Rates of adverse clinical events in patients with chronic kidney disease: analysis of electronic health records from the UK clinical practice research datalink linked to hospital data.

BACKGROUND: Further understanding of adverse clinical event rates in patients with chronic kidney disease (CKD) is required for improved quality of care. This study described baseline characteristics, adverse clinical event rates, and mortality risk in patients with CKD, accounting for CKD stage and dialysis status. METHODS: This retrospective, noninterventional cohort study included data from adults (aged ≥ 18 years) with two consecutive estimated glomerular filtration rates of < 60 ml/min/1.73 m2, recorded ≥ 3 months apart, from the UK Clinical Practice Research Datalink of electronic health records obtained between January 1, 2004, and December 31, 2017. Select adverse clinical events, associated with CKD and difficult to quantify in randomized trials, were assessed; defined by Read codes and International Classification of Diseases, Tenth Revision codes. Clinical event rates were assessed by dialysis status (dialysis-dependent [DD], incident dialysis-dependent [IDD], or non-dialysis-dependent [NDD]), dialysis modality (hemodialysis [HD] or peritoneal dialysis [PD]), baseline NDD-CKD stage (3a-5), and observation period. RESULTS: Overall, 310,953 patients with CKD were included. Comorbidities were more common in patients receiving dialysis than in NDD-CKD, and increased with advancing CKD stage. Rates of adverse clinical events, particularly hyperkalemia and infection/sepsis, also increased with advancing CKD stage and were higher in patients on HD versus PD. Mortality risk during follow-up (1-5-year range) was lowest in patients with stage 3a NDD-CKD (2.0-18.5%) and highest in patients with IDD-CKD (26.3-58.4%). CONCLUSIONS: These findings highlight the need to monitor patients with CKD for comorbidities and complications, as well as signs or symptoms of clinical adverse events.

Prevalence of anaemia in adults with chronic kidney disease in a representative sample of the United States population: analysis of the 1999-2018 National Health and Nutrition Examination Survey.

Background: Population-based estimates of anaemia prevalence in patients with chronic kidney disease (CKD) vary, and data on the prevalence of severe anaemia of CKD are limited. This study examined the prevalence of anaemia and anaemia eligible for erythropoiesis-stimulating agent (ESA) treatment in patients with CKD in the USA. Methods: National Health and Nutrition Examination Survey (NHANES) data from 1999-2000 to 2017-18 were used to determine the prevalence of diagnosed anaemia (haemoglobin <12 g/dL in women; <13 g/dL in men) and anaemia eligible for ESA treatment (haemoglobin <10 g/dL) in survey participants aged ≥18 years with stage 3-5 non-dialysis-dependent CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2). The study objectives were to (i) obtain a more recent estimate of anaemia prevalence in patients with non-dialysis-dependent CKD and (ii) examine the characteristics of individuals with CKD and haemoglobin <10 g/dL. Results: Of 51 163 eligible NHANES participants, 2926 (5.7%) with stage 3-5 CKD were included. In all participants, the weighted prevalences of anaemia and haemoglobin <10 g/dL were 25.3% and 1.9%, respectively. Mean haemoglobin levels decreased numerically between 1999 and 2012 and remained stable thereafter. The prevalence of anaemia and haemoglobin <10 g/dL increased with advancing CKD stage. The odds of haemoglobin <10 g/dL were significantly higher in stage ≥3B versus 3A and in non-Hispanic Blacks versus other races. Conclusions: In our analysis, approximately 25% of individuals with stage 3-5 CKD in the USA had anaemia and approximately 2% had anaemia eligible for ESA treatment.

Changes in Iron Availability with Roxadustat in Nondialysis- and Dialysis-Dependent Patients with Anemia of CKD.

Background: Roxadustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, increases hemoglobin by stimulating erythropoietin synthesis and improving iron availability through facilitation of iron uptake and/or release from stores. In this exploratory analysis, we assessed the effect of roxadustat treatment on laboratory parameters related to iron metabolism in patients with anemia of chronic kidney disease (CKD). Methods: Data were pooled from pivotal, randomized, phase 3 roxadustat trials: three placebo-controlled, double-blind trials in nondialysis-dependent (NDD) CKD and three open-label, active-comparator (epoetin alfa) trials in dialysis-dependent (DD) CKD. In this exploratory analysis, mean changes from baseline in hemoglobin, iron parameters, and hepcidin, and intravenous (iv) iron use were evaluated. Pooled results in NDD CKD and DD CKD patients are reported. Results: Overall, 4277 patients with NDD CKD and 3890 patients with DD CKD were evaluated. Hemoglobin increases with roxadustat treatment were accompanied by increases in serum iron and total iron-binding capacity (TIBC) and decreases in serum ferritin and hepcidin from baseline through week 52. With epoetin alfa, the hemoglobin increase was accompanied by decreases in serum ferritin and hepcidin, but serum iron decreased, and there was no change in TIBC. With placebo, there were no changes in hemoglobin, iron parameters, or hepcidin. During treatment, iv iron use was reduced with roxadustat versus placebo and epoetin alfa. Conclusions: In patients with NDD CKD and DD CKD, roxadustat treatment is associated with increases in serum iron and TIBC, accompanied by reduced hepcidin and indicative of improved iron kinetics. Patients treated with roxadustat achieved target hemoglobin levels with less iv iron use versus comparators. Practitioners treating patients with anemia of CKD with roxadustat should consider its unique effects when interpreting iron parameters.

Iron Deficiency in Heart Failure and Effect of Dapagliflozin: Findings From DAPA-HF.

BACKGROUND: Iron deficiency is common in heart failure and associated with worse outcomes. We examined the prevalence and consequences of iron deficiency in the DAPA-HF trial (Dapagliflozin and Prevention of Adverse-Outcomes in Heart Failure) and the effect of dapagliflozin on markers of iron metabolism. We also analyzed the effect of dapagliflozin on outcomes, according to iron status at baseline. METHODS: Iron deficiency was defined as a ferritin level <100 ng/mL or a transferrin saturation <20% and a ferritin level 100 to 299 ng/mL. Additional biomarkers of iron metabolism, including soluble transferrin receptor, erythropoietin, and hepcidin were measured at baseline and 12 months after randomization. The primary outcome was a composite of worsening heart failure (hospitalization or urgent visit requiring intravenous therapy) or cardiovascular death. RESULTS: Of the 4744 patients randomized in DAPA-HF, 3009 had ferritin and transferrin saturation measurements available at baseline, and 1314 of these participants (43.7%) were iron deficient. The rate of the primary outcome was higher in patients with iron deficiency (16.6 per 100 person-years) compared with those without (10.4 per 100 person-years; P<0.0001). The effect of dapagliflozin on the primary outcome was consistent in iron-deficient compared with iron-replete patients (hazard ratio, 0.74 [95% CI, 0.58-0.92] versus 0.81 [95% CI, 0.63-1.03]; P-interaction=0.59). Similar findings were observed for cardiovascular death, heart failure hospitalization, and all-cause mortality. Transferrin saturation, ferritin, and hepcidin were reduced and total iron-binding capacity and soluble transferrin receptor increased with dapagliflozin compared with placebo. CONCLUSIONS: Iron deficiency was common in DAPA-HF and associated with worse outcomes. Dapagliflozin appeared to increase iron use but improved outcomes, irrespective of iron status at baseline. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03036124.

Roxadustat for Treating Anemia in Patients with CKD Not on Dialysis: Results from a Randomized Phase 3 Study.

BACKGROUND: Current anemia therapies for patients with non-dialysis-dependent CKD may require injection and medical visits. Roxadustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, stimulates erythropoiesis and improves iron homeostasis. METHODS: In this double-blind phase 3 study, we randomized patients with non-dialysis-dependent CKD stages 3-5 and hemoglobin <10.0 g/dl (1:1) to thrice-weekly 70-mg oral roxadustat or placebo. Doses were titrated throughout the study based on hemoglobin levels. The primary efficacy end point was mean change from baseline in hemoglobin averaged over weeks 28-52 versus placebo, irrespective of rescue therapy use. We assessed patients for adverse events. RESULTS: The study included 2781 patients, 1393 who received roxadustat and 1388 who received placebo. Mean baseline hemoglobin was 9.1 g/dl for both groups. The mean change in hemoglobin from baseline was 1.75 g/dl (95% confidence interval [95% CI], 1.68 to 1.81) with roxadustat versus 0.40 g/dl (95% CI, 0.33 to 0.47) with placebo, (P<0.001). Among 411 patients with baseline elevated high-sensitivity C-reactive protein, mean change in hemoglobin from baseline was 1.75 g/dl (95% CI, 1.58 to 1.92) with roxadustat versus 0.62 g/dl (95% CI, 0.44 to 0.80) with placebo, (P<0.001). Roxadustat reduced the risk of red blood cell transfusion by 63% (hazard ratio, 0.37; 95% CI, 0.30 to 0.44). The most common adverse events with roxadustat and placebo, respectively, were ESKD (21.0% versus 20.5%), urinary tract infection (12.8% versus 8.0%), pneumonia (11.9% versus 9.4%), and hypertension (11.5% versus 9.1%). CONCLUSIONS: Roxadustat effectively increased hemoglobin in patients with non-dialysis-dependent CKD and reduced the need for red blood cell transfusion, with an adverse event profile comparable to that of placebo. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Safety and Efficacy Study of Roxadustat to Treat Anemia in Patients With CKD, Not on Dialysis, NCT02174627.

Focal Segmental Glomerulosclerosis, Risk Factors for End Stage Kidney Disease, and Response to Immunosuppression.

Background: FSGS is a heterogeneic glomerular disease. Risk factors for kidney disease ESKD and the effect of immunosuppression treatment (IST) has varied in previously published cohorts. These cohorts were limited by relatively small case numbers, short follow-up, lack of racial/ethnic diversity, a mix of adult and pediatric patients, lack of renin-angiotensin-aldosterone system (RAAS) inhibition, or lack of subgroup analysis of IST. Methods: We compared demographics, clinical characteristics, histopathology, and IST to long-term renal survival in a large, ethnically diverse, adult cohort of 338 patients with biopsy-proven FSGS with long-term follow-up in the era of RAAS inhibition using data from the US Department of Defense health care network. Results: Multivariate analysis showed that nephrotic-range proteinuria (NRP), eGFR <60 ml/min per 1.73 m2, hypoalbuminemia, interstitial fibrosis and tubular atrophy, and interstitial inflammation at diagnosis and the absence of remission were all associated with worse long-term renal survival. IgM, C3, and a combination of IgM/C3 immunofluorescence staining were not associated with reduced renal survival. IST was not associated with improved renal survival in the whole cohort, or in a subgroup with NRP. However, IST was associated with better renal survival in a subgroup of patients with FSGS with both NRP and hypoalbuminemia and hypoalbuminemia alone. Conclusions: Our study suggests that IST should be reserved for patients with FSGS and nephrotic syndrome. It also introduces interstitial inflammation as a potential risk factor for ESKD and does not support the proposed pathogenicity of IgM and complement activation.

Detection of PLA2R Autoantibodies before the Diagnosis of Membranous Nephropathy.

BACKGROUND: Circulating serum autoantibodies against the M-type phospholipase A2 receptor (PLA2R-AB) are a key biomarker in the diagnosis and monitoring of primary membranous nephropathy (MN). However, little is known about the appearance and trajectory of PLA2R-AB before the clinical diagnosis of MN. METHODS: Using the Department of Defense Serum Repository, we analyzed PLA2R-AB in multiple, 1054 longitudinal serum samples collected before diagnosis of MN from 134 individuals with primary MN, 35 individuals with secondary MN, and 134 healthy volunteers. We evaluated the presence and timing of non-nephrotic range proteinuria (NNRP) and serum albumin measurements in relation to PLA2R-AB status. RESULTS: Analysis of PLA2R-AB in longitudinal serum samples revealed seropositivity in 44% (59 out of 134) of primary MN cases, 3% (one out of 35) of secondary MN cases, and in 0% of healthy controls. Among patients with MN, PLA2R-AB were detectable at a median of 274 days before renal biopsy diagnosis (interquartile range, 71-821 days). Approximately one third of the participants became seropositive within 3 months of MN diagnosis. Of the 21 individuals with documented prediagnostic NNRP, 43% (nine out of 21) were seropositive before NNRP was first documented and 28.5% (six out of 21) were seropositive at the same time as NNRP; 66% (39 out of 59) of those seropositive for PLA2R-AB had hypoalbuminemia present at the time antibody was initially detected. Twelve participants (20%) were seropositive before hypoalbuminemia became apparent, and eight participants (14%) were seropositive after hypoalbuminemia became apparent. CONCLUSIONS: Circulating PLA2R-AB are detectable months to years before documented NNRP and biopsy-proven diagnosis in patients with MN.

Survey of Kidney Biopsy Clinical Practice and Training in the United States.

BACKGROUND AND OBJECTIVES: Practicing clinical nephrologists are performing fewer diagnostic kidney biopsies. Requiring biopsy procedural competence for graduating nephrology fellows is controversial. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: An anonymous, on-line survey of all Walter Reed training program graduates (n=82; 1985-2017) and all United States nephrology program directors (n=149; August to October of 2017), regarding kidney biopsy practice and training, was undertaken. RESULTS: Walter Reed graduates' response and completion rates were 71% and 98%, respectively. The majority felt adequately trained in native kidney biopsy (83%), transplant biopsy (82%), and tissue interpretation (78%), with no difference for ≤10 versus >10 practice years. Thirty-five percent continued to perform biopsies (13% did ≥10 native biopsies/year); 93% referred at least some biopsies. The most common barriers to performing biopsy were logistics (81%) and time (74%). Program director response and completion rates were 60% and 77%. Seventy-two percent cited ≥1 barrier to fellow competence. The most common barriers were logistics (45%), time (45%), and likelihood that biopsy would not be performed postgraduation (41%). Fifty-one percent indicated that fellows should not be required to demonstrate minimal procedural competence in biopsy, although 97% agreed that fellows should demonstrate competence in knowing/managing indications, contraindications, and complications. Program directors citing ≥1 barrier or whose fellows did <50 native biopsies/year in total were more likely to think that procedural competence should not be required versus those citing no barriers (P=0.02), or whose fellows performed ≥50 biopsies (P<0.01). CONCLUSIONS: Almost two-thirds of graduate respondents from a single military training program no longer perform biopsy, and 51% of responding nephrology program directors indicated that biopsy procedural competence should not be required. These findings should inform discussion of kidney biopsy curriculum requirements.

PilN Binding Modulates the Structure and Binding Partners of the Pseudomonas aeruginosa Type IVa Pilus Protein PilM.

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that expresses type IVa pili. The pilus assembly system, which promotes surface-associated twitching motility and virulence, is composed of inner and outer membrane subcomplexes, connected by an alignment subcomplex composed of PilMNOP. PilM binds to the N terminus of PilN, and we hypothesize that this interaction causes functionally significant structural changes in PilM. To characterize this interaction, we determined the crystal structures of PilM and a PilM chimera where PilM was fused to the first 12 residues of PilN (PilM·PilN(1-12)). Structural analysis, multiangle light scattering coupled with size exclusion chromatography, and bacterial two-hybrid data revealed that PilM forms dimers mediated by the binding of a novel conserved motif in the N terminus of PilM, and binding PilN abrogates this binding interface, resulting in PilM monomerization. Structural comparison of PilM with PilM·PilN(1-12) revealed that upon PilN binding, there is a large domain closure in PilM that alters its ATP binding site. Using biolayer interferometry, we found that the association rate of PilN with PilM is higher in the presence of ATP compared with ADP. Bacterial two-hybrid data suggested the connectivity of the cytoplasmic and inner membrane components of the type IVa pilus machinery in P. aeruginosa, with PilM binding to PilB, PilT, and PilC in addition to PilN. Pull-down experiments demonstrated direct interactions of PilM with PilB and PilT. We propose a working model in which dynamic binding of PilN facilitates functionally relevant structural changes in PilM.

P. aeruginosa SGNH hydrolase-like proteins AlgJ and AlgX have similar topology but separate and distinct roles in alginate acetylation.

The O-acetylation of polysaccharides is a common modification used by pathogenic organisms to protect against external forces. Pseudomonas aeruginosa secretes the anionic, O-acetylated exopolysaccharide alginate during chronic infection in the lungs of cystic fibrosis patients to form the major constituent of a protective biofilm matrix. Four proteins have been implicated in the O-acetylation of alginate, AlgIJF and AlgX. To probe the biological function of AlgJ, we determined its structure to 1.83 Å resolution. AlgJ is a SGNH hydrolase-like protein, which while structurally similar to the N-terminal domain of AlgX exhibits a distinctly different electrostatic surface potential. Consistent with other SGNH hydrolases, we identified a conserved catalytic triad composed of D190, H192 and S288 and demonstrated that AlgJ exhibits acetylesterase activity in vitro. Residues in the AlgJ signature motifs were found to form an extensive network of interactions that are critical for O-acetylation of alginate in vivo. Using two different electrospray ionization mass spectrometry (ESI-MS) assays we compared the abilities of AlgJ and AlgX to bind and acetylate alginate. Binding studies using defined length polymannuronic acid revealed that AlgJ exhibits either weak or no detectable polymer binding while AlgX binds polymannuronic acid specifically in a length-dependent manner. Additionally, AlgX was capable of utilizing the surrogate acetyl-donor 4-nitrophenyl acetate to catalyze the O-acetylation of polymannuronic acid. Our results, combined with previously published in vivo data, suggest that the annotated O-acetyltransferases AlgJ and AlgX have separate and distinct roles in O-acetylation. Our refined model for alginate acetylation places AlgX as the terminal acetlytransferase and provides a rationale for the variability in the number of proteins required for polysaccharide O-acetylation.