Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits

High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic and pulse pressure) to date in over 1 million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also highlight shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future.

Multi-ethnic genome-wide association study for atrial fibrillation

Atrial fibrillation (AF) affects more than 33 million individuals worldwide1 and has a complex heritability2. We conducted the largest meta-analysis of genome-wide association studies (GWAS) for AF to date, consisting of more than half a million individuals, including 65,446 with AF. In total, we identified 97 loci significantly associated with AF, including 67 that were novel in a combined-ancestry analysis, and 3 that were novel in a European-specific analysis. We sought to identify AF-associated genes at the GWAS loci by performing RNA-sequencing and expression quantitative trait locus analyses in 101 left atrial samples, the most relevant tissue for AF. We also performed transcriptome-wide analyses that identified 57 AF-associated genes, 42 of which overlap with GWAS loci. The identified loci implicate genes enriched within cardiac developmental, electrophysiological, contractile and structural pathways. These results extend our understanding of the biological pathways underlying AF and may facilitate the development of therapeutics for AF.

Large-scale analyses of common and rare variants identify 12 new loci associated with atrial fibrillation

Atrial fibrillation affects more than 33 million people worldwide and increases the risk of stroke, heart failure, and death. Fourteen genetic loci have been associated with atrial fibrillation in European and Asian ancestry groups. To further define the genetic basis of atrial fibrillation, we performed large-scale, trans-ancestry meta-analyses of common and rare variant association studies. The genome-wide association studies (GWAS) included 17,931 individuals with atrial fibrillation and 115,142 referents; the exome-wide association studies (ExWAS) and rare variant association studies (RVAS) involved 22,346 cases and 132,086 referents. We identified 12 new genetic loci that exceeded genome-wide significance, implicating genes involved in cardiac electrical and structural remodeling. Our results nearly double the number of known genetic loci for atrial fibrillation, provide insights into the molecular basis of atrial fibrillation, and may facilitate the identification of new potential targets for drug discovery.

Rapid and accurate assessment of glomerular filtration rate in patients with renal transplants using serum cystatin C

BACKGROUND

Assessment of renal function in patients with renal transplants is of great importance. Various studies have reported cystatin C as an easily and rapidly assessable marker that can be used for accurate information on renal function impairment. To date, no study is available to define the role of cystatin C in patients with renal transplants.

METHODS

Thirty steady-state patients (50% male/50% female) with status post-kidney transplantation were studied. To assess renal function, cystatin C, creatinine clearance, serum creatinine, beta2-microglobulin (beta2M), and [125I]iothalamate clearance were determined. Correlations and non-parametric ROC curves for accuracy, using a cut-off glomerular filtration rate (GFR) of 60 ml/min, were obtained for the different markers allowing for calculations of positive predictive values (PPV), positive likelihood ratios (PLR), specificity and sensitivity, respectively. Further, to evaluate the usefulness of these markers for monitoring, intraindividual coefficients of variation (CVs) for cystatin C and creatinine measurements were compared in 85 renal transplant patients. Measurements consisted of at least six pairs of results, which were obtained at different time points during routine follow-up.

RESULTS

Cystatin C correlated best with GFR (r=0.83), whereas serum creatinine (r=0.67), creatinine clearance (r=0.57) and beta2M (r=0.58) all had lower correlation coefficients. The diagnostic accuracy of cystatin C was significantly better than serum creatinine (P=0.025), but did not differ significantly from creatinine clearance (P=0.76) and beta2M (P=0.43). At a cut-off of 1.64 mg/l, cystatin C has a PPV of 93%, PLR of 6.4, specificity 89% and sensitivity 70%, respectively. For beta2M, PPV 83%, PLR 1.7, specificity 67% and sensitivity 75% was seen at a cut-off of 3.57 mg/l. Accordingly, at a cut-off of 125 micromol/l for serum creatinine, a PPV 76%, PLR 1.4, specificity 44% and sensitivity 80% was revealed. Finally, at a cut-off of 66 ml/min/1.73 m2 for creatinine clearance, the following characteristics were found: PPV 94%, PLR 7.7, specificity 89% and sensitivity 85%. The intraindividual variation of creatinine was significantly lower than that of cystatin C (P<0.001). With increasing concentrations, their ratios of CV tended towards a value of 1, demonstrating identical variability at low GFR.

CONCLUSION

Together, our data show that in patients with renal transplants, cystatin C, in terms of PPV and PLR, has a similar diagnostic value as creatinine clearance. However, it is superior to serum determinations of creatinine and beta2M. The intraindividual variation of cystatin C is greater than that of creatinine. This might be due to the better ability of cystatin C to reflect temporary changes especially in mildly impaired GFR, most critical for early detection of rejection and other function impairment. Thus, cystatin C allows for rapid and accurate assessment of renal function (GFR) in renal transplants and is clearly superior to the commonly used serum creatinine.

Heparin-induced thrombocytopenia-associated thrombosis in pediatric intensive care patients

BACKGROUND

Heparin-induced thrombocytopenia (HIT), a well-known side effect of heparin therapy, occurs in 1% to 5% of adults exposed to heparin. Of those, about 29% to 88% develop thrombosis. Most data on HIT-associated thrombosis in children are confined to anecdotal reports.

OBJECTIVE

To determine the incidence of HIT-associated thrombosis in heparin-exposed children.

METHODS

We performed a retrospective cohort study on all patients admitted to our pediatric intensive care unit between August 1996 and January 1999. Patients who received heparin for >/=5 days were eligible. Within these patients, we identified all cases of radiologically confirmed thrombosis. Cases of thrombosis were reviewed for fulfillment of clinical HIT criteria. HIT-associated thrombosis was confirmed serologically by determination of levels of antibodies against heparin/platelet factor 4 complexes.

RESULTS

Of 1950 children admitted during the study period, 612 were exposed to heparin for >/=5 days. Thrombosis occurred in 57 patients (9.3%). Plasma samples were available for 38 cases, of which 14 satisfied clinical HIT-criteria. Calculated incidence rate for HIT-associated thrombosis: 2.3%, (95% confidence interval: 1.3%-3.9%, for patients exposed to heparin >/=5 days). Nine patients suffered from venous, 2 patients from arterial, and 3 had combined arterial and venous thrombosis. None of the 14 patients died or underwent amputation. Six patients had heparin and platelet factor 4-complex antibody levels above the cutoff level for adults. The remaining 8 patients had significantly higher antibody levels than a matched control group.

CONCLUSION

Compared with that reported for adults, HIT-associated thrombosis in pediatric intensive care unit patients has a similar incidence but a less severe outcome.

Age-specific differences between conventional and ambulatory daytime blood pressure values

Mean daytime ambulatory blood pressure (BP) values are considered to be lower than conventional BP values, but data on this relation among younger individuals <50 years are scarce. Conventional and 24-hour ambulatory BP were measured in 9550 individuals not taking antihypertensive treatment from 13 population-based cohorts. We compared individual differences between daytime ambulatory and conventional BP according to 10-year age categories. Age-specific prevalences of white coat and masked hypertension were calculated. Among individuals aged 18 to 30, 30 to 40, and 40 to 50 years, mean daytime BP was significantly higher than the corresponding conventional BP (6.0, 5.2, and 4.7 mm Hg for systolic; 2.5, 2.7, and 1.7 mm Hg for diastolic BP; all P<0.0001). In individuals aged 60 to 70 and ≥70 years, conventional BP was significantly higher than daytime ambulatory BP (5.0 and 13.0 mm Hg for systolic; 2.0 and 4.2 mm Hg for diastolic BP; all P<0.0001).The prevalence of white coat hypertension exponentially increased from 2.2% to 19.5% from those aged 18 to 30 years to those aged ≥70 years, with little variation between men and women (8.0% versus 6.1%; P=0.0003). Masked hypertension was more prevalent among men (21.1% versus 11.4%; P<0.0001). The age-specific prevalences of masked hypertension were 18.2%, 27.3%, 27.8%, 20.1%, 13.6%, and 10.2% among men and 9.0%, 9.9%, 12.2%, 11.9%, 14.7%, and 12.1% among women. In conclusion, this large collaborative analysis showed that the relation between daytime ambulatory and conventional BP strongly varies by age. These findings may have implications for diagnosing hypertension and its subtypes in clinical practice.

Severe COVID-19 is associated with elevated serum IgA and antiphospholipid IgA-antibodies

Background

Severe coronavirus disease 2019 (COVID-19) frequently entails complications that bear similarities to autoimmune diseases. To date, there is little data on possible IgA-mediated autoimmune responses. Here, we aim to determine whether COVID-19 is associated with a vigorous total IgA response and if IgA antibodies are associated with complications of severe illness. Since thrombotic events are frequent in severe COVID-19 and resemble hypercoagulation of antiphospholipid syndrome (APS), our approach focused on antiphospholipid antibodies (aPL).

Methods

In this retrospective cohort study clinical data and aPL from 64 patients with COVID-19 were compared from three independent tertiary hospitals (one in Liechtenstein, two in Switzerland). Samples were collected from April 9 ^th to May 1 ^st, 2020.

Results

Clinical records of 64 patients with COVID-19 were reviewed and divided into a cohort with mild illness (mCOVID) (41%), a discovery cohort with severe illness (sdCOVID) (22%) and a confirmation cohort with severe illness (scCOVID) (38%). Total IgA, IgG and aPL were measured with clinical diagnostic kits. Severe illness was significantly associated with increased total IgA (sdCOVID, P=0.01; scCOVID, p-value<0.001), but not total IgG. Among aPL, both cohorts with severe illness significantly correlated with elevated anti-Cardiolipin IgA (sdCOVID and scCOVID, p-value<0.001), anti-Cardiolipin IgM (sdCOVID, P=0.003; scCOVID, P<0.001), and anti-Beta2 Glycoprotein-1 IgA (sdCOVID and scCOVID, P<0.001). Systemic lupus erythematosus was excluded from all patients as a potential confounder.

Conclusions

Higher total IgA and IgA-aPL were consistently associated with severe illness. These novel data strongly suggest that a vigorous antiviral IgA-response, possibly triggered in the bronchial mucosa, induces systemic autoimmunity.

New alcohol-related genes suggest shared genetic mechanisms with neuropsychiatric disorders

Excessive alcohol consumption is one of the main causes of death and disability worldwide. Alcohol consumption is a heritable complex trait. Here we conducted a meta-analysis of genome-wide association studies of alcohol consumption (g d-1) from the UK Biobank, the Alcohol Genome-Wide Consortium and the Cohorts for Heart and Aging Research in Genomic Epidemiology Plus consortia, collecting data from 480,842 people of European descent to decipher the genetic architecture of alcohol intake. We identified 46 new common loci and investigated their potential functional importance using magnetic resonance imaging data and gene expression studies. We identify genetic pathways associated with alcohol consumption and suggest genetic mechanisms that are shared with neuropsychiatric disorders such as schizophrenia.

Stability of hematological analytes depends on the hematology analyser used: a stability study with Bayer Advia 120, Beckman Coulter LH 750 and Sysmex XE 2100

AIM

With the availability of newer hematology analysers, novel measurement techniques are being introduced into daily routine. As analyte stability may differ according to the employed measurement technique, the aim of this study was to assess the stability of hematologic analytes on different hematology analysers.

METHODS

We investigated the effect of storage time and storage temperature on sample stability on three newer analytical systems (Advia 120, Bayer Diagnostics; XE 2100, Sysmex and LH 750, Beckman Coulter). Samples were obtained from 64 healthy volunteers and stored at room temperature as well at 4-8 degrees C in order to conduct analysis at different timepoints up to 72 h after blood was drawn. Sample stability was assessed by the graphical truncated normal sequential test. A parameter was considered stable, when its average change was smaller than one coefficient of variation CV (%) of the assessed method, allowing a 5% risk of error.

RESULTS

Red blood cell counts, mean corpuscular hemoglobin (MCH) and hemoglobin are least affected by storage temperature and showed stability for at least 48 h, depending on analyser utilized. While reticulocytes, mean corpuscular volume (MCV), hematocrit and leukocyte counts were more stable at 4-8 degrees C, thrombocytes exhibited a better stability at RT. The white blood cell (WBC) subpopulations changed over time with a decrease in eosinophils and lymphocytes and an increase in neutrophils at 4-8 degrees C. Further, the stability pattern of WBC subpopulations was significantly different among the 3 investigated analysers with some analytes only displaying a stability of 4 h.

CONCLUSIONS

Analyte stability of hematological parameters varies not only according to the investigated parameter but also according to storage temperature and the employed measurement system. Depending on the analyte sample stability differences among the different analytical systems are considerable.

Multi-ancestry GWAS of the electrocardiographic PR interval identifies 202 loci underlying cardiac conduction

The electrocardiographic PR interval reflects atrioventricular conduction, and is associated with conduction abnormalities, pacemaker implantation, atrial fibrillation (AF), and cardiovascular mortality. Here we report a multi-ancestry (N = 293,051) genome-wide association meta-analysis for the PR interval, discovering 202 loci of which 141 have not previously been reported. Variants at identified loci increase the percentage of heritability explained, from 33.5% to 62.6%. We observe enrichment for cardiac muscle developmental/contractile and cytoskeletal genes, highlighting key regulation processes for atrioventricular conduction. Additionally, 8 loci not previously reported harbor genes underlying inherited arrhythmic syndromes and/or cardiomyopathies suggesting a role for these genes in cardiovascular pathology in the general population. We show that polygenic predisposition to PR interval duration is an endophenotype for cardiovascular disease, including distal conduction disease, AF, and atrioventricular pre-excitation. These findings advance our understanding of the polygenic basis of cardiac conduction, and the genetic relationship between PR interval duration and cardiovascular disease.

Metabolic and anti-inflammatory benefits of eccentric endurance exercise - a pilot study

BACKGROUND

Eccentric endurance exercise (e.g. hiking downwards) is less strenuous than concentric exercise (e.g. hiking upwards) but its potential to reduce cardiovascular risk is unknown.

MATERIALS AND METHODS

We randomly allocated 45 healthy sedentary individuals (16 men and 29 women, mean age 48 years) to one of two groups, one beginning with two months of hiking upwards, the other with two months of hiking downwards the same route, with a crossover for a further two months. For the opposite way, a cable car was used where compliance was recorded electronically. The difference in altitude was 540 metres; the distance was covered three to five times a week. Fasting and postprandial metabolic profiles were obtained at baseline and after the two month periods of eccentric and concentric exercise, respectively.

RESULTS

Forty-two of the 45 participants completed the study; the compliance rate was therefore 93%. Compared with baseline, eccentric exercise lowered total cholesterol (by 4.1%; P = 0.026), low-density lipoprotein (LDL) cholesterol (by 8.4%, P = 0.001), Apolipoprotein B/Apolipoprotein A1 ratio (by 10.9%, P < 0.001), homeostasis model assessment of insulin resistance scores (by 26.2%, P = 0.017) and C-reactive protein (by 30.0%; P = 0.007); the magnitude of these changes was comparable to that of concentric exercise. Eccentric exercise improved glucose tolerance (by 6.2%, P = 0.023), whereas concentric exercise improved triglyceride tolerance (by 14.9%, P = 0.022).

CONCLUSIONS

Eccentric endurance exercise is a promising new exercise modality with favourable metabolic and anti-inflammatory effects and is well applicable to sedentary individuals.

The cystatin C/creatinine ratio, a marker of glomerular filtration quality: associated factors, reference intervals, and prediction of morbidity and mortality in healthy seniors

The ratio of cystatin C (cysC) to creatinine (crea) is regarded as a marker of glomerular filtration quality associated with cardiovascular morbidities. We sought to determine reference intervals for serum cysC-crea ratio in seniors. Furthermore, we sought to determine whether other low-molecular weight molecules exhibit a similar behavior in individuals with altered glomerular filtration quality. Finally, we investigated associations with adverse outcomes. A total of 1382 subjectively healthy Swiss volunteers aged 60 years or older were enrolled in the study. Reference intervals were calculated according to Clinical & Laboratory Standards Institute (CLSI) guideline EP28-A3c. After a baseline exam, a 4-year follow-up survey recorded information about overall morbidity and mortality. The cysC-crea ratio (mean 0.0124 ± 0.0026 mg/μmol) was significantly higher in women and increased progressively with age. Other associated factors were hemoglobin A1c, mean arterial pressure, and C-reactive protein (P < 0.05 for all). Participants exhibiting shrunken pore syndrome had significantly higher ratios of 3.5-66.5 kDa molecules (brain natriuretic peptide, parathyroid hormone, β2-microglobulin, cystatin C, retinol-binding protein, thyroid-stimulating hormone, α1-acid glycoprotein, lipase, amylase, prealbumin, and albumin) and creatinine. There was no such difference in the ratios of very low-molecular weight molecules (urea, uric acid) to creatinine or in the ratios of molecules larger than 66.5 kDa (transferrin, haptoglobin) to creatinine. The cysC-crea ratio was significantly predictive of mortality and subjective overall morbidity at follow-up in logistic regression models adjusting for several factors. The cysC-crea ratio exhibits age- and sex-specific reference intervals in seniors. In conclusion, the cysC-crea ratio may indicate the relative retention of biologically active low-molecular weight compounds and can independently predict the risk for overall mortality and morbidity in the elderly.

Risk factors for premature ventricular contractions in young and healthy adults

BACKGROUND

Premature ventricular contractions (PVCs) are associated with an increased risk of morbidity and mortality. Therefore, it was aimed to assess risk factors for the frequency of PVCs in young and healthy adults.

METHODS

Our population-based study included 2048 healthy adults from the general population aged 25-41 years. PVC frequency was determined by 24-hour Holter ECG. We performed multivariable regression analysis using stepwise backward selection to identify factors independently associated with PVC frequency.

RESULTS

Median age was 37 years, 953 (46.5%) were male. At least one PVC during the 24-hour monitoring period was observed in 69% of participants. Median number of detected PVCs was 2, the 95th percentile was 193. In multivariable regression analyses, we found 17 significant risk factors for PVC frequency. Low educational status (risk ratio (RR) 3.33; 95% CI 1.98 to 5.60), body height>median (1.58, 95% CI 1.11 to 2.24) and increasing levels of waist:hip ratio (2.15, 95% CI 1.77 to 2.61), N-terminal pro brain natriuretic peptide (1.52, 95% CI 1.30 to 1.76) and Sokolow-Lyon Index (1.38, 95% CI 1.15 to 1.66) (all p≤0.01) were associated with a higher PVC frequency. Physical activity (RR fourth vs first quartile 0.51, 95% CI 0.34 to 0.76) and increasing levels of haemoglobin (0.58, 95% CI 0.47 to 0.70) and glucagon-like peptide-1 (0.72, 95% CI 0.64 to 0.82) (all p<0.001) were related to a lower PVC frequency.

CONCLUSIONS

PVC occurrence is common even in healthy low-risk individuals, and its frequency is associated with several covariates mainly related to cardiovascular risk factors, markers of cardiac structure and function and socioeconomic status.

Antibodies as biomarker candidates for response and survival to checkpoint inhibitors in melanoma patients

Background

Long-term survival of stage IV melanoma patients has improved significantly with the development of immune checkpoint inhibitors (CIs). Reliable biomarkers to predict response and clinical outcome are needed.

Methods

We investigated the role of melanoma-associated antibodies as predictive markers for CI therapy in two independent cohorts. In cohort 1, a prospective study, we measured specific antibodies before treatment, after one week and after six to nine weeks of treatment. Cohort 2 consisted of serum samples prior to CI therapy initiation. ELISA assays were performed to quantify specific IgG directed against melanocyte differentiation antigens tyrosinase-related proteins 1 and 2 (TRP1/TYRP1 and TRP2/TYRP2), glycoprotein 100 (gp100), MelanA/MART1, and the cancer-testis antigen NY-ESO-1. Response was defined as either complete or partial remission on CT scan according to RECIST 1.1.

Results

In cohort 1, baseline levels of these antibodies were higher in the responder group, although statistical significance was only reached for NY-ESO-1 (p = 0.007). In cohort 2, significantly higher antibody baseline levels for MelanA/MART1 (p = 0.003) and gp100 (p = 0.029) were found. After pooling the results from both cohorts, higher levels of MelanA/MART1 (p = 0.013), TRP1/TYRP1 (p = 0.048), TRP2/TYRP2 (p = 0.047) and NY-ESO-1 (p = 0.005) specific antibodies at baseline were independently associated with response.

Conclusions

Melanoma-associated antibodies may be candidate biomarkers for response and survival in metastatic melanoma patients being treated with CIs. These markers may be used to complement patient assessment, in combination with PD-L1 status, tumor-infiltrating lymphocytes and tumor mutational burden, with the aim to predict outcome of CI treatment in patients with metastatic melanoma.

Trial registration

Ethikkommission Ostschweiz, EKOS 16/079 https://ongoingprojects.swissethics.ch/runningProjects_list.php?q=%28BASECID~contains~2016-00998%29&orderby=dBASECID.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0523-2) contains supplementary material, which is available to authorized users.

Heparin-induced thrombocytopenia in paediatrics: clinical characteristics, therapy and outcomes

OBJECTIVE

Reports on heparin-induced thrombocytopenia (HIT) in paediatrics are confined to isolated case reports. The objective was to systematically combine the published data.

DESIGN AND SETTING

Cases were identified by MEDLINE search and review of bibliographies.

PATIENTS

We included subjects reported with HIT, collecting patient demographics, clinical and laboratory characteristics, therapeutic regimens and outcomes.

MEASUREMENTS AND RESULTS

Reports on 70 patients were retrieved. In a majority of children, HIT occurred during hospitalisation in a paediatric ICU. In most patients, the typical onset pattern was reported, although rapid-onset-pattern HIT occurred in some. The median platelet-count nadir was 54x10(9)/l; 11% of reported patients had nadirs in the normal range. Clinical symptoms included isolated thrombocytopenia and solitary or combined venous, arterial and intracardiac thromboembolism, sometimes catheter-related. Pulmonary embolism and major bleeding were rarely described. Confirmatory functional or antigenic testing of HIT antibodies showed a similar cumulative sensitivity of about 88%. An unfavourable outcome (death/limb amputation) was reported in 42.1% of patients without therapy and in 18% of patients treated with danaparoid, lepirudin, or argatroban.

CONCLUSIONS

HIT in children mainly occurs in paediatric intensive care with diagnostic features and outcomes similar to those seen in adults. HIT cannot be ruled out based on normal platelet counts or occurrence after fewer than 5 days of heparin exposure. Children should be presumed to suffer from HIT based on clinical grounds and treated accordingly (immediate heparin withdrawal and alternative anticoagulation). Alternative anticoagulation with danaparoid, lepirudin and argatroban appears to improve outcomes.

The complexity of kidney disease and diagnosing it - cystatin C, selective glomerular hypofiltration syndromes and proteome regulation

Estimation of kidney function is often part of daily clinical practice, mostly done by using the endogenous glomerular filtration rate (GFR)-markers creatinine or cystatin C. A recommendation to use both markers in parallel in 2010 has resulted in new knowledge concerning the pathophysiology of kidney disorders by the identification of a new set of kidney disorders, selective glomerular hypofiltration syndromes. These syndromes, connected to strong increases in mortality and morbidity, are characterized by a selective reduction in the glomerular filtration of 5-30 kDa molecules, such as cystatin C, compared to the filtration of small molecules <1 kDa dominating the glomerular filtrate, for example water, urea and creatinine. At least two types of such disorders, shrunken or elongated pore syndrome, are possible according to the pore model for glomerular filtration. Selective glomerular hypofiltration syndromes are prevalent in investigated populations, and patients with these syndromes often display normal measured GFR or creatinine-based GFR-estimates. The syndromes are characterized by proteomic changes promoting the development of atherosclerosis, indicating antibodies and specific receptor-blocking substances as possible new treatment modalities. Presently, the KDIGO guidelines for diagnosing kidney disorders do not recommend cystatin C as a general marker of kidney function and will therefore not allow the identification of a considerable number of patients with selective glomerular hypofiltration syndromes. Furthermore, as cystatin C is uninfluenced by muscle mass, diet or variations in tubular secretion and cystatin C-based GFR-estimation equations do not require controversial race or sex terms, it is obvious that cystatin C should be a part of future KDIGO guidelines.

Rapid, accurate and non-invasive detection of cerebrospinal fluid leakage using combined determination of β-trace protein in secretion and serum

BACKGROUND

beta-Trace protein (Btp) has been proposed as a valuable marker of cerebrospinal fluid (CSF) leakage overcoming the drawbacks of beta-2-transferrin (B-2Tr) determination. However, there is still controversy about the appropriate cut-offs to be used (range 0.35-6 mg/L). The aim of the study was to evaluate cut-offs of Btp determination for detection CSF leakage. Further, we assessed whether the Btp secretion to serum ratio (Btp-sec/ser-ratio) would add diagnostic value.

METHODS

Prospective study in patients with suspected CSF leakage. Quantitative determination of Btp in secretion and serum (Dade-Behring) and qualitative measurement of B-2-Tr in secretion and serum. Results were assessed in view of clinical data. Cut-offs and diagnostic characteristics were determined by ROC analysis.

RESULTS

A total of 176 samples were assessed originating from 105 patients. In 43 samples CSF leakage could be confirmed. Sensitivity of B-2-Tr was 84%, specificity amounted to 100%. The area under the curve (AUC) for Btp-measurement in secretion was 0.98. At a cut-off of 0.68 mg/L, sensitivity was 100% and specificity 91%. At a cut-off of 1.11 mg/L, the specificity was 100% with a sensitivity of 93%. The Btp-sec/ser-ratio has an AUC of 0.99. Combining a 0.68 mg/L cut-off in secretion with a Btp-sec/ser-ratio cut-off of 4.9 reveals a sensitivity of 99% and a specificity of 100%.

CONCLUSIONS

Btp is a rapid and accurate marker for the presence of CSF leakage. Combining measurement of Btp in secretion together with determination of the Btp-sec/ser-ratio enhances the diagnostic characteristics of the Btp assay. Determination of Btp in both serum and secretion is thus recommended.

Assessment of renal function in renal transplant patients using cystatin C. A comparison to other renal function markers and estimates

To date, little evidence is available to define the role of cystatin C in patients with renal transplants. Thus, to assess, whether cystatin C (CysC) provides better information on renal function than other markers, CysC, creatinine clearance (CrCl), serum creatinine (SCr), beta2-microglobulin (beta2-M), and 125I-Iothalamate clearance were determined in 30 patients. Correlation and ROC curves were obtained and characteristics like sensitivity and specificity were calculated. Further, to evaluate the usefulness of these markers for monitoring, intraindividual coefficients of variation for CysC and SCr measurements were compared in 85 renal transplant patients. CysC correlated best with GFR, whereas SCr, CrCl and beta2-M all had lower correlation coefficients. CysC was superior to SCr, even when renal function equations of were used. The diagnostic accuracy of CysC was significantly better than SCr. but did not differ significantly from CrCl and beta2-M. Together, our data show that in patients with renal transplants, CysC has a similar diagnostic value as CrCl. However, it is superior to determinations of SCr. The intraindividual variation of CysC is significantly greater than that of SCr. This might be due to better ability of CysC to reflect temporary changes especially in mildly impaired GFR, most critical for early detection of rejection and other function impairment. In conclusion, CysC allows for easy and accurate assessment of renal function (GFR) in steady state renal transplant patients and is clearly superior to the commonly used serum creatinine.

Anemia in tuberculosis cases and household controls from Tanzania: Contribution of disease, coinfections, and the role of hepcidin

Background

Tuberculosis (TB) induces a systemic inflammatory state affecting iron homeostasis. Patients with TB often have additional comorbidities such as anemia which can result in poorer treat outcomes. We studied the contribution of anemia and the role of the iron regulatory hormone hepcidin among TB patients and household contacts.

Methods

We analyzed serum samples from 102 TB cases and 98 controls without TB, matched by age/sex, for hepcidin, iron, and inflammation parameters. Five controls developed TB within 12 months. We used linear regression to assess associations.

Results

Anemia of chronic disease (ACD) was more frequent among cases than controls (59.8% vs. 26.1%), but iron-deficiency anemia more frequent in controls (10% vs. 1%). The median hepcidin level was higher in cases than controls (63.7 vs. 14.2 ng/mL), but coinfections with HIV, helminths, and respiratory pathogens did not show cumulative effects. Hepcidin was associated with more severe TB symptom scoring (coefficient 0.8, 95% confidence interval [CI] 0.5–1.2) and higher mycobacterial load (0.7, 95% CI 0.4–1.0). Hepcidin was higher in TB cases and controls who developed TB compared to controls without TB (p<0.001), even when restricting to HIV-negative study participants.

Conclusions

ACD was the predominate etiology in TB patients suggesting limited benefit from iron supplementation. Increased hepcidin levels long before active disease, indicating altered iron metabolism, may be a marker for developing disease among TB-exposed individuals. Clinical management of anemia and nutrition interventions in TB patients need to be considered to improve the clinical course and outcomes.

Frequency of serological non-responders and false-negative RT-PCR results in SARS-CoV-2 testing: a population-based study

Objectives The sensitivity of molecular and serological methods for COVID-19 testing in an epidemiological setting is not well described. The aim of the study was to determine the frequency of negative RT-PCR results at first clinical presentation as well as negative serological results after a follow-up of at least 3 weeks. Methods Among all patients seen for suspected COVID-19 in Liechtenstein (n=1921), we included initially RT-PCR positive index patients (n=85) as well as initially RT-PCR negative (n=66) for follow-up with SARS-CoV-2 antibody testing. Antibodies were detected with seven different commercially available immunoassays. Frequencies of negative RT-PCR and serology results in individuals with COVID-19 were determined and compared to those observed in a validation cohort of Swiss patients (n=211). Results Among COVID-19 patients in Liechtenstein, false-negative RT-PCR at initial presentation was seen in 18% (12/66), whereas negative serology in COVID-19 patients was 4% (3/85). The validation cohort showed similar frequencies: 2/66 (3%) for negative serology, and 16/155 (10%) for false negative RT-PCR. COVID-19 patients with negative follow-up serology tended to have a longer disease duration (p=0.05) and more clinical symptoms than other patients with COVID-19 (p<0.05). The antibody titer from quantitative immunoassays was positively associated with the number of disease symptoms and disease duration (p<0.001). Conclusions RT-PCR at initial presentation in patients with suspected COVID-19 can miss infected patients. Antibody titers of SARS-CoV-2 assays are linked to the number of disease symptoms and the duration of disease. One in 25 patients with RT-PCR-positive COVID-19 does not develop antibodies detectable with frequently employed and commercially available immunoassays.

Assessing glomerular filtration rate in renal transplant recipients by estimates derived from serum measurements of creatinine and cystatin C

BACKGROUND

Assessing glomerular filtration rate (GFR) is of importance in the surveillance of renal transplant recipients. As serum markers alone are inaccurate for estimating GFR, several equations have been developed with the aim of translating a serum value into a corresponding and more accurate GFR. The present study investigated the diagnostic characteristics of GFR estimates obtained by the simplified MDRD formula and the cystatin C based estimate described by Larsson et al.

METHODS

Prospective study in 29 stable renal transplant recipients. GFR was assessed with (125)I-Iothalamate clearance, creatinine was measured with a modified Jaffe method on Dimension RxL (Dade-Behring, Dudingen, Switzerland), cystatin C was determined by particle enhanced turbidimetric immunassay (PETIA; Dako, Glostrup, Denmark). Bias, precision and diagnostic accuracy of the two GFR estimates were assessed with Bland-Altman method and receiver-operating characteristics (ROC) analysis. The latter was performed at a GFR cut-off of 60 ml/min/1.73 m2.

RESULTS

The cystatin C based GFR estimate normalized to a body surface area of 1.73 m2 exhibited a bias of -4.7 ml/min/1.73 m2, the 95% limits of agreement were -25.5-16 ml/min/1.73 m2 with an AUC of 0.87. The MDRD estimates obtained from the original creatinine revealed biased results. Thus, non-constant recalibration of creatinine was done. Recalibrated creatinine gave an MDRD GFR estimate with a bias of 1.7 ml/min/1.73 m2. The limits of agreement were -23.1-26.4 ml/min/1.73 m2. ROC analysis revealed an AUC 0.8 and was not significantly different from the cystatin C based GFR estimate.

CONCLUSIONS

In renal transplant recipients, the cystatin C based GFR estimate exhibits similar diagnostic characteristics like the simplified MDRD formula. In contrast to cystatin C measurement, recalibration of creatinine might be necessary before implementing the simplified MDRD formula into clinical routine.

Post-Acute Sequelae After Severe Acute Respiratory Syndrome Coronavirus 2 Infection by Viral Variant and Vaccination Status: A Multicenter Cross-Sectional Study

BACKGROUND

Disentangling the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and vaccination on the occurrence of post-acute sequelae of SARS-CoV-2 (PASC) is crucial to estimate and reduce the burden of PASC.

METHODS

We performed a cross-sectional analysis (May/June 2022) within a prospective multicenter healthcare worker (HCW) cohort in north-eastern Switzerland. HCWs were stratified by viral variant and vaccination status at time of their first positive SARS-CoV-2 nasopharyngeal swab. HCWs without positive swab and with negative serology served as controls. The sum of 18 self-reported PASC symptoms was modeled with univariable and multivariable negative-binomial regression to analyze the association of mean symptom number with viral variant and vaccination status.

RESULTS

Among 2912 participants (median age: 44 years; 81.3% female), PASC symptoms were significantly more frequent after wild-type infection (estimated mean symptom number: 1.12; P < .001; median time since infection: 18.3 months), after Alpha/Delta infection (0.67 symptoms; P < .001; 6.5 months), and after Omicron BA.1 infections (0.52 symptoms; P = .005; 3.1 months) versus uninfected controls (0.39 symptoms). After Omicron BA.1 infection, the estimated mean symptom number was 0.36 for unvaccinated individuals versus 0.71 with 1-2 vaccinations (P = .028) and 0.49 with ≥3 prior vaccinations (P = .30). Adjusting for confounders, only wild-type (adjusted rate ratio [aRR]: 2.81; 95% confidence interval [CI]: 2.08-3.83) and Alpha/Delta infections (aRR: 1.93; 95% CI: 1.10-3.46) were significantly associated with the outcome.

CONCLUSIONS

Previous infection with pre-Omicron variants was the strongest risk factor for PASC symptoms among our HCWs. Vaccination before Omicron BA.1 infection was not associated with a clear protective effect against PASC symptoms in this population.

Vitamin B12 and folate levels in healthy Swiss senior citizens: a prospective study evaluating reference intervals and decision limits

BACKGROUND

The vitamin B12 and folate status in nonanaemic healthy older persons needs attention the more so as decrease in levels may be anticipated from reduced haematinic provision and/or impaired intestinal uptake.

METHODS

A total of 1143 subjectively healthy Swiss midlands participants (637 females and 506 males), ≥60 years of age were included in this study. Levels of vitamin B12, holotranscobalamin (holoTC), methylmalonic acid (MMA), homocysteine (Hcy), serum folate, red blood cell (RBC) folate were measured. Further, Fedosov's wellness score was determined. Associations of age, gender, and cystatin C/creatinine-based estimated kidney function, with the investigated parameters were assessed. Reference intervals were calculated. Further, ROC analysis was done to assess accuracy of the individual parameters in recognizing a deficient vitamin B12 status. Finally, decision limits for sensitive, specific and optimal recognition of vitamin B12 status with individual parameters were derived.

RESULTS

Three age groups: 60-69, 70-79 and ≥ 80 had median B12 (pmol/L) levels of 237, 228 and 231 respectively (p = 0.22), holoTC (pmol/L) of 52, 546 and 52 (p = 0.60) but Hcy (μmol/L) 12, 15 and 16 (p < 0.001), MMA (nmol/L) 207, 221 and 244 (p < 0.001). Hcy and MMA (both p < 0.001), but not holoTC (p = 0.12) and vitamin B12 (p = 0.44) were found to be affected by kidney function. In a linear regression model Fedosov's wellness score was independently associated with kidney function (p < 0.001) but not with age. Total serum folate and red blood cell (RBC) folate drift apart with increasing age: whereas the former decreases (p = 0.01) RBC folate remains in the same bandwidth across all age groups (p = 0.12) A common reference interval combining age and gender strata can be obtained for vitamin B12 and holoTC, whereas a more differentiated approach seems warranted for serum folate and RBC folate.

CONCLUSION

Whereas the vitamin B12 and holoTC levels remain steady after 60 years of age, we observed a significant increment in MMA levels accompanied by increments in Hcy; this is better explained by age-related reduced kidney function than by vitamin B12 insufficiency. Total serum folate levels but not RBC folate levels decreased with progressing age.