Emerging evidence suggests that diet, particularly one that is rich in dietary fiber, may prevent the progression of chronic kidney disease (CKD) and its associated complications in people with established CKD. This narrative review summarizes the current evidence and discusses the opportunities for increasing fiber intake in people with CKD to improve health and reduce disease complications. A higher consumption of fiber exerts multiple health benefits, such as increasing stool output, promoting the growth of beneficial microbiota, improving the gut barrier and decreasing inflammation, as well decreasing uremic toxin production. Despite this, the majority of people with CKD consume less than the recommended dietary fiber intake, which may be due in part to the competing dietary potassium concern. Based on existing evidence, we see benefits from adopting a higher intake of fiber-rich food, and recommend cooperation with the dietitian to ensure an adequate diet plan. We also identify knowledge gaps for future research and suggest means to improve patient adherence to a high-fiber diet.

General and abdominal obesity are prevalent, with established associations to frailty in the elderly. However, few studies have investigated these associations in patients with chronic kidney disease (CKD), yielding inconsistent results. This cross-sectional study analysed data from the National Health and Nutrition Examination Survey (NHANES 2003–2018). Frailty was evaluated by the 36-item frailty index. General obesity was defined as a body mass index (BMI) >30 kg/m²; abdominal obesity was identified if waist circumference (WC) reached 102 cm in men and 88 cm in women. The associations of general and abdominal obesity with frailty were analysed using weighted multivariate logistic regression and restricted cubic splines. The interaction of general and abdominal obesity with frailty was examined. A total of 5604 adult patients (median age 71 years, 42% men) with CKD were included in this analysis, with a median estimated glomerular filtration rate of 57.3 ml/min/1.73 m². A total of 21% were frail with general obesity and 32% were frail with abdominal obesity. Neither general nor abdominal obesity alone was associated with frailty. There was an interaction between general and abdominal obesity with frailty. Compared with individuals with normal BMI and WC, those with both general and abdominal obesity, rather than either alone, exhibited significantly increased odds of frailty {odds ratio [OR] 1.53 [95% confidence interval (CI) 1.20–1.95]}. General obesity was associated with being frail only when CKD patients had abdominal obesity [OR 1.59 (95% CI 1.08–2.36)]. There may be an interaction between general and abdominal obesity with frailty in patients with CKD. Interventions aimed at preventing frailty should consider both aspects.

Estimates of the incidence of acute kidney disease (AKD) and its associated adverse outcomes are inconsistent, which may be due in part to differences in prior studies' definitions of AKD. This study sought to summarize these reports and identify study-level characteristics, including the definition of AKD, that may explain the observed heterogeneity. Systematic review and meta-analysis. Adults aged≥18 years and not receiving maintenance kidney replacement therapy. Observational studies that assessed the incidence of AKD and its association with adverse outcomes. Two reviewers independently extracted data and assessed study quality. AKD definitions were classified as (1) Acute Disease Quality Initiative (ADQI) or ADQI-equivalent or (2) KDIGO (Kidney Disease: Improving Global Outcomes) or KDIGO-equivalent. A random-effects meta-analysis was used to calculate pooled estimates of incidence and the relationship between AKD and outcomes (mortality, kidney failure, onset of chronic kidney disease) summarized by ORs and 95% CIs. Among 1,883 identified studies, 59, involving nearly 6 million participants, met the inclusion criteria. Most studies were classified as being of good quality per the Newcastle-Ottawa scale (n=44). The pooled incidence of AKD was higher when defined by ADQI/ADQI-equivalent criteria compared with KDIGO/KDIGO-equivalent criteria (26.6% [95% CI, 20.3-34.9%] vs 11.1% [95% CI, 7.6-16.3%]; P<0.001). The pooled OR of all-cause mortality associated with AKD was similar whether defined with KDIGO/KDIGO-equivalent or ADQI/ADQI-equivalent criteria (3.8 [95% CI, 2.2-6.7] vs 3.0 [95% CI, 2.1-4.4]; P=0.5). After accounting for baseline acute kidney injury status, the incidence of AKD and its association with all-cause mortality were similar for the 2 definitions. The incidences of AKD were 13.6% and 11.1%, and the ORs for all-cause mortality were not different (4.2 [95% CI, 2.0-8.7] vs 3.8 [95% CI, 2.2-6.7]; P=0.8) using the ADQI/ADQI-equivalent and KDIGO/KDIGO-equivalent definitions, respectively. Similar results were observed for the association between AKD and the development of chronic kidney disease, but the association between AKD and kidney failure was stronger in studies that used the KDIGO/KDIGO-equivalent definition. Heterogeneity persisted across most of the examined subgroups. Estimates for AKD incidence and AKD-associated risk for clinical outcomes vary by the definition used for AKD. These findings inform the assessment of the incidence and consequences of AKD in research and clinical settings. Registered at PROSPERO with identification number CRD42024515828. In this systematic review and meta-analysis of 59 studies involving nearly 6 million participants, we found that acute kidney disease (AKD) is globally prevalent and is associated with higher risks of adverse outcomes, including all-cause mortality, chronic kidney disease, and kidney failure. Estimates of AKD incidence and AKD-associated risks of clinical outcomes vary significantly depending on the definition of AKD used. The selection of the definition for AKD and the presence of baseline acute kidney injury influence the estimate of AKD incidence and its association with health consequences. The findings of this study should guide efforts to refine clinical guidelines and inform public health strategies to address the global burden of AKD more effectively.

Cardiovascular disease (CVD), chronic kidney disease (CKD), diabetes, and obesity frequently coexist and share overlapping pathophysiological mechanisms, contributing to poor health outcomes and high mortality. Recognising this interaction, the cardiovascular-kidney-metabolic (CKM) syndrome has been proposed to advance and unify the concepts of cardiorenal syndrome and metabolic syndrome. CKM syndrome is staged from 0 to 4, reflecting disease progression tracking and risk stratification, and emphasizes life-course screening to detect early metabolic and kidney abnormalities. Early identification of albuminuria and reduced kidney function, even in youth with metabolic risk factors, may slow CKD progression and reduce long-term complications. Further development and validation of risk prediction tools for major cardiovascular and kidney failure events in patients with CKM will help to guide individual therapeutic intervention. For nephrologists, this paradigm offers an opportunity to be involved in the interdisciplinary care model. In the future CKM care model, it would be ideal to have dedicated CKM coordinators in place to enhance collaboration between primary care and all the other specialties involved to improve outcomes, and reduce the global burden of CKM syndrome.

Chronic kidney disease (CKD) is common among older adults, with more than a third of individuals older than 65 years having moderate to severe CKD globally. Management of CKD in older adults is often complex because of multiple comorbidities, polypharmacy, and frailty. However, older adults remain under-represented in clinical trials for both type 2 diabetes (T2D), which is the leading risk factor for CKD, and CKD itself. Recent analyses show consistent low representation of older adults in T2D trials. Similarly, participants of dialysis trials tend to be younger, healthier, and have a lower mortality rate than individuals in the real-world dialysis population, and even greater age disparities are reported in trials for non-dialysis-dependent CKD. This under-representation limits the evidence base for treating older adults and often compels clinicians to extrapolate findings from younger populations or rely on observational data. Consequently, both undertreatment and overtreatment of T2D and CKD might occur. Excluding older adults from trial participation leads to society bearing the costs of avoidable harms from preventable adverse events, inappropriate medication use, and missed opportunities to improve functional outcomes in an ageing population. Addressing this age gap in trial population and target treatment population is crucial to ensure evidence-based, equitable care for older adults. In this Personal View, we explore the barriers of under-representation of older adults and propose strategies to enhance their inclusion in future trials for T2D and CKD.

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