Metabolic syndrome in peritoneal dialysis patients: choice of diagnostic criteria and prognostic implications

Prevalence of metabolic syndrome in patients with end-stage renal disease: a systematic review and meta-analysis

BACKGROUND

Metabolic syndrome, a significant risk factor for cardiovascular mortality in patients with end-stage renal disease, profoundly impacts patient prognosis and survival. Despite its clinical importance, the prevalence of metabolic syndrome remains unexplored in this population. Therefore, the objective of this study was to systematically assess the prevalence of metabolic syndrome among patients with end-stage renal disease and raise awareness among healthcare professionals.

METHODS

We conducted a comprehensive search in CNKI, WANFANG, WeiPu, CBM, PubMed, Web of Science, EMBASE, and The Cochrane Library databases. The search time was until August 21, 2023. Standardized tables were employed for data extraction and imported into Stata 16.0 software for subsequent meta-analysis. A random-effects model was employed to estimate combined prevalence and 95% confidence intervals. Subgroup and sensitivity analyses were conducted to explore potential sources of heterogeneity, while publication bias was evaluated using a funnel plot and Egger's test. This study has been registered with PROSPERO under the registration number CRD42023456284.

RESULTS

This meta-analysis comprised 35 studies involving a total of 14,202 participants. The pooled prevalence estimate for metabolic syndrome was 49.0% [95% CI (46.0,53.0)]. We conducted subgroup analyses based on participant characteristics, gender distribution, publication year, national economic status, diagnostic criteria employed, and components of metabolic syndrome.

CONCLUSIONS

The prevalence of metabolic syndrome is higher among patients with end-stage renal disease, necessitating early prevention and control measures to reduce its incidence and delay the progression of the disease, thereby improving patient life expectancy.

Relationship between serum iPTH and peritonitis episodes in patients undergoing continuous ambulatory peritoneal dialysis

BACKGROUND

Peritonitis is considered as one of the most serious complications that cause hospitalization in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). There is limited evidence on the impact of the parathyroid hormone (PTH) on the first peritoneal dialysis (PD)-associated peritonitis episode. We aimed to investigate the influence of serum intact parathyroid hormone (iPTH) on peritonitis in patients undergoing PD.

METHODS

This was a retrospective cohort study. Patients undergoing initial CAPD from a single center in China were enrolled. The baseline characteristics and clinical information were recorded. The primary outcome of interest was the occurrence of the first PD-associated peritonitis episode. Five Cox proportional hazard models were constructed in each group set. In group set 1, all participants were divided into three subgroups by tertiles of the serum concentration of iPTH; in group set 2, all participants were divided into three subgroups based on the serum concentration of iPTH with 150 pg/ml interval (<150, 150-300, and >300 pg/ml). Hazard ratios and 95% confidence intervals (CIs) were calculated for each model. The multivariate linear regression analysis elimination procedure assessed the association between the clinical characteristics at baseline and the iPTH levels. Restricted cubic spline models were constructed, and stratified analyses were also conducted.

RESULTS

A total of 582 patients undergoing initial PD (40% women; mean age, 45.1 ± 11.5 years) from a single center in China were recruited. The median follow-up duration was 25.3 months. Multivariate Cox regression analysis showed that, in the fully adjusted model, a higher serum iPTH level (tertile 3, iPTH >300 pg/ml) was significantly associated with a higher risk of PD-associated peritonitis at 3 years [tertile 3: hazard ratio (HR) = 1.53, 95%CI = 1.03-2.55, p = 0.03; iPTH > 300 pg/ml: HR = 1.57, 95%CI = 1.08-2.27, p = 0.02]. The hazard ratio for every 100 pg/ml increase in serum iPTH level was 1.12 (95%CI = 1.05-1.20, p < 0.01) in the total cohort when treating iPTH as a continuous variable.

CONCLUSIONS

An elevated iPTH level was significantly associated with an increased risk of peritonitis in patients undergoing CAPD.

Obesity, Weight Gain, and Fluid Overload in Peritoneal Dialysis

Obesity is a global epidemic that has a complicated pathogenesis as well as impact on the outcome of peritoneal dialysis (PD) patients. In this review, the prevalence of obesity in incident PD patients as well as the phenomenon of new-onset glucose intolerance after PD will be reviewed. Published literature on the effect of obesity on the survival and incidence of cardiovascular disease in PD patients will be discussed. Particular emphasis would be put on literature that compared the impact of obesity on the outcome of hemodialysis and PD, and the confounding effect of dialysis adequacy. Next, the complex concept of obesity and its relevance for PD will be explored. The focus would be put on the methods of assessment and clinical relevance of central versus general obesity, as well as visceral versus subcutaneous adipose tissue. The relation between obesity and systemic inflammation, as well as the biological role of several selected adipokines will be reviewed. The confounding effects of metabolic syndrome and insulin resistance will be discussed, followed by the prevalence and prognostic impact of weight gain during the first few years of PD. The differences between weight gain due to fluid overload and accumulation of adipose tissue will be discussed, followed by the current literature on the change in body composition after patients are put on chronic PD. The methods of body composition will be reviewed, and the clinical relevance of individual body component (fluid, fat, muscle, and bone) will be discussed. The review will conclude by highlighting current gaps of knowledge and further research directions in this area.

Insulin resistance in cardiovascular disease, uremia, and peritoneal dialysis

Diabetic nephropathy is highly correlated with the occurrence of other complications of type 1 diabetes (T1D) and type 2 diabetes (T2D) mellitus; for example, hypertension with cardiovascular disease (CVD) being the most frequent cause of death in patients with end-stage renal disease and undergoing renal dialysis. Hyperglycemia and insulin resistance (IR) are responsible for the micro- and macrovascular complications of diabetes through different mechanisms. In particular, IR plays a key role in the etiology of atherosclerosis in both diabetic and non-diabetic patients. IR - exacerbated by organ-level selectivity - is more important than glycemic control per se in determining cardiovascular outcomes. This may be exacerbated by the fact that IR is organ and pathway specific due to the only selective loss of sensitivity to insulin action of specific pathways/processes. Therefore, it is counterintuitive that the use of peritoneal dialysis (PD) in (frequently) diabetic renal disease patients should involve their exposure to high daily doses of glucose peritoneally. In view of the controversy about the causal association between glucose load and CVD in PD patients, we discuss the role that selective IR may play in the progression of CVD in diabetic renal end-stage patients. In discussing these associations, we propose that reducing glucose exposure in PD solutions may be beneficial especially if coupled with strategies that address IR directly, and the avoidance of excessive use of insulin treatment in T2D.

An Aging Population of Chronic Hepatitis B With Increasing Comorbidities: A Territory-Wide Study From 2000 to 2017

Patients with chronic hepatitis B (CHB) are aging because of improved survival under better health care. This has an important implication on the choice of antiviral treatment (AVT), given that long-term safety would be a concern in the presence of multiple comorbidities. We aimed to determine the prevalence of key comorbidities and concomitant medications in a territory-wide CHB cohort in Hong Kong in 2000-2017. CHB patients who have been under the care at primary, secondary, and tertiary medical centers in the public sector were identified through the Clinical Data Analysis and Reporting System of the Hospital Authority, Hong Kong. The demographics and prevalence of key comorbidities, including diabetes mellitus, hypertension, chronic kidney disease, osteopenia/osteoporosis based on diagnosis codes, relevant medications, and/or laboratory parameters, were determined according to CHB patients' first appearance in four time periods: 2000-2004, 2005-2009, 2010-2013, and 2014-2017. In the final analysis, 135,395 CHB patients were included; the mean age increased with time: 41 ± 15 years in 2000-2004; 46 ± 17 years in 2005-2009; 51 ± 16 years in 2010-2013; and 55 ± 15 years in 2014-2017. There was a trend of increasing prevalence of several common comorbidities over the four periods: hypertension 25.5%, 23.8%, 27.2%, and 28.6%; diabetes mellitus 10.6%, 12.5%, 16.1%, and 20.1%; cardiovascular disease 12.5%, 16.9%, 20.9%, and 22.2%; and malignancy 7.0%, 13.2%, 17.3%, and 23.6%, respectively (all P < 0.001). Conclusion: CHB patients are getting older with increasing prevalence of common comorbidities. These comorbidities should be taken into account when choosing AVT.

Clinical characterization and prognostic implications of metabolic syndrome in patients undergoing peritoneal dialysis at a Chinese center

Objective

Metabolic syndrome (MS) is a common clinical condition associated with cardiovascular disease in patients undergoing peritoneal dialysis (PD); however, its prognostic implication among patients receiving PD remains controversial.

Methods

In a prospective study from January 2013 and June 2016, we enrolled 190 patients undergoing PD and followed them for 46.4 ± 30.7 months. We assessed the associations of clinical characteristics and measurements with diabetes mellitus (DM) status, MS, and prognostic outcomes among the included patients.

Results

We found that DM was associated with shortened duration of dialysis and poor survival. The prevalence of MS was 58.9% among all patients. We found significant differences in age, body weight, body mass index, triglycerides, high-density lipoprotein cholesterol, fasting plasma glucose, leukocytes, platelets, neutrophil percentage, and pre-albumin between patients with and without MS. We found a negative correlation trend between serum intact parathyroid hormone and MS among our patients. The arteriosclerosis index was significantly elevated in the MS group compared with the non-MS group. Serum calcium concentration and frequency of hospital admissions were significantly associated with mortality and technique failure.

Conclusions

MS was positively associated with cardiovascular disease. DM, and hypocalcemia. Frequent hospital admissions can predict poor prognosis in patients undergoing PD.

Metabolic Syndrome and Mortality in Continuous Ambulatory Peritoneal Dialysis Patients: A 5-Year Prospective Cohort Study

Background/Aims: Metabolic syndrome (MS) has been widely proved as a predictor of cardiovascular disease, all-cause, and cardiovascular mortality in general population. But its effects on mortality and technique failure have not been well illustrated in peritoneal dialysis (PD) patients. We aimed to investigate the association of MS and clinical outcomes in Chinese continuous ambulatory PD (CAPD) patients. Methods: A single-center, prospective, observational cohort study was conducted in CAPD patients enrolled from September 1 to December 31, 2011, and followed up until December 31, 2016. Demographic, clinical, biochemical and anthropological data were collected. The relationships between MS and mortality and technique failure were assessed using Kaplan-Meier and Cox Regression Survival Functions. Results: A total of 511 patients were enrolled. The baseline mean age was 48.4 ± 14.4 years, 282 patients (55.2%) were male, and 130 patients (25.4%) were diabetic. In total, 213 patients (41.7%) met the diagnostic criterion of MS. During a median of 4.4 years (interquartile range 2.3–5.3 years) follow-up period, 114 patients died, of whom, 65 patients (48%) died in MS group versus 49 patients (30%) in non-MS group. Patients who died tended to be older, higher in inflammation markers and with poorer nutritional state. Kaplan-Meier Survival Functions found patients with MS had a significant rising of all-cause mortality (log-rank test = 12.811, p < 0.001) and cardiovascular mortality (log-rank test = 14.529, p < 0.001) in all patients, and a significant rising of cardiovascular mortality (log-rank test = 4.486, p = 0.034) in non-diabetic patients. After adjusting for confounders, Cox Regression showed that MS was significantly associated with higher cardiovascular mortality in all patients (hazard ratio [HR] 2.21, 95% CI 1.12–4.36, p = 0.022) and in non-diabetic patients (HR 2.60, 95% CI 1.07–6.35, p = 0.036), but it has no significant effect on technique failure. Conclusion: In CAPD patients, MS predicted mortality, especially cardiovascular mortality. No relationship was found between MS and technique survival.

Clinical Studies of Interventions to Mitigate Cardiovascular Risk in Peritoneal Dialysis Patients

Cardiovascular disease (CVD) is highly prevalent in the peritoneal dialysis (PD) population, affecting up to 60% of cohorts. CVD is the primary cause of death in up to 40% of PD patients in Australia, New Zealand, and the United States. Cardiovascular mortality rates are reported to be approximately 14 per 100 patient-years, which are 10- to 20-fold greater than those of age- and sex-matched controls. The excess risk of CVD is related to a combination of traditional risk factors (such as hypertension, dyslipidemia, obesity, smoking, sedentary lifestyle, and insulin resistance), nontraditional (kidney disease-related) risk factors (such as anemia, chronic volume overload, inflammation, malnutrition, hyperuricemia, and mineral and bone disorder), and PD-specific risk factors (such as dialysis solutions, glycation end products, hypokalemia, residual kidney function, and ultrafiltration failure). Interventions targeting these factors may mitigate cardiovascular risk, although high-level clinical evidence is lacking. This review summarizes the evidence relating to cardiovascular interventions targeting modifiable CVD risk factors in PD patients, as well as highlighting the key recommendations of the International Society for Peritoneal Dialysis Cardiovascular and Metabolic Guidelines.

Insulin resistance in chronic kidney disease

This review provides an overview of insulin resistance (IR) in patients with chronic kidney disease (CKD). IR is a pathological state in which target tissues fail to respond normally to insulin. IR is understood as a consequence of CKD and its prevalence rises particularly in advanced CKD stages. Mechanisms leading to IR are complex and multifactorial, involving post-receptor signaling defects, unhealthy lifestyles, metabolic acidosis, inflammation, oxidative stress, vitamin D deficiency, anemia, and uremic toxicity, as shown by human and experimental studies over the last 30 years. Whereas hyperinsulinemic euglycemic clamp is the gold standard, it is unpractical at the bedside, and either estimated IR indices by fasting glucose or insulin and oral glucose tolerance tests (OGTT) provide satisfactory estimates of IR also in patients with CKD. IR is likely to play a key role in the development of cardiometabolic complications, but not all studies associate IR with the risk of cardiovascular events and death. Various interventions at the level of lifestyle modifications, adaptations in dialysis therapy (such as use of icodextrin based solutions) and pharmacological strategies such as thiazolidinediones or vitamin D therapy may improve IR in patient with CKD.

Associations of Adiponectin, Leptin Levels, and the Change of Body Composition in Patients on Peritoneal Dialysis: A Prospective Cohort Study

Background

Although the association between adipokines such as adiponectin, leptin, and body composition has been noted, whether they could predict the change of fat mass and lean body mass is unknown. We aimed to examine these associations in patients on peritoneal dialysis (PD) through a prospective cohort study.

Methods

Body composition (by dual-energy x-ray absorptiometry) including fat mass and lean body mass were examined at baseline and then at year 3. Serum leptin and adiponectin levels were measured. Demographic data, comorbidity, biochemical data, inflammation (high-sensitive C-reactive protein [hs-CRP]) and insulin resistance (homeostatic model assessment [HOMA-IR]) were also examined.

Results

At baseline, serum adiponectin levels were significantly inversely correlated with weight, lean body mass index (LBMI), fat mass index (FMI), lean body mass (LBM), and fat mass (FM) in 213 prevalent patients. At year 3, FMI, LBMI, FM, and the percentage of FM (FM%) increased while the percentage of LBM (LBM%) significantly decreased despite unchanged weight and LBM among the remaining 112 patients. After adjustment for demographic data, comorbidities, hs-CRP, HOMA-IR, and daily energy intake (DEI), serum adiponectin at baseline was not associated with increases in LBMI, FMI, and FM, but independently associated with an increase in FM% and a decrease in LBM%. The predictive effect of high-serum adiponectin level on mortality disappeared after adjusting for diabetes and cardiovascular disease. Serum leptin was not associated with any changes in body composition during the follow-up, nor with the mortality in this cohort.

Conclusions

A high adiponectin level could predict an increase in FM% and a decrease in LBM% during a 3-year follow-up in PD patients. Serum adiponectin could not independently predict mortality in PD patients.

Peritoneal and Systemic Responses of Obese Type II Diabetic Rats to Chronic Exposure to a Hyperbranched Polyglycerol-Based Dialysis Solution

Metabolic syndrome (MetS) is commonly observed among peritoneal dialysis (PD) patients, and hyperbranched polyglycerol (HPG) is a promising glucose-sparing osmotic agent for PD. However, the biocompatibility of a HPG-based PD solution (HPG) in subjects with MetS has not been investigated. This study compared the local and systemic effects of a HPG solution with conventional physioneal (PYS) and icodextrin (ICO) PD solutions in rats with MetS. Obese type 2 diabetic ZSF1 rats received a daily intraperitoneal injection of PD solutions (10 mL) for 3 months. The peritoneal membrane (PM) function was determined by ultrafiltration (UF), and the systemic responses were determined by profiling blood metabolic substances, cytokines and oxidative status. Tissue damage was assessed by histology. At the end of the 3-month treatment with PD solutions, PM damage and UF loss in both the PYS and ICO groups were greater than those in the HPG group. Blood analyses showed that compared to the baseline control, the rats in the HPG group exhibited a significant decrease only in serum albumin and IL-6 and a minor glomerular injury, whereas in both the PYS and ICO groups, there were more significant decreases in serum albumin, antioxidant activity, IL-6, KC/GRO (CXCL1) and TNF-α (in ICO only) as well as a more substantial glomerular injury compared to the HPG group. Furthermore, PYS increased serum creatinine, serum glucose and urine production. In conclusion, compared to PYS or ICO solutions, the HPG solution had less adverse effects locally on the PM and systemically on distant organs (e.g. kidneys) and the plasma oxidative status in rats with MetS.

Effects of Cholesterol Levels on Mortality in Patients with Long-Term Peritoneal Dialysis Based on Residual Renal Function

The effect of dyslipidemia on peritoneal dialysis (PD) patients based on the presence of residual renal function (RRF; renal creatinine clearance >2 mL/min/1.73 m²) is unknown. Data from the Taiwan Renal Registry Data System between 2005 and 2012 were analyzed to estimate the association between dyslipidemia and mortality in PD patients. Long-term PD patients (n = 8032) were divided into groups with (RRF; n = 2691, 33.5%) and without RRF (non-RRF; n = 5341, 66.5%). The primary outcome was three-year mortality, and multivariate Cox regression was used for survival analysis. After stratifying the total cholesterol (TC) level between the first and third years, the hazard ratio for mortality was estimated. In the non-RRF group, TC < 120 mg/dL was associated with independently increased risk of mortality. In the RRF group, low TC was not independently correlated with increased mortality, but TC > 285 mg/dL was associated with increased risk. PD patients with higher level of TC (>200 mg/dL) in both first and third years of dialysis had significantly lower risk of mortality. In this nationwide cohort study, PD patients without RRF who had low TC level had the highest mortality, in contrast to those with RRF. Malnutrition in long-term PD patients without RRF is an important issue to be monitored.

The Current State of Peritoneal Dialysis

Technical innovations in peritoneal dialysis (PD), now used widely for the long-term treatment of ESRD, have significantly reduced therapy-related complications, allowing patients to be maintained on PD for longer periods. Indeed, the survival rate for patients treated with PD is now equivalent to that with in-center hemodialysis. In parallel, changes in public policy have spurred an unprecedented expansion in the use of PD in many parts of the world. Meanwhile, our improved understanding of the molecular mechanisms involved in solute and water transport across the peritoneum and of the pathobiology of structural and functional changes in the peritoneum with long-term PD has provided new targets for improving efficiency and for intervention. As with hemodialysis, almost half of all deaths on PD occur because of cardiovascular events, and there is great interest in identifying modality-specific factors contributing to these events. Notably, tremendous progress has been made in developing interventions that substantially reduce the risk of PD-related peritonitis. Yet the gains have been unequal among individual centers, primarily because of unequal clinical application of knowledge gained from research. The work to date has further highlighted the areas in need of innovation as we continue to strive to improve the health and outcomes of patients treated with PD.

Metabolic syndrome and obesity in peritoneal dialysis

Metabolic syndrome (MS) refers to clustering of features related to increased risk of cardiovascular disease, which include obesity or central obesity, dyslipidemia, diabetes mellitus or insulin resistance, together with hypertension. The prevalence of MS in end-stage renal failure patients on peritoneal dialysis is quite common, ranging from 40% to 60%, depending on the population studied and the definition used. However, there are controversies about the clinical outcome of patients with MS, particularly in the area of obesity. Whether peritoneal dialysis predisposes patients to MS is another unsolved issue. Despite these controversies, preventing patients from developing MS is important, at least from a theoretical point of view.

Peritoneal Dialysis in Asia

BACKGROUND

There is a growing demand of dialysis in Asia for end-stage renal failure patients. Diabetes mellitus is the leading cause of end-stage renal failure in many countries in Asia.

SUMMARY

The growth of peritoneal dialysis (PD) in Asia is significant and seeing a good trend. With the enhanced practices of PD, the quality of care in PD in Asia is also improved. Overall, PD and hemodialysis (HD) are comparable in clinical outcome. There is a global trend in the reduction of peritonitis rates and Asian countries also witness such improvement. The socio-economic benefits of PD for end-stage renal failure patients in both urban and rural areas in the developed and developing regions of Asia are an important consideration. This can help to reduce the financial burden of renal failure in addressing the growing demand of patients on dialysis. Initiatives should be considered to further drive down the cost of PD in Asia.

KEY MESSAGES

Growing demand for dialysis by an increasing number of end-stage renal failure patients requires the use of a cost-effective quality dialysis modality. PD is found to be comparable to HD in outcome and quality. In most countries in Asia, PD should be more cost-effective than HD. A 'PD-first' or a 'PD as first considered therapy' policy can be an overall strategy in many countries in Asia in managing renal failure patients, taking the examples of Hong Kong and Thailand.

FACTS FROM EAST AND WEST

(1) PD is cheaper than HD and provides a better quality of life worldwide, but its prevalence is significantly lower than that of HD in all countries, with the exception of Hong Kong. Allowing reimbursement of PD but not HD has permitted to increase the use of PD over HD in many Asian countries like Hong Kong, Vietnam, Taiwan, Thailand, as well as in New Zealand and Australia over the last years. In the Western world, however, HD is still promoted, and the proportion of patients treated with PD decreases. Japan remains an exception in Asia where PD penetration is very low. Lack of adequate education of practitioners and information of patients might as well be reasons for the low penetration of PD in both the East and West. (2) Patient survival of PD varies between and within countries but is globally similar to HD. (3) Peritonitis remains the main cause of morbidity in PD patients. South Asian countries face specific issues such as high tuberculosis and mycobacterial infections, which are rare in developed Asian and Western countries. The infection rate is affected by climatic and socio-economic factors and is higher in hot, humid and rural areas. (4) Nevertheless, the promotion of a PD-first policy might be beneficial particularly for remote populations in emerging countries where the end-stage renal disease rate is increasing dramatically.

Abdominal Obesity and Mortality in Continuous Ambulatory Peritoneal Dialysis Patients

Background

The relationship between abdominal obesity (AO) and mortality in peritoneal dialysis (PD) patients is controversial.

Methods

The prevalence of AO in 84 PD patients was assessed in a cross-section manner and followed up for 9 years at a single center. AO was defined as a waist circumference (WC) of more than 90 cm in males or more than 80 cm in females. The patients were classified as either with AO(AO group) or without AO(nAO group).

Results

The AO group was older, contained more diabetics, more females, and had higher Charlson comorbidity index (aCCI) scores, BMI, and triglyceride and lower serum creatinine than the non-AO subjects. The follow-up duration was 53.2±34.4 months. At the end of the follow-up, eighteen patients (21.4%) were dead; 9 died of cardiovascular causes. The five year survival rate was 40.8%. Kaplan-Meier analysis revealed that both all-cause and cardiovascular-cause mortalities were similar in the AO and nAO groups. Multivariate analysis revealed the presence of AO not to be an independent risk factor of all-cause and cardiovascular-cause mortality.

Conclusion

AO itself might not be a risk factor for mortality in PD patients. Nevertheless, further prospective studies with a large number of patients will be needed to prove this.