Long-term efficacy and safety of SARS-CoV-2 vaccination in patients with chronic kidney disease, on dialysis or after kidney transplantation: a national prospective observational cohort study.

BACKGROUND: COVID-19 is associated with increased morbidity and mortality in patients with chronic kidney disease (CKD) stages G4-G5, on dialysis or after kidney transplantation (kidney replacement therapy, KRT). SARS-CoV-2 vaccine trials do not elucidate if SARS-CoV-2 vaccination is effective in these patients. Vaccination against other viruses is known to be less effective in kidney patients. Our objective is to assess the efficacy and safety of various types of SARS-CoV-2 vaccinations in patients with CKD stages G4-G5 or on KRT. METHODS: In this national prospective observational cohort study we will follow patients with CKD stages G4-G5 or on KRT (n = 12,000) after SARS-CoV-2 vaccination according to the Dutch vaccination program. Blood will be drawn for antibody response measurements at day 28 and month 6 after completion of vaccination. Patient characteristics and outcomes will be extracted from registration data and questionnaires during 2 years of follow-up. Results will be compared with a control group of non-vaccinated patients. The level of antibody response to vaccination will be assessed in subgroups to predict protection against COVID-19 breakthrough infection. RESULTS: The primary endpoint is efficacy of SARS-CoV-2 vaccination determined as the incidence of COVID-19 after vaccination. Secondary endpoints are the antibody based immune response at 28 days after vaccination, the durability of this response at 6 months after vaccination, mortality and (serious) adverse events. CONCLUSION: This study will fulfil the lack of knowledge on efficacy and safety of SARS-CoV-2 vaccination in patients with CKD stages G4-G5 or on KRT. TRIAL REGISTRATION: The study protocol has been registered in clinicaltrials.gov ( NCT04841785 ). Current knowledge about this subject COVID-19 has devastating impact on patients with CKD stages G4-G5, on dialysis or after kidney transplantation. Effective SARS-CoV-2 vaccination is very important in these vulnerable patient groups. Recent studies on vaccination in these patient groups are small short-term studies with surrogate endpoints. Contribution of this study Assessment of incidence and course of COVID-19 after various types of SARS-CoV-2 vaccination during a two-year follow-up period in not only patients on dialysis or kidney transplant recipients, but also in patients with CKD stages G4-G5. Quantitative analysis of antibody response after SARS-CoV-2 vaccination and its relationship with incidence and course of COVID-19 in patients with CKD stages G4-G5, on dialysis or after kidney transplantation compared with a control group. Monitoring of (serious) adverse events and development of anti-HLA antibodies. Impact on practice or policy Publication of the study design contributes to harmonization of SARS-CoV-2 vaccine study methodology in kidney patients at high-risk for severe COVID-19. Data on efficacy of SARS-CoV-2 vaccination in patients with CKD will provide guidance for future vaccination policy.

Expanding the clinical spectrum of self-limiting, rare Kikuchi disease - A case with overwhelming multi-organ involvement.

Kikuchi disease is a rare disorder with an unknown pathogenesis and a typically self-limiting natural course in predominantly previously healthy young women. Here we present a 54-year-old woman suffering from an overwhelming presentation of Kikuchi disease, associated with haemophagocytic syndrome, liver cell necrosis and nephrotic syndrome. She recovered fully without immunosuppressive treatment. This case report adds to the already broad clinical spectrum of Kikuchi disease described in literature. Awareness among physicians of the full clinical spectrum of Kikuchi disease and the self-limiting nature of this syndrome leads to a good diagnostic approach and may prevent initiation of longstanding immunosuppressive therapy.

Safety and long-term effects of renal denervation: Rationale and design of the Dutch registry.

BACKGROUND: Percutaneous renal denervation (RDN) has recently been introduced as a treatment for therapy-resistant hypertension. Also, it has been suggested that RDN may be beneficial for other conditions characterised by increased sympathetic nerve activity. There are still many uncertainties with regard to efficacy, safety, predictors for success and long-term effects. To answer these important questions, we initiated a Dutch RDN registry aiming to collect data from all RDN procedures performed in the Netherlands. METHODS: The Dutch RDN registry is an ongoing investigator-initiated, prospective, multicentre cohort study. Twenty-six Dutch hospitals agreed to participate in this registry. All patients who undergo RDN, regardless of the clinical indication or device that is used, will be included. Data are currently being collected on eligibility and screening, treatment and follow-up. RESULTS: Procedures have been performed since August 2010. At present, data from 306 patients have been entered into the database. The main indication for RDN was hypertension (n = 302, 99%). Patients had a mean office blood pressure of 177/100 (±29/16) mmHg with a median use of three (range 0-8) blood pressure lowering drugs. Mean 24-hour blood pressure before RDN was 157/93 (±18/13) mmHg. RDN was performed with different devices, with the Simplicity™ catheter currently used most frequently. CONCLUSION: Here we report on the rationale and design of the Dutch RDN registry. Enrolment in this investigator-initiated study is ongoing. We present baseline characteristics of the first 306 participants.

Antiproteinuric efficacy of verapamil in comparison to trandolapril in non-diabetic renal disease.

BACKGROUND: Non-dihydropyridine calcium antagonists such as verapamil are equally effective in reducing proteinuria as ACE inhibitors in hypertensive patients with diabetic nephropathy. To date it is unknown whether verapamil elucidates such an antiproteinuric capacity in non-diabetic renal disease. METHODS: We performed a double-blind, placebo-controlled, random cross-over study which compared the antiproteinuric effect of 6 weeks treatment with verapamil SR (360 mg) to that of the ACE inhibitor trandolapril (4 mg), and their fixed combination vera/tran (180 mg verapamil SR and 2 mg trandolapril) in 11 non-diabetic patients with proteinuria of 6.6 (5.1-8.8) g/day, a creatinine clearance of 87 (74-106) ml/min, and a 24-h blood pressure of 136/85 (126/76-157/96) mmHg at baseline. RESULTS: Twenty-four-hour mean arterial pressure did not change during verapamil, whereas both trandolapril and vera/tran induced a significant reduction in MAP. Verapamil showed no significant effects on renal haemodynamics. Trandolapril and vera/tran did not significantly change GFR, but ERPF increased and FF decreased during both treatments (P<0.05). The antiproteinuric response of verapamil was significantly less compared to that of trandolapril and vera/tran (-12% (-17/-1) vs -51% (-56/-25) and -41% (-50/-19) respectively). The blood pressure and antiproteinuric response during verapamil tended to be greater in hypertensive patients than in normotensive patients, although this difference was not significant. Baseline blood pressure was related to the change in blood pressure during verapamil (r = -0.70; P < 0.02). CONCLUSIONS: The antiproteinuric and antihypertensive response of verapamil is less than that of the ACE inhibitor trandolapril in patients with non-diabetic renal disease. In contrast to the antiproteinuric response of trandolapril, the antiproteinuric reponse of verapamil seems to be completely dependent from effective blood pressure reduction. The fixed combination of verapamil and ACE inhibition at half doses has similar effects as ACE inhibition at full dose.

A comparison of analytic procedures for measurement of fractional dextran clearances.

Fractional dextran clearances have been extensively used to study glomerular size selectivity. We report on an analysis of different laboratory procedures involved in measuring fractional dextran clearances. The deproteinization of plasma samples by 20% trichloroacetic acid (TCA) revealed a protein contamination of 0.2% +/- 0.3%, whereas both 5% TCA and zinc sulfate deproteinization revealed a significantly higher remaining sample protein content (2.5% +/- 0.4% and 3.4% +/- 0.1%, respectively). Only zinc sulfate revealed incomplete deproteinization of urine samples (0.6% +/- 0.2%). Dextran recovery in plasma and urine supernatants was significantly lower after 5% TCA and zinc sulfate deproteinization when compared with 20% TCA deproteinization. Gel permeation chromatography (GPC) and high-performance liquid chromatography (HPLC) showed a variance of calibration smaller than 5% over 1 year. The use of 3 different sets of standard dextrans revealed significant differences in calibration. GPC and HPLC followed by anthrone assay showed a comparable variance in dextran concentration in plasma, from 3 to 6 nm (14% to 25%), whereas the variance in urine was lower for the GPC and anthrone assay, especially from 5.4 to 6 nm (23% to 43% versus 50% to 78%). HPLC and online refractometry showed the lowest variance of dextran concentration in plasma, from 3 to 6 nm (<4%), and in urine, from 3 to 5.2 nm (<7%), whereas it showed a higher variance in urine, from 5.4 to 6 nm, in comparison with GPC and HPLC with the anthrone assay. The GPC and anthrone assay revealed higher fractional dextran clearances in comparison with the HPLC and anthrone assay in healthy subjects (3 to 5.4 nm) as well as in patients with nondiabetic proteinuria (4.2 to 5.8 nm), and lower clearances in patients from 3 to 3.4 nm. The HPLC and anthrone assay revealed higher clearances in comparison with HPLC and online refractometry in healthy subjects (3.6 to 5.4 nm) and in patients (3.6 to 5.2 nm). The GPC and anthrone assay revealed characteristic differences in fractional dextran clearances between healthy subjects and patients. The HPLC and anthrone assay showed no significant differences between both groups, whereas HPLC and online refractometry showed only an increased clearance of dextrans from 4.6 to 5.2 nm in patients. Fractional clearances of dextran 5.6 nm as estimated by all 3 dextran assays were not significantly related to the fractional immunoglobulin G clearance or the immunoglobulin-to-albumin clearance index in our patients. Quantitative and qualitative differences in fractional dextran clearances may be induced by differences in laboratory procedures. We recommend sample preparation by 20% TCA deproteinization, frequent calibration with 1 set of dextran standards with low polydispersity, size-exclusion chromatography by GPC, and dextran detection by anthrone assay for optimal measurement of fractional dextran clearances. Even with such an approach, however, the variability in the measurement remains extremely high in the important range of dextrans greater than 5 nm.

The blunting of the antiproteinuric efficacy of ACE inhibition by high sodium intake can be restored by hydrochlorothiazide.

BACKGROUND: Dietary sodium restriction enhances the antiproteinuric and blood pressure lowering effect of ACE inhibition. In clinical practice, however, long-term compliance to a low-sodium diet may be difficult to obtain. We therefore investigated whether the blunting of the antiproteinuric and blood pressure lowering efficacy of ACE inhibition by high sodium intake can be restored by the addition of a diuretic. PATIENTS AND METHODS: Seven proteinuric patients with non-diabetic renal disease on chronic ACE inhibition were studied during three consecutive 4-week periods: low sodium (50 mmol/day), high sodium (200 mmol/day) and high sodium plus hydrochlorothiazide (50 mg o.i.d.). RESULTS: During low sodium intake proteinuria was 3.1 (0.7-5.2) g/day, during high sodium intake proteinuria increased to 4.5 (1.6-9.2) g/day (P < 0.05). Interestingly, addition of hydrochlorothiazide again reduced proteinuria to 2.8 (0.6-5.8) g/day (P < 0.05). Mean arterial blood pressure was 89 (84-96), 98 (91-104) and 89 (83-94) mmHg (P < 0.05) during the three periods, respectively. CONCLUSION: Addition of hydrochlorothiazide can overcome the blunting of the therapeutic efficacy of ACE inhibition on proteinuria and blood pressure by a high sodium intake.

Is the antiproteinuric response to inhibition of the renin-angiotensin system less effective during the night?

BACKGROUND: In glomerular disease proteinuria usually has a circadian pattern with maximum excretion during the day. Blockade of the renin-angiotensin system (RAS) results in a 50% reduction of proteinuria as measured in 24-h urine collections. We questioned whether anti-proteinuric treatment by blockade of the RAS is as effective during the day as during the night. METHODS: We analysed data from two intervention studies on proteinuria in patients with non-diabetic renal disease. In the first study, six hospitalized patients (proteinuria 5.8 +/- 2.9 g/day) were treated with the renin-inhibitor remikiren 600 mg o.d. during 8 days. In the second study eight ambulant patients (proteinuria 7.5 +/- 2.7 g/day) were treated during 6 weeks with the ACE-inhibitor trandolapril 4 mg o.d. Urine was collected in a day- and in a night-time portion. RESULTS: Daytime proteinuria declined from 0.29 +/- 0.15 to 0.22 +/- 0.11 g/h (P < 0.05) during remikiren and from 0.33 +/- 0.14 to 0.16 +/- 0.08 g/h (P < 0.05) during trandolapril. Night-time proteinuria, however, was not significantly reduced from 0.23 +/- 0.11 to 0.19 +/- 0.11 g/h during remikiren and from 0.29 +/- 0.17 to 0.20 +/- 0.12 g/h during trandolapril. Both interventions effectively lowered blood pressure during the day as well as the night. CONCLUSION: In both studies relative nocturnal therapy resistance to the antiproteinuric effect of RAS blockade was found, despite 24-h efficacy of blood pressure effect. This may have clinical relevance because it contributes to rest-proteinuria and thus may affect long term renal function outcome. It may be worthwhile to explore alternative therapeutic regimens to improve the nocturnal antiproteinuric response.

Measurement of glomerular charge selectivity in non-diabetic renal disease.

BACKGROUND: Until now, the renal clearance index of IgG to IgG4 (IgG/IgG4) as well as pancreatic to salivary amylase (PA/SA) were separately used as parameters of renal charge selectivity in diabetic and non-diabetic albuminuria. The suitability of the IgG index may be questioned because urinary loss of IgG rather reflects a size selective defect. In contrast, the amylase index seems more appropriate to reflect renal charge selectivity because its molecular size is comparable to albumin. We questioned whether IgG/IgG4 and PA/SA reflect renal charge selectivity in a comparable way in subjects with non-diabetic albuminuria over a wide range. METHODS: Renal fractional clearances of albumin, IgG, IgG4, PA and SA were estimated from ambulatory 24-h urine samples in 12 subjects with normo-albuminuria (UAE 4 [3-17] micrograms/min), six with micro-albuminuria (UAE: 147[36-200] micrograms/min), and 20 with macro-albuminuria (UAE: 2301 [608-13611] micrograms/min). RESULTS: Macro-albuminuria is associated with a reduced IgG/IgG4 and PA/SA, whereas micro-albuminuria is only associated with a reduced IgG/IgG4 compared to normo-albuminuria. A reduction of IgG/IgG4 (r = -0.75, P < 0.001) and PA/SA (r = -0.52, P < 0.001) correlates with an increased albuminuria. In addition, IgG/IgG4 correlates with PA/SA in the total population (r = 0.49, P < 0.01). IgG/IgG4 (r = 0.51, P < 0.05) correlates with the size selective index IgG/albumin in an opposite way to PA/SA (r = -0.52, P < 0.05) in 20 subjects with macro-albuminuria. Multiple regression analysis revealed IgG clearance to be the variable which contributes to the variance of albuminuria clearance for the greater part in our population. CONCLUSION: Both charge selective indices do not appear to correlate in micro-albuminuria. In addition, the presence of a size selective defect has a opposing effect on both charge selective indices. Although the reduction of IgG/IgG4 and PA/SA with increasing albuminuria suggests a progressive charge selective defect, albuminuria in our population is almost entirely explained by urinary loss of IgG. These data seriously question whether either one or both charge selective indices IgG/IgG4 and PA/SA do specifically reflect glomerular charge selectivity.

Blood pressure reduction initiates the antiproteinuric effect of ACE inhibition.

Several observations question the role of blood pressure and renal hemodynamic changes in the long-term antiproteinuric effect of ACE inhibition. To differentiate blood pressure and renal effects in the initial antiproteinuric response, the placebo-controlled acute effects of the ACE inhibitor enalaprilat (10 mg i.v.) on blood pressure, renal hemodynamics, and proteinuria were compared with those of nitroprusside in nine patient with non-diabetic proteinuria. In addition, we studied whether an exogenous angiotensin II infusion reverse the initial enalaprilat-induced antiproteinuric response. Enalaprilat and nitroprusside reduced MAP by -11.3 +/- 2.4% and -14.1 +/- 2.3%, respectively, whereas only enalaprilat showed renal hemodynamic effects, reflected by an increase in ERPF of 18.4 +/- 5.4% and a decrease in FF of -17.1 +/- 2.6%. Despite the contrasting renal hemodynamic profiles, enalaprilat (-10.6 +/- 4.8%) and nitroprusside (-12.8 +/- 5.1% equally decreased proteinuria. Exogenous infusion of angiotensin II completely reversed the blood pressure reduction and renal efferent vasodilatation induced by enalaprilat. proteinuria also increased by 13.1 +/- 7.8% to placebo level, albeit statistically non-significant. We conclude that the initial antiproteinuric effect of ACE inhibition appears to be mediated by blood pressure reduction and does not require its specific renal hemodynamic effect. Further studies should clarify whether the renal efferent vasodilatation during ACE inhibition is required to gradually induce renal structural changes that prevent the abundant passage of proteins.

Antiproteinuric effect of blood-pressure-lowering agents: a meta-analysis of comparative trials.

Whether ACE inhibitors (ACEi) differ from other antihypertensives in their efficacy to lower proteinuria is controversial. We therefore performed a meta-analysis of articles on this subject. The secondary objective in our meta-analysis was to study whether there is any difference between diabetic and non-diabetic patients in antiproteinuric response to blood pressure reduction. To identify all articles we performed a computer search using the bibliographic databases. To minimize publication bias, only trials in which a direct comparison was made between an ACEi and another antihypertensive were included. Studies performed both in diabetic and in non-diabetic patients were eligible. Included were 41 studies, comprising 1124 patients, of which 558 had non-diabetic renal disease. The mean antiproteinuric effect of ACEi was significantly greater than that of their comparator drugs: -39.9% (95% confidence interval: -42.8 to 36.8%) versus -17.0% (-19.0 to -15.1%) respectively (difference 24% (19.5 to 28.6%)). The blood-pressure-lowering effect was equal: -12.0% (-12.8 to -11.2%) versus -11.4% (-11.7 to -11.1%) respectively (difference -0.8% (-1.8 to 0.2%)). Thus it may be concluded that ACEIs confer an antiproteinuric effect beyond that attributable to their blood-pressure-lowering effect. A wide interstudy variation in antiproteinuric response to non-ACEI antihypertensives was observed. Multiple variable regression analysis was performed to assess which factors may explain this heterogeneity. From the comparator drugs, the class was of no importance: calcium-channel antagonists (CCA), beta-blockers, and a rest group of other drug types showed a similar response. Patient characteristics such as initial GFR and blood pressure partly explained the variation in response, but most of it appeared dependent on the blood pressure reduction achieved. Furthermore the type of CCA is of importance, with nifedipine having the least effect. A significantly greater antiproteinuric effect of 'non-ACEI' antihypertensives was found in diabetic patients compared to non-diabetics. However, this coincided with a greater blood pressure reduction in diabetics. Adjusted for differences in blood pressure control, diabetics showed even a slightly lesser antiproteinuric response to non-ACEI antihypertensive compared to non-diabetics.

Proteinuria: a risk factor for pregnancy-related renal function decline in primary glomerular disease?

Pregnancy may be followed by a postpartum acceleration of renal function loss in patients with renal disease. We retrospectively analyzed the effects of pregnancy on progressive renal function decline, and the risk factors for an acceleration, in a group of 19 renal disease patients with 30 pregnancies and a group of 31 patients who did not become pregnant after onset of glomerular disease. The rate of renal function loss was calculated for each patient by linear regression on reciprocal serum creatinine values over 11 years' follow-up. Multiple regression analysis showed that both pregnancy (P = 0.03) and initial proteinuria (P = 0.005) were independently related with the rate of renal function loss. Such a relation could not be observed with histologic diagnosis, and initial age, renal function, blood pressure, and serum albumin. Further analysis showed that 10 of 30 pregnancies are followed by a predefined acceleration of renal function loss. These pregnancies were preceded and complicated by a higher proteinuria (4.1 v 1.7 g/d, P < 0.005; and 3.6 v 2.1 g/d, P < 0.05, respectively) compared with the other 20 pregnancies that are not followed by such an acceleration. In conclusion, patients with primary glomerular disease complicated by substantial proteinuria are at risk for acceleration of renal function decline after pregnancy.