Sarcopenia is a risk factor for adverse clinical outcomes in chronic kidney disease (CKD) patients, including mortality. Diagnosis depends on adopted consensus definition and cutoff values; thus, prevalence rates are generally heterogeneous. We conducted a systematic review and meta‐analysis to investigate the global prevalence of sarcopenia and its traits across the wide spectrum of CKD. A systematic search was conducted using databases, including MEDLINE and EMBASE, for observational studies reporting the prevalence of sarcopenia. We considered sarcopenia according to the consensus definition of the European Working Group on Sarcopenia in Older People (EWGSOP), the Asian Working Group for Sarcopenia, the Foundation for the National Institutes of Health Sarcopenia Project, and the International Working Group on Sarcopenia (IWGS). Subgroup analyses by CKD stages, consensus, and gender were performed. Pooled prevalence was obtained from random‐effect models. A total of 140 studies (42 041 patients) across 25 countries were included in this systematic review and meta‐analyses. Global prevalence of sarcopenia was 24.5% [95% confidence interval (CI): 20.9–28.3) and did not differ among stages (P = 0.33). Prevalence varied according to the consensus definition from 11% to 30%, with no significant difference (P = 0.42). Prevalence of severe sarcopenia was 21.0% (95% CI: 11.7–32.0), with higher rates for patients on dialysis (26.2%, 95% CI: 16.6–37.1) compared to non‐dialysis (3.0%, 95% CI: 0–11.1; P < 0.01). Sarcopenic obesity was observed in 10.8% (95% CI: 3.5–21.2). Regarding sarcopenia traits, low muscle strength was found in 43.4% (95%CI: 35.0–51.9), low muscle mass in 29.1% (95% CI: 23.9–34.5), and low physical performance in 38.6 (95% CI: 30.9–46.6) for overall CKD. Prevalence was only higher in patients on dialysis (50.0%, 95% CI: 41.7–57.4) compared to non‐dialysis (19.6%, 95% CI: 12.8–27.3; P < 0.01) for low muscle strength. We found a high global prevalence of sarcopenia in the wide spectrum of CKD. Low muscle strength, the primary sarcopenia trait, was found in almost half of the overall population with CKD. Patients on dialysis were more prevalent to low muscle strength and severe sarcopenia. Nephrology professionals should be aware of regularly assessing sarcopenia and its traits in patients with CKD, especially those on dialysis.

Background: Sarcopenia, a degenerative and generalized skeletal muscle disorder involving the loss of muscle function and mass, is an under‐recognized problem in clinical practice, particularly in chronic kidney disease (CKD). We aimed to investigate the prevalence of sarcopenia in individuals with CKD, its risk factors, and its association with all‐cause mortality and progression to end‐stage renal disease (ESRD). Methods: UK Biobank participants were grouped according to the presence of CKD (defined as an estimated glomerular filtration rate <60 mL/min/1.73 m ² ) and as having probable (low handgrip strength), confirmed (plus low muscle mass), and severe sarcopenia (plus poor physical performance) based on the 2019 European Working Group of Sarcopenia in Older People and Foundation for the National Institutes of Health criteria. Risk factors were explored using logistic regression analysis. Survival models were applied to estimate risk of mortality and ESRD. Results: A total of 428 320 participants, of which 8767 individuals with CKD (46% male, aged 62.8 (standard deviation 6.8) years, median estimated glomerular filtration rate 54.5 (interquartile range 49.0–57.7) mL/min/1.72 m ² ) were included. Probable sarcopenia was present in 9.7% of individuals with CKD compared with 5.0% in those without ( P < 0.001). Sarcopenia was associated with being older; inflammation; poorer renal function; and lower serum albumin, total testosterone, and haemoglobin. The largest risk factors for sarcopenia were having three or more comorbidities (odds ratio: 2.30; 95% confidence interval: 1.62 to 3.29; P < 0.001) and physical inactivity: participants in the highest quartile of weekly activity were 43% less likely to have sarcopenia compared to the lowest quartile (odds ratio: 0.57; 0.42 to 0.76; P < 0.001). Participants with CKD and sarcopenia had a 33% (7% to 66%; P = 0.011) higher hazard of mortality compared with individuals without. Sarcopenic CKD individuals had a 10 year survival probability of 0.85 (0.82 to 0.88) compared with 0.89 (0.88 to 0.30) in those without sarcopenia, an absolute difference of 4%. Those with sarcopenia were twice as likely to develop ESRD (hazard ratio: 1.98; 1.45 to 2.70; P < 0.001). Conclusions: Participants with reduced kidney function are at an increased risk of premature mortality. The presence of sarcopenia increases the risk of mortality and ESRD. Appropriate measurement of sarcopenia should be used to identify at‐risk individuals. Interventions such as physical activity should be encouraged to mitigate sarcopenia.

Background: People with chronic kidney disease (CKD) report high levels of physical inactivity, a major modifiable risk factor for morbidity and mortality. Understanding the biological, psychosocial and demographic causes of physical activity behaviour is essential for the development and improvement of potential health interventions and promotional initiatives. This study investigated the prevalence of physical inactivity and determined individual correlates of this behaviour in a large sample of patients across the spectrum of kidney disease. Methods: A total of 5656 people across all stages of CKD (1–2, 3, 4–5, haemodialysis, peritoneal dialysis and renal transplant recipients) were recruited from 17 sites in England from July 2012 to October 2018. Physical activity was evaluated using the General Practice Physical Activity Questionnaire. Self-reported cardiorespiratory fitness, self-efficacy and stage of change were also assessed. Binominal generalized linear mutually adjusted models were conducted to explore the associations between physical activity and correlate variables. This cross-sectional observational multi-centre study was registered retrospectively as ISRCTN87066351 (October 2015). Results: The prevalence of physical activity (6–34%) was low and worsened with disease progression. Being older, female and having a greater number of comorbidities were associated with greater odds of being physically inactive. Higher haemoglobin, cardiorespiratory fitness and self-efficacy levels were associated with increased odds of being active. Neither ethnicity nor smoking history had any effect on physical activity. Conclusions: Levels of physical inactivity are high across all stages of CKD. The identification of stage-specific correlates of physical activity may help to prioritize factors in target groups of kidney patients and improve the development and improvement of public health interventions.

Objective: People with nondialysis-dependent chronic kidney disease (CKD) and renal transplant recipients (RTRs) have compromised physical function and reduced physical activity (PA) levels. Whilst established in healthy older adults and other chronic diseases, this association remains underexplored in CKD. We aimed to review the existing research investigating poor physical function and PA with clinical outcome in nondialysis CKD. Data sources: Electronic databases (PubMed, MEDLINE, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials) were searched until December 2017 for cohort studies reporting objective or subjective measures of PA and physical function and the associations with adverse clinical outcomes and all-cause mortality in patients with nondialysis CKD stages 1–5 and RTRs. The protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42016039060). Review methods: Study quality was assessed using the Newcastle-Ottawa Scale and the Agency for Healthcare and Research Quality (AHRQ) standards. Results: A total of 29 studies were included; 12 reporting on physical function and 17 on PA. Only eight studies were conducted with RTRs. The majority were classified as ‘good’ according to the AHRQ standards. Although not appropriate for meta-analysis due to variance in the outcome measures reported, a coherent pattern was seen with higher mortality rates or prevalence of adverse clinical events associated with lower PA and physical function levels, irrespective of the measurement tool used. Sources of bias included incomplete description of participant flow through the study and over reliance on self-report measures. Conclusions: In nondialysis CKD, survival rates correlate with greater PA and physical function levels. Further trials are required to investigate causality and the effectiveness of physical function and PA interventions in improving outcomes. Future work should identify standard assessment protocols for PA and physical function.