to obtain a complete remission of proteinuria, a necessary step that precedes improved renal survival and reduces the risk of progression to chronic kidney disease. When this is not possible, the secondary goal is a partial remission of proteinuria. Reduction or remission of proteinuria is the most important factor predictive of renal survival. We will review the current updated strategies for treatment of primary FSGS in children, including traditional therapies consisting of corticosteroids and calcineurin inhibitors and novel therapies such as rituximab, abatacept, adalimumab, and fresolimumab.

Should we stop dosing steroids per body surface area for nephrotics?

In this edition of Pediatric Nephrology, Vaishnavi Raman et al. have published an open-labeled randomized clinical trial of 100 children with idiopathic nephrotic syndrome who were allocated either a body weight- or body surface area-based prednisolone dosing for a duration of 12 weeks. The authors used Kaplan-Meier analysis for comparison of the time to remission. They also compared the relapse rate and found no difference. This editorial discusses the strengths of the current study as well some limitations. The inclusion of relapsing patients in the study protocol is problematic. The follow-up period of only 6 months forms another limitation. No subgroup analysis by age was performed. This editorial also highlights the lack of correlation between steroid dose and steroid exposure and the need for considering the age dependency (ontogeny) of drug disposition. Finally, the need for adherence to CONSORT criteria for reporting randomized controlled clinical trials is emphasized.

Childhood nephrotic syndrome in the 21st century: What's new?

Childhood nephrotic syndrome is a condition managed by general paediatricians and paediatric nephrologists. Whether treating a first presentation or a relapse, the clinician requires expertise in order to minimise the risk of serious complications and optimise long-term care. Indeed, many children suffer a difficult relapsing course in their disease, warranting consideration of second-line therapies. The last two decades have witnessed a growing knowledge of the condition and increased complexity of diagnostic and therapeutic options, which poses a challenge for the general paediatrician, given the condition's relative rarity in daily practice. This review aims to familiarise the reader with some of the most important recent developments and particularly to provide an insight into what management options are available and when it may be appropriate to seek advice from a nephrologist.

Pathophysiology, Evaluation, and Management of Edema in Childhood Nephrotic Syndrome

Generalized edema is a major presenting clinical feature of children with nephrotic syndrome (NS) exemplified by such primary conditions as minimal change disease (MCD). In these children with classical NS and marked proteinuria and hypoalbuminemia, the ensuing tendency to hypovolemia triggers compensatory physiological mechanisms, which enhance renal sodium (Na(+)) and water retention; this is known as the "underfill hypothesis." Edema can also occur in secondary forms of NS and several other glomerulonephritides, in which the degree of proteinuria and hypoalbuminemia, are variable. In contrast to MCD, in these latter conditions, the predominant mechanism of edema formation is "primary" or "pathophysiological," Na(+) and water retention; this is known as the "overfill hypothesis." A major clinical challenge in children with these disorders is to distinguish the predominant mechanism of edema formation, identify other potential contributing factors, and prevent the deleterious effects of diuretic regimens in those with unsuspected reduced effective circulatory volume (i.e., underfill). This article reviews the Starling forces that become altered in NS so as to tip the balance of fluid movement in favor of edema formation. An understanding of these pathomechanisms then serves to formulate a more rational approach to prevention, evaluation, and management of such edema.

The Canadian Society of Nephrology methods in developing and adapting clinical practice guidelines: a review

INTRODUCTION

The Canadian Society of Nephrology (CSN) was established to promote the highest quality of care for patients with renal diseases and to encourage research related to the kidney and its disorders. The CSN Clinical Practice Guideline (CPG) Committee develops guidelines with clear recommendations to influence physicians' practice and improve the health of patients with kidney disease in Canada.

REVIEW

In this review we describe the CSN process in prioritizing CPGs topics. We document the CSN experience using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. We then detail the CSN process in developing de novo CPGs and in adapting existing CPGs and developing accompanying commentaries. We also discuss challenges faced during this process and suggest solutions. Furthermore, we summarize the CSN effort in disseminating and implementing their guidelines. Additionally, we describe recent development and partnerships that allow evaluation of the effect of the CSN guidelines and commentaries.

CONCLUSION

The CSN follows a comprehensive process in identifying priority areas to be addressed in CPGs. In 2010, the CSN adopted GRADE, which enhanced the rigor and transparency of guideline development. This process focuses on systematically identifying best available evidence and carefully assessing its quality, balancing benefits and harms, considering patients' and societies' values and preferences, and when possible considering resource implications. Recent partnership allows wider dissemination and implementation among end users and evaluation of the effects of CPG and commentaries on the health of Canadians.