Interventions for atypical haemolytic uraemic syndrome.

BACKGROUND: Atypical haemolytic uraemic syndrome (aHUS) is a rare disorder characterised by thrombocytopenia, microangiopathic haemolytic anaemia, and acute kidney injury. The condition is primarily caused by inherited or acquired dysregulation of complement regulatory proteins with ~40% of those affected aged < 18 years. Historically, kidney failure and death were common outcomes, however, improved understanding of the condition has led to discovery of novel therapies. OBJECTIVES: To evaluate the benefits and harms of interventions for aHUS. SEARCH METHODS: We searched the Cochrane Kidney and Transplant Register of Studies for randomised controlled studies (RCTs) up to 3 September 2020 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. MEDLINE(OVID) 1946 to 27 July 2020 and EMBASE (OVID) 1974 to 27 July 2020 were searched for non-RCTs. SELECTION CRITERIA: All randomised and non-randomised clinical trials comparing an intervention with placebo, an intervention with supportive therapy, or two or more interventions for aHUS were included. Given the rare nature of the condition in question, prospective single-arm studies of any intervention for aHUS were also included. DATA COLLECTION AND ANALYSIS: Two authors independently extracted pre-specified data from eligible studies and evaluated risk of bias using a newly developed tool based on existing Cochrane criteria. As statistical meta-analysis was not appropriate, qualitative analysis of data was then performed. MAIN RESULTS: We included five single-arm studies, all of which evaluated terminal complement inhibition for the treatment of aHUS. Four studies evaluated the short-acting C5 inhibitor eculizumab and one study evaluated the longer-acting C5 inhibitor ravulizumab. All included studies within the review were of non-randomised, single-arm design. Thus, risk of bias is high, and it is challenging to draw firm conclusions from this low-quality evidence. One hundred patients were included within three primary studies evaluating eculizumab, with further data reported from 37 patients in a secondary study. Fifty-eight patients were included in the ravulizumab study. After 26 weeks of eculizumab therapy there were no deaths and a 70% reduction in the number of patients requiring dialysis. Complete thrombotic microangiopathic (TMA) response was observed in 60% of patients at 26 weeks and 65% at two years. After 26 weeks of ravulizumab therapy four patients had died (7%) and complete TMA response was observed in 54% of patients. Substantial improvements were seen in estimated glomerular filtration rate and health-related quality of life in both eculizumab and ravulizumab studies. Serious adverse events occurred in 42% of patients, and meningococcal infection occurred in two patients, both treated with eculizumab. AUTHORS' CONCLUSIONS: When compared with historical data, terminal complement inhibition appears to offer favourable outcomes in patients with aHUS, based upon very low-quality evidence drawn from five single-arm studies. It is unlikely that an RCT will be conducted in aHUS and therefore careful consideration of future single-arm data as well as longer term follow-up data will be required to better understand treatment duration, adverse outcomes and risk of disease recurrence associated with terminal complement inhibition.

Renal Biopsy Prognostic Findings in Children With Atypical Hemolytic Uremic Syndrome.

BACKGROUND: The aim of this study was to investigate the histopathological findings in kidney biopsies in children with atypical hemolytic uremic syndrome (aHUS) and to determine whether specific pathological findings in aHUS have a prognostic value. METHODS: Renal biopsy specimens of 29 patients who were recorded in the national Turkish aHUS registry database were available for review. Histopathological findings were compared with the clinical and laboratory features at the presentation and the final outcome. RESULTS: The mean age at presentation and follow-up period was 4.9 ± 3.9 and 3.9 ± 3.0 years, respectively. The median time interval from the first symptom to biopsy was 10 days. Vascular thrombosis and interstitial fibrosis were significantly related to chronic kidney disease (CKD) requiring dialysis or kidney transplantation during follow-up (5.6-fold, for both). Glomerular necrosis, cortical necrosis, and glomerular sclerosis were markedly associated with CKD without dialysis (6.2-fold, 13.3-fold, and 8.8-fold, respectively). However, presence of endothelial swelling, subendothelial widening, and fragmented erythrocytes was found to be correlated with a favorable final outcome. CONCLUSIONS: Presence of vascular thrombosis, cortical necrosis, and glomerular sclerosis in histopathological evaluation correlated with developing CKD. Chronic changes in the interstitial compartment were also related to poor prognosis, a finding that has been shown for the first time in pediatric aHUS cases.

Atypical and secondary hemolytic uremic syndromes have a distinct presentation and no common genetic risk factors.

Secondary hemolytic uremic syndrome (HUS) is a heterogeneous group of thrombotic microangiopathies associated with various underlying conditions. Whether it belongs to the spectrum of complement-mediated HUS remains controversial. We analysed the presentation, outcome, and frequency of complement gene rare variants in a cohort of 110 patients with secondary HUS attributed to drugs (29%), autoimmune diseases (24%), infections (17%), malignancies (10%), glomerulopathies (9%), extra-renal organ transplantation (8%), and pancreatitis (3%). The frequency of complement gene rare variants was similar in patients with secondary HUS (5%) and in healthy individuals (6% and 8% in French and European controls, respectively). At diagnosis, 40% of patients required dialysis and 18% had neurological manifestations. Fifty percent of patients received plasmatherapy and 35% were treated with eculizumab. Haematological and complete renal remission was achieved in 80% and 24% of patients, respectively. Thirty-nine percent of patients progressed to chronic kidney disease (stages 3-4) and an additional 37% reached end-stage renal disease. Eleven percent of patients died, most often from complications of the underlying cause of HUS. Only one patient experienced an HUS relapse. Patients treated with eculizumab presented with more severe HUS and were more likely to require dialysis at the time of diagnosis as compared to patients not treated with eculizumab. Rates of hematological remission, chronic kidney disease (stages 3-4), and end-stage renal disease were similar in the two groups. Secondary HUS is an acute nonrelapsing form of HUS, not related to complement dysregulation. The efficacy of eculizumab in this setting is not yet established.

Impact of hypertensive emergency and rare complement variants on the presentation and outcome of atypical hemolytic uremic syndrome.

A typical hemolytic uremic syndrome (aHUS) is a prototypic thrombotic microangiopathy attributable to complement dysregulation. Hypertensive emergency, characterized by elevation of systolic (>180 mmHg) or diastolic (>120 mmHg) blood pressure together with end-organ damage, can cause thrombotic microangiopathy which may mimic aHUS. We retrospectively evaluated the clinical, biological and complement genetic characteristics of 76 and 61 aHUS patients with and without hypertensive emergency, respectively. Patients with hypertensive emergency-aHUS were more frequently males, with neurological involvement, and a slightly higher hemoglobin level. At least one rare complement variant was identified in 51.3% (39/76) and 67% (41/61) patients with or without hypertensive emergency, respectively (P=0.06). In both groups, renal prognosis was severe with 23% and 40% of patients reaching end-stage renal disease after a 5-year follow-up (P=0.1). The 5-year renal survival was 77% in patients without hypertensive emergency or a complement variant, and below 25% in the three groups of patients with hypertensive emergency and/or a complement variant (P=0.02). Among patients without hypertensive emergency, the 5-year renal survival was 100% vs 40% in those treated or not with eculizumab, respectively (P<0.001). Conversely, the 5-year renal survival of patients with hypertensive emergency was 46% vs 23% in those treated or not with eculizumab, respectively (P=0.18). In conclusion, information on the presence or absence of hypertensive emergency and rare complement variants is essential to stratify the long-term renal prognosis of patients with aHUS.

Adverse outcomes in obstetric-atypical haemolytic uraemic syndrome: a case series analysis.

Objective: The aim of this case series is to raise awareness of obstetric-related atypical haemolytic uraemic syndrome (aHUS) amongst obstetricians and gynaecologists. Study design: Data from 20 consecutive patients, aged 19-38, with obstetric-aHUS manifestation during or immediately after pregnancy are reported. Patients were diagnosed and treatment was initiated between 2012 and 2016. Results: Presentation of aHUS was mainly preceded by preeclampsia and/or haemolysis, elevated liver enzymes and low platelet count syndrome, other obstetric complications, or by diarrhoea. Thrombotic microangiopathy (TMA) was evident in all patients with signs of microangiopathic haemolysis (sharp decline in haemoglobin; mean 67 g/L), elevated lactate dehydrogenase (LDH; mean 2953.1 U/L), schistocytosis, thrombocytopenia (mean platelet count 52.5 × 109/µL), and acute kidney injury (AKI) (hypercreatininaemia, mean 456.4 µmol/L; oliguria or anuria). The majority of patients (80%) initially presented with arterial hypertension. Diagnosis of obstetric-aHUS was complicated, as multiple organs were affected. Time taken to make the diagnosis of aHUS delayed the initiation of fresh-frozen plasma infusions and plasma exchange (80% of patients) and subsequent eculizumab treatment (40% of patients). Maternal mortality was high (35%) as was foetal mortality (25%). Conclusions: Obstetric-aHUS is a serious condition characterized by multiple organ failure (MOF) and a high mortality rate. Presentation of obstetric-aHUS is preceded by various precipitating factors, suggesting pregnancy complications, and not the pregnancy per se, often induce aHUS in women with a genetic predisposition to its development. A delay in the correct diagnosis and initiation of the most effective treatment can have serious consequences, reinforcing the need to raise awareness of obstetric-aHUS.

Extra-renal manifestations of atypical hemolytic uremic syndrome.

Atypical hemolytic uremic syndrome (aHUS) is a rare and complex disease resulting from abnormal alternative complement activation with a wide range of clinical presentations. Extra-renal manifestations of aHUS can involve many organ systems, including the peripheral and central nervous, gastrointestinal, cardiovascular, integumentary, pulmonary, as well as the eye. While some of these extra-renal manifestations occur in the acute phase of aHUS, some can also occur as long-term sequelae of unopposed complement activation. Extra-renal symptoms are observed in approximately 20% of patients with aHUS, with the incidence of specific organ system complications ranging from a few case reports to 50% of described patients. Careful monitoring for extra-renal involvement is critical in patients with aHUS, as prompt evaluation and management may decrease the risk of high morbidity and mortality associated with aHUS.

Clinical and genetic predictors of atypical hemolytic uremic syndrome phenotype and outcome.

Atypical hemolytic uremic syndrome (aHUS) is a rare, genetic, life-threatening disease. The Global aHUS Registry collects real-world data on the natural history of the disease. Here we characterize end-stage renal disease (ESRD)-free survival, the rate of thrombotic microangiopathy, organ involvement and the genetic background of 851 patients in the registry, prior to eculizumab treatment. A sex-specific difference was apparent according to age at initial disease onset as the ratio of males to females was 1.3:1 for childhood presentation and 1:2 for adult presentation. Complement Factor I and Membrane Cofactor Protein mutations were more common in patients with initial presentation as adults and children, respectively. Initial presentation in childhood significantly predicted ESRD risk (adjusted hazard ratio 0.55 [95% confidence interval 0.41-0.73], whereas sex, race, family history of aHUS, and time from initial presentation to diagnosis, did not. Patients with a Complement Factor H mutation had reduced ESRD-free survival, whereas Membrane Cofactor Protein mutation was associated with longer ESRD-free survival. Additionally extrarenal organ manifestations occur in 19%-38% of patients within six months of initial disease presentation (dependent on organ). Thus, our real-world results provide novel insights regarding phenotypic variables and genotypes on the clinical manifestation and progression of aHUS.

Atypical hemolytic uremic syndrome: A monocentric adult Tunisian study and review of literature.

Atypical hemolytic uremic syndrome (aHUS) is characterized by microvascular thrombosis resulting in thrombocytopenia, hemolytic anemia, and multiorgan dysfunction. It is associated with genetic or acquired disorders of regulatory components of the complement system. For our study, we collected data from 16 patients diagnosed with aHUS between January 2010 and January 2014. The mean age was 33.6 years. The female-to-male ratio was 3. The median follow-up duration was 27 ± 3.5 months. The most common clinical presentation was hypertension. Renal involvement was noted in all cases. Ten patients had extrarenal manifestations. Semi-quantitative dysfunction of the alternative pathway of complement was found in all cases. A genetic study was not available for our patients. During the acute stage, all patients received plasma therapy, and among them, seven required dialysis and five were still on dialysis at the time of discharge. One patient underwent renal transplantation. None of our patients received eculizumab perfusion. The renal survival was inversely correlated to young age (<30 years) (P = 0.001), presence of anti-factor H antibodies (P = 0.003) and serum creatinine at diagnosis >5 mg/dL (P = 0.02). Mortality rate was significantly correlated to young age (<30 years old) (P = 0.01). Collecting multicentric data on adult patients with aHUS will enable better characterization of the spectrum of adult aHUS in our country and the evaluation of current treatments and different outcomes.

Outcomes of patients with atypical haemolytic uraemic syndrome with native and transplanted kidneys treated with eculizumab: a pooled post hoc analysis.

Atypical haemolytic uraemic syndrome (aHUS) often leads to end-stage renal disease (ESRD) and kidney transplantation; graft loss rates are high due to disease recurrence. A post hoc analysis of four prospective clinical trials in aHUS was performed to evaluate eculizumab, a terminal complement inhibitor, in patients with native or transplanted kidneys. The trials included 26-week treatment and extension periods. Dialysis, transplant and graft loss were evaluated. Study endpoints included complete thrombotic microangiopathy (TMA) response, TMA event-free status, haematologic and renal parameters and adverse events. Of 100 patients, 74 had native kidneys and 26 in the transplant subgroup had a collective history of 38 grafts. No patients lost grafts and only one with pre-existing ESRD received a transplant on treatment. Efficacy endpoints were achieved similarly in both subgroups. After 26 weeks, mean absolute estimated glomerular filtration rate increased from baseline to 61 and 37 ml/min/1.73 m2 in native (n = 71; P < 0.0001) and transplanted kidney (n = 25; P = 0.0092) subgroups. Two patients (one/subgroup) developed meningococcal infections; both recovered, one continued therapy. Eculizumab was well tolerated. Eculizumab improved haematologic and renal outcomes in both subgroups. In patients with histories of multiple graft losses, eculizumab protected kidney function.

Transplant-associated thrombotic microangiopathy: opening Pandora's box.

Transplant-associated thrombotic microangiopathy (TA-TMA) is an early complication of hematopoietic cell transplantation (HCT). A high mortality rate is documented in patients who are refractory to calcineurin inhibitor cessation. Estimates of TA-TMA prevalence vary significantly and are higher in allogeneic compared with autologous HCT. Furthermore, our understanding of the pathophysiology that is strongly related to diagnosis and treatment options is limited. Recent evidence has linked TA-TMA with atypical hemolytic uremic syndrome, a disease of excessive activation of the alternative pathway of complement, opening the Pandora's box in treatment options. As conventional treatment management is highly inefficient, detection of complement activation may allow for early recognition of patients who will benefit from complement inhibition. Preliminary clinical results showing successful eculizumab administration in children and adults with TA-TMA need to be carefully evaluated. Therefore, realizing the unmet needs of better understanding TA-TMA in this complex setting, we aimed to summarize current knowledge focusing on (1) critical evaluation of diagnostic criteria, (2) epidemiology and prognosis, (3) recent evidence of complement activation and endothelial damage and (4) treatment options.

Turkish pediatric atypical hemolytic uremic syndrome registry: initial analysis of 146 patients.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a devastating disease with significant morbidity and mortality. Its genetic heterogeneity impacts its clinical presentation, progress, and outcome, and there is no consensus on its clinical management. METHODS: To identify the characteristics of aHUS in Turkish children, an industry-independent registry was established for data collection that includes both retrospective and prospective patients. RESULTS: In total, 146 patients (62 boys, 84 girls) were enrolled; 53 patients (36.3%) were less than 2 years old at initial presentation. Among the 42 patients (37.1%) whose mutation screening was complete for CFH, CFI, MCP, CFB, C3, DGKE, and CHFR5 genes, underlying genetic abnormalities were uncovered in 34 patients (80.9%). Sixty-one patients (41.7%) had extrarenal involvement. During the acute stage, 33 patients (22.6%) received plasma therapy alone, among them 17 patients (51.5%) required dialysis, and 4 patients (12.1%) were still on dialysis at the time of discharge. In total, 103 patients (70.5%) received eculizumab therapy, 16 of whom (15.5%) received eculizumab as a first-line therapy. Plasma therapy was administered to 84.5% of the patients prior to eculizumab. In this group, renal replacement therapy was administered to 80 patients (77.7%) during the acute period. A total of 3 patients died during the acute stage. A total of 101 patients (77.7%) had a glomerular filtration rate >90 mL/min/1.73 m2 at the 2-year follow-up. CONCLUSIONS: The Turkish aHUS registry will increase our knowledge of patients with aHUS who have different genetic backgrounds and will enable evaluation of the different treatment options and outcomes.

Headache prevalence following recovery from TTP and aHUS.

Thrombotic thrombocytopenia purpura (TTP) and atypical hemolytic uremic syndromes (aHUS) are distinct clinical disorders characterized by hemolytic anemia, thrombocytopenia, microthrombi, and end organ damage. TTP is characterized by a low ADAMTS13 activity level at diagnosis of <10 % ADAMTS13 activity, while aHUS is characterized as having >10 % ADAMTS13 activity. Despite clinical remission, survivors of thrombotic microangiopathy suffer significant comorbidity and decreased quality of life (QOL) than their healthy counterparts. The reason for this is unclear. Is it a lingering effect from their initial acute episode or ongoing subclinical injury/inflammation despite clinical remission? Common clinical complaints validated in practice include increased depression, deficits in memory, concentration, mood, and mental endurance. We suspect headaches may be an important clinical tool toward understanding patient morbidity and decreased QOL. To date, no studies report headache frequency or severity in this population. To answer this question, adult patients >3 months since their last acute episode of TTP or aHUS were approached to take a Headache Impact Test (HIT-6) survey. Between June 1, 2013 and May 30, 2014, 31 patients in remission (21 patients with prior TTP and 10 patients with prior aHUS) completed the HIT-6 survey. The survey scores were then compared to the HIT-6 normative population data established by Qualitymetric incorporated. Overall, TTP patients had a significantly higher average HIT-6 score of 59.9 compared to an average HIT-6 score of 51 seen in sex-matched controls (SD 9.6, p value 0.002). No significant difference was seen in the HIT-6 scores of aHUS patients. Of TTP patients studied, approximately 57 % (12/21) had three or more episodes and were >24 months since the last episode. The average time since last acute episode in TTP patients was 37.5 months. There was no significant correlation between TTP survivor HIT-6 scores and the number of prior episodes (1, 2, or >3) or timing from the last episode (3-6, 7-12, 13-24, or >24 months). About 19/21 (90 %) patients, who are TTP survivors, also had a normal ADAMTS13 activity level (>10 %) on the day of the survey. Our study suggests that headaches have significant impact on TTP survivors and should be followed in the clinical setting to prevent undue patient morbidity. Larger studies are needed to understand how headaches impact long-term survival and risk of relapse.