Peritoneal dialysis in China: a story of growth and innovation

The Utility of Sonographic Assessment in Selecting Patients for Percutaneous Insertion of Peritoneal Dialysis Catheter

Background

Percutaneous insertion of peritoneal dialysis (PD) catheters by nephrologists is a safe and effective alternative to open surgical techniques. These patients are usually carefully selected due to anatomical considerations and medical comorbidities, with the current literature suggesting exclusion of patients with prior abdominal surgery.

Method

We conducted a retrospective cohort study of pre-dialysis patients who attended a preprocedural clinic in a tertiary center over 6 years. Procedural complications and catheter survival were assessed. Chi-squared test and Kaplan-Meier survival analysis were undertaken. Inpatient assessments were excluded.

Results

A total of 217 patients were assessed, of whom 171 (78.8%) were accepted for percutaneous PD catheter insertion by a nephrologist. The key exclusion criteria were: ( 1 ) the clinical presence of abdominal hernia ( p < 0.001), ( 2 ) ultrasound findings of skin to peritoneum depth of > 5.5 cm ( p < 0.001) and ( 3 ) ultrasound findings of impaired visceral slide test ( p < 0.001). Prior abdominal surgery was not a default exclusion criterion ( p = 0.1), as 63 patients (37%) with prior abdominal surgery, average of 1.3 prior surgeries per patient, were assessed as appropriate for the percutaneous procedure. There was no difference in the procedural complication rate and catheter survival between patients with and without prior abdominal surgery.

Conclusion

A comprehensive preprocedural assessment utilizing ultrasound permits an objective selection of patients for percutaneous insertion of PD catheters by nephrologists. This allowed for successful and safe percutaneous insertion of PD catheters in patients who may have otherwise been excluded, e.g., prior abdominal surgery, patients with large bilateral poly-cystic kidneys, and central obesity.

Development and Validation of Residual Kidney Function Estimating Equations in Dialysis Patients

RATIONALE & OBJECTIVE

Measurement of residual kidney function is recommended for the adjustment of the dialysis prescription, but timed urine collections are difficult and prone to errors. Equations to calculate residual kidney function from serum concentrations of endogenous filtration markers and demographic parameters would simplify monitoring of residual kidney function. However, few equations to estimate residual kidney function using serum concentrations of small solutes and low-molecular-weight proteins have been developed and externally validated.

STUDY DESIGN

Study of diagnostic test accuracy.

SETTING & PARTICIPANTS

823 Chinese peritoneal dialysis (PD) patients (development cohort) and 826 PD and hemodialysis patients from the Netherlands NECOSAD study (validation cohort).

TESTS COMPARED

Equations to estimate residual kidney function (estimated clearance [eCl]) using serum creatinine, urea nitrogen, cystatin C, β2-microglobulin (B2M), β-trace protein (BTP), and combinations, as well as demographic variables (age, sex, height, and weight). Equations were developed using multivariable linear regression analysis in the development cohort and then tested in the validation cohort. Equations were compared with published validated equations.

OUTCOMES

Residual kidney function measured as urinary clearance (mCl) of urea nitrogen (mClUN) and average of creatinine and urea nitrogen clearance (mClUN-cr).

RESULTS

In external validation, bias (difference between mCl and eCl) was within ± 1.0 unit for all equations. Accuracy (percent of differences within ± 2.0 units) was significantly better for eClBTP, eClB2M, and eClBTP-B2M than eClUN-cr for both mClUN (78%, 80%, and 81% vs 72%; P < 0.05 for all) and mClUN-cr (72%, 78%, and 79% vs 68%; P < 0.05 for all). The area under the curve for predicting mClUN > 2.0 mL/min was highest for eClB2M (0.853) and eClBTP-B2M (0.848). Results were similar for other validated equations.

LIMITATIONS

Development cohort only consisted of PD patients, no gold-standard method for residual kidney function measurement.

CONCLUSIONS

These results confirm the validity and extend the generalizability of residual kidney function estimating equations from serum concentrations of low-molecular-weight proteins without urine collection.

Center-Specific Risk-Adjusted Standardized Mortality Rates on Continuous Ambulatory Peritoneal Dialysis in China

Background

The aim of this study was to determine if there were centers in China with unusually high levels of risk-adjusted mortality in continuous ambulatory peritoneal dialysis (CAPD) patients.

Methods

We analyzed an inception cohort commencing CAPD between 1 January 2005 and 13 August 2015, followed until death, dropout defined as discontinuation of Baxter products, loss to follow-up, or 13 November 2015, whichever occurred first. We calculated standardized mortality ratios (SMRs) from Cox proportional hazards models, adjusting for age, gender, employment status, insurance status, primary renal disease, size of peritoneal dialysis (PD) program, and year of dialysis inception. We calculated 2 SMRs, 1 from models including a fixed effect for center of treatment, and 1 from stratified models.

Results

In this study, there was a 9.9% annual mortality rate in China, with decreasing mortality risk over time. There was significant variation of outcomes between Chinese centers, with up to 20% of facilities having SMRs indicating a higher risk-adjusted mortality rate than average. In particular, larger centers had better than expected mortality than smaller ones. There was significant misclassification of SMRs calculated using stratification versus fixed-effects models, although both showed directionally similar results.

Conclusion

Despite overall satisfactory and improving outcomes, our study showed a significant proportion of PD centers with higher than expected mortality. This is a signal for further assessment of these centers in China, after which there might be a range of actions taken depending on the results of the assessment and context, bearing in mind that the variation seen may be driven by factors unrelated to quality of care or beyond the control of hospital.

Safety and effectiveness evaluation of a domestic peritoneal dialysis fluid packed in non-PVC bags: study protocol for a randomized controlled trial

BACKGROUND

Peritoneal dialysis is an important type of renal replacement therapy for uremic patients. In peritoneal dialysis, fluids fill in and flow out of the abdominal cavity three to five times per day. Usually, the fluid is packed in a polyvinyl chloride (PVC) bag. Safety concerns have arisen over di-(2-ethylhexyl) phthalate, which is essential in the formation of PVC materials. In 2011, the National Development and Reform Commission of China released a catalog of industrial structural adjustments, mandating the elimination of PVC bags for intravenous infusion and food containers. Although bags for peritoneal dialysis fluid were not included in the elimination list, several manufacturers began to develop new materials for fluid bags. HUAREN peritoneal dialysis fluid consists of the same electrolytes and buffer agent as in Baxter fluid, but is packed in bags that do not contain PVC. This multicenter randomized controlled trial was designed to compare peritoneal dialysis fluid packed in non-PVC-containing and PVC-containing bags. Further, the study sought to determine the proper dose of peritoneal dialysis fluid and the actual survival rates of Chinese patients undergoing peritoneal dialysis.

METHODS/DESIGN

The study participants are adults undergoing continuous ambulatory peritoneal dialysis for 30 days to 6 months. All eligible patients are randomized (1:1) to peritoneal dialysis with Baxter and HUAREN dialysis fluids (initial dose, 6 l/day), with dosages adjusted according to a unified protocol. The primary outcomes are the 1-, 2-, 3-, 4-, and 5-year overall survival rates. Secondary outcome measures include technique survival rates, reductions in estimated glomerular filtration rate, nutritional status, quality of life, cardiovascular events, medical costs and drop-out rates. Safety outcome measures include adverse events, changes in vital signs and laboratory parameters, peritonitis, allergies, and quality of products.

DISCUSSION

This study is the first to evaluate the long-term safety and effectiveness of a non-PVC packed peritoneal dialysis fluid. The effects of plasticizer on patient long-term survival will be determined. The characteristics of Chinese patients undergoing peritoneal dialysis will be determined, including proper dose, technique survival rates, patient survival rates, and medical costs.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01779557 .