Rong Xu

Gender differences in age-related decline in glomerular filtration rates in healthy people and chronic kidney disease patients

BackgroundSince men with chronic kidney disease (CKD) progress faster than women, an accurate assessment of CKD progression rates should be based on gender differences in age-related decline of glomerular filtration rate (GFR) in healthy individuals.MethodsA Chinese sample population from a stratified, multistage, and clustered CKD screening study was classified into healthy, at-risk, and CKD groups. The gender differences in estimated GFR (eGFR) and age-related eGFR decline were calculated for each group after controlling for blood pressure, fasting glucose levels, serum lipids levels, education level, and smoking status. After referencing to the healthy group, gender-specific multivariate-adjusted rates of decline in eGFR and differences in the rates of decline were calculated for both CKD and at-risk groups.ResultsThe healthy, at-risk, and CKD groups consisted of 4569, 7434, and 1573 people, respectively. In all the 3 groups, the multivariate-adjusted eGFRs in men were lower than the corresponding eGFRs in women. In addition, in the healthy and at-risk groups, the rates of decline in eGFR in men were lower than the corresponding rates of decline in women (healthy group: 0.51 mL·min-1·1.73 m-2·yr-1vs. 0.74 mL·min-1·1.73 m-2·yr-1 and at-risk group: 0.60 mL·min-1·1.73 m-2·yr-1vs. 0.73 mL·min-1·1.73 m-2·yr-1). However, in the CKD group, the rates of decline in eGFR in men were similar to those in women (0.96 mL·min-1·1.73 m-2·yr-1vs. 0.91 mL·min-1·1.73 m-2·yr-1). However, after referencing to the healthy group, the rates of decline in eGFR in men in the at-risk and CKD groups were greater faster than the corresponding rates in women (at-risk group: 0.10 mL·min-1·1.73 m-2·yr-1vs. -0.03 mL·min-1·1.73 m-2·yr-1 and CKD group: 0.44 mL·min-1·1.73 m-2·yr-1vs. 0.15 mL·min-1·1.73 m-2·yr-1).ConclusionTo accurately assess gender differences in CKD progression rates, gender differences in age-related decline in GFR should be considered.

Impact of Individual and Environmental Socioeconomic Status on Peritoneal Dialysis Outcomes: A Retrospective Multicenter Cohort Study

Objectives We aimed to explore the impacts of individual and environmental socioeconomic status (SES) on the outcome of peritoneal dialysis (PD) in regions with significant SES disparity, through a retrospective multicenter cohort in China. Methods Overall, 2,171 incident patients from seven PD centers were included. Individual SES was evaluated from yearly household income per person and education level. Environmental SES was represented by regional gross domestic product (GDP) per capita and medical resources. Undeveloped regions were defined as those with regional GDP lower than the median. All-cause and cardiovascular death and initial peritonitis were recorded as outcome events. Results Poorer PD patients or those who lived in undeveloped areas were younger and less-educated and bore a heavier burden of medical expenses. They had lower hemoglobin and serum albumin at baseline. Low income independently predicted the highest risks for all-cause or cardiovascular death and initial peritonitis compared with medium and high income. The interaction effect between individual education and regional GDP was determined. In undeveloped regions, patients with an elementary school education or lower were at significantly higher risk for all-cause death but not cardiovascular death or initial peritonitis compared with those who attended high school or had a higher diploma. Regional GDP was not associated with any outcome events. Conclusion Low personal income independently influenced all-cause and cardiovascular death, and initial peritonitis in PD patients. Education level predicted all-cause death only for patients in undeveloped regions. For PD patients in these high risk situations, integrated care before dialysis and well-constructed PD training programs might be helpful.

Comparison of the prevalence of chronic kidney disease among different ethnicities: Beijing CKD survey and American NHANES

BACKGROUNDnIt is unclear whether ethnic disparity of the prevalence of chronic kidney disease (CKD) exists among native Chinese and American ethnicities.nnnMETHODSnA stratified multistage clustered screening for CKD performed in Beijing in 2006 was compared with data from the National Health and Nutrition Examination Survey (NHANES) between 1999-2006 (participants aged > or =20 years, 13 626 Chinese, 9006 whites, 3447 African Americans, 4626 Hispanics). Serum creatinine from Beijing and NHANES were calibrated at the Cleveland Clinic Laboratory. The re-expressed abbreviated MDRD equation for Americans and its modified form for Chinese were used to estimate glomerular filtration rate (eGFR). Subjects with eGFR <60 mL/min/1.73 m(2) were diagnosed as having chronic renal insufficiency (CRI). Albuminuria was diagnosed if the urine albumin-creatinine ratio was >17 mg/g for males or >25 mg/g for females. CKD was diagnosed if CRI or albuminuria was present.nnnRESULTSnCompared with American whites, African Americans and Hispanics, Chinese had a lower prevalence of adjusted albuminuria (12.10%, 16.33% and 14.16% versus 9.27%), CRI (9.46%, 5.18% and 3.11% versus 1.38%) and CKD (19.03%, 19.00% and 15.99% versus 10.25%). Moreover, Chinese hold the lowest risk of albuminuria when exposed to diabetes; the risk of CRI among Chinese when exposed to diabetes or hypertension was lower than that among African Americans, but similar to that among whites and Hispanics.nnnCONCLUSIONSnThe CKD prevalence was significantly different among native Chinese and American ethnicities.

Daily protein intake and survival in patients on peritoneal dialysis

BACKGROUNDnThe decreased protein intake may lead to protein-energy wasting and poor survival. It is unknown what the appropriate protein intake in patients on peritoneal dialysis (PD) is. We aimed to explore the appropriate levels of daily protein intake (DPI) in favor of outcome in a large PD cohort.nnnMETHODSnOur study enrolled 305 incident patients, who could be followed regularly. Demographic data were collected at baseline. Biochemical, dietary and nutritional data and dialysis adequacy were measured at the baseline and thereafter at regular intervals. Outcome events included all-cause death, cardiovascular disease (CVD) death and first-episode peritonitis.nnnRESULTSnA total of 127 patients died during the 44.5-month follow-up, 41.7% of whom died from CVD. A total of 129 cases first-episode peritonitis were observed. Patients with a high tertile of baseline DPI (≥ 0.94 g/kg/day) had significantly higher serum albumin, prealbumin, hemoglobin, lean body mass and handgrip strength compared to the low tertile group (≤ 0.73 g/kg/day) (P < 0.05-0.001). They also had significantly lower risk for all-cause, CVD death and first-episode peritonitis than the low tertile group adjusted for commonly recognized confounders. Although patients in the middle tertile of DPI (0.74-0.93 g/kg/day) did not show significant differences in the majority of nutritional markers, all-cause and CVD mortality compared to high tertile group, they had a trend to a negative nitrogen balance and similar risk for first-episode peritonitis to the low tertile group. The DPI included as a time-dependent variable could not predict any outcome events in multivariate Cox models.nnnCONCLUSIONSnOur study revealed that DPI <0.73 g/kg/day was associated with protein-energy wasting and worst outcome for PD patients. The DPI >0.94 g/kg/day was in favor of nutrition status and long-term outcome in this population.

The Associations of Uric Acid, Cardiovascular and All-Cause Mortality in Peritoneal Dialysis Patients

Aims To investigate whether uric acid (UA) is an independent predictor of cardiovascular (CV) and all-cause mortality in peritoneal dialysis (PD) patients after controlling for recognized CV risk factors. Methods A total of 2264 patients on chronic PD were collected from seven centers affiliated with the Socioeconomic Status on the Outcome of Peritoneal Dialysis (SSOP) Study. All demographic and laboratory data were recorded at baseline. Multivariate Cox regression was used to calculate the hazard ratio (HR) of CV and all-cause mortality with adjustments for recognized traditional and uremia-related CV factors. Results There were no significant differences in baseline characteristics between patients with (nu200a=u200a2193) and without (nu200a=u200a71) UA measured. Each 1 mg/dL of increase in UA was associated with higher all-cause mortality with 1.05(1.00∼1.10) of HR and higher CV mortality with 1.12 (1.05∼1.20) of HR after adjusting for age, gender and center size. The highest gender-specific tertile of UA predicted higher all-cause mortality with 1.23(1.00∼1.52) of HR and higher CV mortality with 1.69 (1.21∼2.38) of HR after adjusting for age, gender and center size. The predictive value of UA was stronger in patients younger than 65 years without CV disease or diabetes at baseline. The prognostic value of UA as both continuous and categorical variable weakened or disappeared after further adjusted for uremia-related and traditional CV risk factors. Conclusions The prognostic value of UA in CV and all-cause mortality was weak in PD patients generally, which was confounded by uremia-related and traditional CV risk factors.

Gender-specific reference value of urine albumin-creatinine ratio in healthy Chinese adults : Results of the Beijing CKD survey

BACKGROUNDnThe reference value of urine albumin-creatinine ratio (ACR) has racial disparities. The ACR reference value in a healthy Beijing population is reported.nnnMETHODSnA reference Beijing population was sampled via a multistage, clustered complex sampling method. By excluding subjects with self-reported kidney disease, hypertension, diabetes, dyslipidemia, cardiovascular disease, obesity or underweight condition, overt proteinuria, hematuria, or pyuria, as well as those with an estimated glomerular filtration rate (eGFR) > 200ml/min/1.73m2 or < 60ml/min/1.73m2, apparently healthy subjects (1260 males, 2305 females, aged 18-84y) were selected to be included in the current analysis. Urine albumin was measured using the immunoturbidimetic method, creatinine was measured using Jaffes kinetic method on a morning spot-urine sample, and ACR was calculated. The 95th percentile of ACR was used as the normal upper limit. The association between ACR and each of gender, age, systolic blood pressure, body mass index, serum glucose, lipids, and eGFR was examined.nnnRESULTSnThe normal upper limit of ACR was 14mg/g (1.58mg/mmol) for males and 20mg/g (2.26mg/mmol) for females. Females had higher ACR values than males, and age, systolic blood pressure, and eGFR were positively correlated with ACR.nnnCONCLUSIONSnThe ACR reference value in the healthy Beijing population is lower than that of the Western population. Age, systolic blood pressure, and eGFR were found to correlate with ACR.

Hyponatremia and Cognitive Impairment in Patients Treated with Peritoneal Dialysis

BACKGROUND AND OBJECTIVESnHyponatremia has been identified as a relevant factor for cognitive impairment but has not been investigated in patients receiving peritoneal dialysis (PD). This study investigated the relationship between hyponatremia and cognitive functions in PD patients.nnnDESIGN, SETTING, PARTICIPANTS, & MEASUREMENTSnA total of 476 clinically stable patients from five PD units who were older than 18 years of age and had undergone PD for at least 3 months between March 2013 and March 2014 were enrolled in this multicenter cross-sectional study. Global cognitive function was measured using the Modified Mini-Mental State Examination (3MS); executive function, by trail making tests A (trails A) and B (trails B); and immediate memory, delayed memory, and language ability, by subtests of Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Hyponatremia was defined as serum sodium level ≤135 mmol/L, which was calculated as the mean of measurements taken over the preceding 3 months.nnnRESULTSnFifty patients (10.5%) had hyponatremia; these patients tended to be older and less educated, to have less inflammation, and to have the higher prevalence of cognitive impairment. They also had lower scores on RBANS subtests. After adjustment for demographic and clinical confounders, hyponatremia was independently associated with lower 3MS score (coefficient, -5.28; 95% confidence interval [CI], -8.44 to -2.13) and longer completion time of trials A (coefficient, 22.68; 95% CI, 3.44 to 41.92) and B (coefficient, 45.56; 95% CI, 1.30 to 89.81). After additional adjustment for laboratory measures, hyponatremia was still associated with 3MS score and completion time of trails A. Hyponatremia was independently associated with CI (odds ratio, 2.17; 95% CI, 1.02 to 4.94) and executive dysfunction (odds ratio, 2.43; 95% CI, 1.01 to 5.87) using multivariate logistic regression analysis. Sensitivity analyses with multivariable models that included propensity score still supported the association between hyponatremia and cognitive impairment.nnnCONCLUSIONSnHyponatremia was associated with global and specific cognitive impairment in PD patients.

Peritoneal Protein Leakage, Systemic Inflammation, and Peritonitis Risk in Patients on Peritoneal Dialysis

♦ Background: Whether peritoneal protein leakage predicts risk for peritonitis in patients on peritoneal dialysis (PD) is unknown. In this observational cohort study, we aimed to determine that association and, further, to explore if it might be explained by systemic inflammation. ♦ Methods: We prospectively followed 305 incident PD patients to first-episode peritonitis, censoring, or the end of the study. Demographics, comorbidity score, biochemistry, and peritoneal protein clearance (PrC) were collected at baseline. The predictors of first-episode peritonitis were analyzed prospectively. ♦ Results: During follow-up, 14 868 patient months and 251 episodes of peritonitis were observed. The baseline PrC was 73.2 mL/day (range: 53.2 - 102 mL/day). Patients with a high PrC were prone to be older and malnourished. They also had a higher comorbidity score and higher C-reactive protein values. In 132 first episodes of peritonitis, baseline PrC was shown to be a significant independent predictor after adjustment for age, sex, body mass index, diabetes, residual renal function, hemoglobin, and peritoneal transport rate. Systemic inflammatory markers such as serum albumin, C-reactive protein, and interleukin-6 could not explain the association of PrC and high risk for peritonitis. ♦ Conclusions: Baseline peritoneal protein leakage was able to independently predict risk for peritonitis, which is not explained by systemic inflammation. The underlying mechanisms should be explored in future.

Clinical characteristics and outcomes of peritoneal dialysis-related peritonitis with different trends of change in effluent white cell count: a longitudinal study.

♦ Background: Effluent white cell count (WCC) is among the important prognostic factors for peritonitis outcome, but its trend has never been studied. We aimed to explore the clinical characteristics and outcomes of peritonitis episodes having different trends in effluent WCC change in the first 5 days. ♦ Methods: For each peritonitis episode, we examined the patient’s demographic and biochemical data, serial effluent WCC, and organisms cultured. Peritonitis-associated death and transfer to hemodialysis were defined as treatment failure. ♦ Results: Based on the trend of effluent WCC in the first 5 days, we divided 190 peritonitis episodes into group A (WCC persistently declined), group B (WCC declined after a transient increase), group C (WCC increased after a transient decline), and group D (WCC persistently increased). In group A, peritonitis was caused mostly by gram-positive organisms, and effluent WCC declined the most quickly, leading to a good prognosis. Although the elevation of effluent WCC was prolonged in group B, and the infections were, compared with those in group A, more often caused by gram-negative organisms, outcomes were not worse. In group C, the effluent WCC was more likely to be higher than 100/μL on day 5, and the infection was, compared with those in groups A and B, less likely to be caused by gram-positive organisms. Accordingly, membership in group C independently predicted the worst outcome of peritonitis even adjusted for age, sex, and causative organism. ♦ Conclusions: Different trends of change in effluent WCC during the early stage of peritonitis represent different clinical patterns and outcomes. Further investigation for optimizing outcomes is required.

Disease severity score could not predict the outcomes in peritoneal dialysis-associated peritonitis

BACKGROUNDnWe aim to explore if disease severity score (DSS) at onset is associated with dialysate white cell counts, the severity of causative organisms and the risk for treatment failure of peritoneal dialysis (PD)-associated peritonitis in an adult PD cohort.nnnMETHODSnOur prospective cohort study recorded all peritonitis episodes between 2008 and 2010. The DSS, demographic data and clinical characteristics were recorded at the onset of peritonitis. The dialysate cells were counted at regular intervals and organism culture were examined too. Treatment failure of peritonitis was defined as peritonitis-associated death and transfer to haemodialysis.nnnRESULTSnA total of 219 episodes of peritonitis in 146 PD patients were recorded, 21.9% of which resulted in treatment failure. There were no significant differences in dialysate white cell counts on the fifth and seventh day and the distribution of causative organism between groups with varied DSS level. DSS could not predict treatment failure including peritonitis-related death and transfer to haemodialysis after adjusting for age, gender, diabetes, dialysis duration, dialysate white cell count on the third day, the presence of Staphylococcus aureus, gram-negative organisms and polymicrobial organisms.nnnCONCLUSIONnOur study demonstrated that DSS at onset was not associated with prolonged elevation of dialysate white cell counts, severity of causative organisms and outcome of peritonitis episodes in adult PD patients.