Background Trimethylamine N-oxide (TMAO), a metabolite from red meat and fish consumption, plays a role in promoting cardiovascular events. However, data regarding TMAO and its impact on clinical outcomes are inconclusive, possibly due to its undetermined dietary source. Objective We hypothesized circulating TMAO derived from fish intake might cause less harm compared to red meat source by examining the concomitant level of 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), a known biomarker of fish intake, and investigated the association between TMAO, CMPF and outcomes. Design Patients were recruited from the European QUALity study on treatment in advanced CKD (EQUAL) among individuals ≥65 years whose eGFR had dropped for the first time to ≤20mL/min/1.73m2 during last 6 months. The association between TMAO, CMPF and outcomes including all-cause mortality and kidney replacement therapy (KRT) was assessed among 737 patients. Patients were further stratified by median cut-offs of TMAO and CMPF, suggesting high/low red meat and fish intake. Results During a median of 39 months’ follow-up, 232 patients died. Higher TMAO was independently associated with an increased risk of all-cause mortality (multivariable-hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.17, 1.83). Higher CMPF was associated with a reduced risk of both all-cause mortality (HR 0.79, 95%CI 0.71, 0.89) and KRT (HR 0.80, 95%CI 0.71, 0.90), independent of TMAO and other clinically relevant confounders. In comparison to patients with low TMAO and CMPF, patients with low TMAO and high CMPF had reduced risk of all-cause mortality (adjusted HR 0.49, 95% CI 0.31, 0.73), whereas those with high TMAO and high CMPF showed no association across adjusted models. Conclusions High CMPF conferred an independent role in health benefits and might even counteract the unfavorable association between TMAO and outcomes. Whether higher circulating CMPF are due to fish consumption, and/or CMPF is a protective factor remains to be verified.

Background Patients with stage 4/5 chronic kidney disease (CKD) suffer from various symptoms. The retention of uremic solutes is thought to be associated with those symptoms. However, there are relatively few rigorous studies on the potential links between uremic toxins and symptoms in patients with CKD. Methods The EQUAL study is an ongoing observational cohort study of non-dialyzed patients with stage 4/5 CKD. EQUAL patients from Germany, Poland, Sweden, and the United Kingdom were included in the present study (n = 795). Data and symptoms self-report questionnaires were collected between April 2012 and September 2020. Baseline uric acid and parathyroid hormone and ten uremic toxins were quantified. We tested the association between uremic toxins and symptoms, and adjusted p-values for multiple testing. Results Symptoms were more frequent in women than in men with stage 4/5 CKD, while levels of various uremic toxins were higher in men. Only trimethylamine-N-oxide (positive association with fatigue), p-cresylsulfate with constipation, and 3 carboxy-4-methyl-5-propyl-2-furanpropionic acid (negative association with shortness of breath) demonstrated moderately strong associations with symptoms in adjusted analysis. The association of phenylacetylglutamine with shortness of breath was consistent in both sexes, although only reached statistical significance in the full population. By contrast, trimethylamine-N-oxide (fatigue) and p-cresyl sulfate and phenylacetylglutamine (constipation) were only associated with symptoms in men, who presented higher serum levels than women. Conclusion Only a limited number of toxins were associated with symptoms in persons with stage 4/5 CKD. Other uremic toxins, uremia related factors or psychosocial factors not yet explored might contribute to symptom burden.

Background Patients with chronic kidney disease (CKD) are at a higher risk of major adverse cardiovascular events (MACE) compared to the general population, but gender differences in this risk, especially in older adults, are not fully known. We aim to identify gender differences in the risk of MACE in older European CKD patients, and explore factors which may explain these differences. Methods The European Quality study (EQUAL) is a prospective study on stage 4–5 CKD patients, ≥65 years old, not on dialysis, from Germany, Italy, the Netherlands, Poland, Sweden, and the UK. Cox regression and cumulative incidence competing risk curves were used to identify gender differences in MACE risks. Mediation analysis was used to identify variables which may explain risk differences between men and women. Results 417 men out of 1 134 (37%) and 185 women out of 602 women (31%) experienced at least one MACE, over a follow-up period of 5 years. Women had an 18% lower risk of first MACE compared to men (HR: 0.82; 95% CI: 0.69–0.97; p = 0.02), which was attenuated after adjusting for pre-existing cardiometabolic comorbidities and cardiovascular risk factors. There were no significant gender differences in the risk of recurrent MACE or fatal MACE. The risk difference in MACE by gender was larger in patients aged 65–75, compared to patients over 75. Conclusions In a cohort of older adults with advanced CKD, women had lower risks of MACE. These risk differences were partially explained by pre-existing cardiometabolic comorbidities and cardiovascular risk factors.

Background We explore longitudinal trajectories of clinical indicators, patient-reported outcomes, and hospitalizations, in the years preceding death, in a population of older patients with advanced CKD. Methods The EQUAL study is a European observational prospective cohort study with an incident eGFR<20 ml/min per 1.73 m2 and ≥ 65 years of age. The evolution of each clinical indicator was explored using generalized additive models during the 4 years preceding death. Results We included 661 decedents with a median time-to-death of 2.0 years (IQR 0.9–3.2). During the years preceding death, eGFR, subjective global assessment score, and blood pressure declined, with accelerations seen at 6 months preceding death. Serum hemoglobin, hematocrit, cholesterol, calcium, albumin, and sodium values declined slowly during follow-up, with accelerations observed between 6 and 12 months preceding death. Physical and mental quality of life declined linearly throughout follow-up. The number of reported symptoms was stable up to 2 years prior to death, with an acceleration observed at 1 year prior to death. The rate of hospitalization was stable at around 1 hospitalization per person year, increasing exponentially at 6 months preceding death. Conclusions We identified clinically relevant physiological accelerations in patient trajectories that began approximately 6 to 12 months prior to death, which are likely multifactorial in nature, but correlate with a surge in hospitalizations. Further research should focus on how to effectively use this knowledge to inform patient and family expectations, to benefit the planning of (end-of-life) care, and to establish clinical alert systems.

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