Changes in erythropoiesis-stimulating agent responsiveness after transfer to combined therapy with peritoneal dialysis and hemodialysis for patients on peritoneal dialysis: A prospective multicenter study in Japan

INTRODUCTION

Inadequate dialysis and fluid overload are corrected after starting combined therapy with peritoneal dialysis (PD) and hemodialysis (HD). However, the effects on anemia management has not been elucidated.

METHODS

We conducted a prospective, multicenter, observational cohort study of 40 PD patients (age, 60 ± 10 years; male, 88%; median PD duration, 28 months) starting combined therapy and investigated changes in several clinical parameters, including erythropoiesis-stimulating agent (ESA) resistance index (ERI).

RESULTS

ERI decreased significantly during 6 months after switching to combined therapy (from 11.8 [IQR 8.0-20.4] units/week/kg/(g/dL) to 7.8 [IQR 3.9-18.6] units/week/kg/(g/dL), p = 0.047). Body weight, urinary volume, serum creatinine and the dialysate-to-plasma creatinine ratio (D/P Cr) decreased, whereas hemoglobin and serum albumin increased. In subgroup analysis, the changes in ERI were not affected by cause for starting combined therapy, PD holiday and D/P Cr.

CONCLUSION

Although detailed mechanism was unclear, ESA responsiveness improved after switching from PD alone to combined therapy.

Utility of serum beta-trace protein as a tool for estimating residual kidney function in peritoneal dialysis patients

BACKGROUND

Beta-trace protein (BTP) is a novel marker for residual kidney function (RKF) without need for urinary collection. We aimed to examine its utility as a tool for estimating RKF in incident peritoneal dialysis (PD) patients.

METHODS

This was a post hoc analysis of incident PD patients from the balANZ trial cohort. The outcomes evaluated were trends of serum BTP concentration with time, factors associated with change in BTP using mixed-effect multilevel linear regression and correlation of BTP with mean urinary urea and creatinine clearances (measured glomerular filtration rate (GFR)). Performances of two BTP-derived equations (Shafi-Eqn and Steubl-Eqn) to estimate GFR were evaluated by reporting bias (median difference between estimated and measured GFR), precision (interquartile range of median bias), accuracy (±2 mL/min of measured GFR) and P30 (percentage estimates within 30% of measured GFR) with confidence intervals (CIs) generated by bootstrapping 2000 replicates. The agreement between BTP-estimated GFR and measured GFR was also plotted graphically on Bland-Altman analysis.

RESULTS

The study included 161 PD patients. BTP concentration increased with dialysis vintage and was inversely correlated with measured GFR (r = -0.64). Larger increases in BTP were associated with longer PD vintage and higher dialysate glucose exposure. Biases of BTP-estimated GFRs (Shafi-Eqn and Steubl-Eqn) were 1.2 mL/min/1.73 m² (95% CI 1.0-1.3 mL/min/1.73 m²) and 0.4 mL/min/1.73 m² (95% CI 0.2-0.6 mL/min/1.73 m²), respectively. Both BTP-estimated GFRs had poor precision (3.2 mL/min/1.73 m² (95% CI 2.9-3.5 mL/min/1.73 m²) and 2.8 mL/min/1.73 m² (95% CI 2.5-3.2 mL/min/1.73 m²), respectively) and accuracy of estimates (55% (95% CI 52-60%) and 59% (95% CI 55-63%), respectively). The mean difference of BTP-estimated GFR (Shafi-Eqn and Steubl-Eqn) and measured GFR were -1.14 mL/min/1.73 m² and -0.42 mL/min/1.73 m², respectively, with large limit of agreement on Bland-Altman plot.

CONCLUSIONS

Serum BTP level was inversely related to RKF but neither BTP-estimated GFR equations were sufficiently accurate for routine use in PD patients.

Hospitalization for Patients on Combination Therapy With Peritoneal Dialysis and Hemodialysis Compared With Hemodialysis

Introduction

Combination therapy with peritoneal dialysis and hemodialysis (PD+HD) is widely used for PD patients with decreased residual kidney function in Japan; however, hospitalization for this combined dialysis has not been investigated so far. We compared the risk of hospitalization for PD+HD with that for HD.

Methods

A multicenter, prospective observational study was conducted on 42 PD+HD and 42 HD patients matched for age and diabetic nephropathy. The main outcome measure was the cumulative incidence of hospitalization for any cause assessed with the Kaplan-Meier method. Hospitalization rates (the number of admissions per 100 patient-years) associated with dialysis modality were also calculated. The impact of dialysis modality on time to hospitalization was analyzed using the Cox proportional hazard model.

Results

There was no significant difference between groups in terms of age, sex, dialysis vintage, diabetic nephropathy, and comorbidities. The cumulative incidence of hospitalization did not significantly differ between the groups (log-rank test, P = 0.36). Although total hospitalization rates were 66.0 in PD+HD and 59.2 in HD, hospitalization rates for the sum of PD-related infections (a composite of catheter-related infection and peritonitis) and vascular access troubles were 21.7 in PD+HD and 7.2 in HD. On univariate Cox proportional hazard analysis, dialysis modality had no significant impact on time to hospitalization.

Conclusion

The risk of hospitalization was not significantly different between PD+HD and HD, although PD+HD patients had a higher risk of dialysis access–related complications than HD patients.

Ultrafiltration Rate, Residual Kidney Function, and Survival Among Patients Treated With Reduced-Frequency Hemodialysis

RATIONALE & OBJECTIVE

Patients receiving twice-weekly or less-frequent hemodialysis (HD) may need to undergo higher ultrafiltration rates (UFRs) to maintain acceptable fluid balance. We hypothesized that higher UFRs are associated with faster decline in residual kidney function (RKF) and a higher rate of mortality.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

1,524 patients with kidney failure who initiated maintenance HD at a frequency of twice or less per week for at least 6 consecutive weeks at some time between 2007 and 2011 and for whom baseline data for UFR and renal urea clearance were available.

PREDICTOR

Average UFR during the first patient-quarter during less-frequent HD (<6, 6-<10, 10-<13, and≥13mL/h/kg).

OUTCOME

Time to all-cause and cardiovascular death, slope of decline in RKF during the first year after initiation of less-frequent HD (with slopes above the median categorized as rapid decline).

ANALYTICAL APPROACH

Cox proportional hazards regression for time to death and logistic regression for the analysis of rapid decline in RKF.

RESULTS

Among 1,524 patients, higher UFR was associated with higher all-cause mortality; HRs were 1.43 (95% CI, 1.09-1.88), 1.51 (95% CI, 1.08-2.10), and 1.76 (95% CI, 1.23-2.53) for UFR of 6 to<10, 10 to<13, and≥13mL/h/kg, respectively (reference: UFR < 6mL/h/kg). Higher UFR was also associated with higher cardiovascular mortality. Baseline RKF modified the association between UFR and mortality; the association was attenuated among patients with renal urea clearance≥5mL/min/1.73m². Higher UFR had a graded association with rapid decline in RKF; ORs were 1.73 (95% CI, 1.18-2.55), 1.89 (95% CI, 1.12-3.17), and 2.75 (95% CI, 1.46-5.18) at UFRs of 6 to<10, 10 to<13, and≥13mL/h/kg, respectively (reference: UFR < 6mL/h/kg).

LIMITATIONS

Residual confounding from unobserved differences across exposure categories.

CONCLUSIONS

Higher UFR was associated with worse outcomes, including shorter survival and more rapid loss of RKF, among patients receiving regular HD treatments at a frequency of twice or less per week.

Impact of Obesity on Modality Longevity, Residual Kidney Function, Peritonitis, and Survival Among Incident Peritoneal Dialysis Patients

BACKGROUND

The prevalence of severe obesity, often considered a contraindication to peritoneal dialysis (PD), has increased over time. However, mortality has decreased more rapidly in the PD population than the hemodialysis (HD) population in the United States. The association between obesity and clinical outcomes among patients with end-stage kidney disease remains unclear in the current era.

STUDY DESIGN

Historical cohort study.

SETTING & PARTICIPANTS

15,573 incident PD patients from a large US dialysis organization (2007-2011).

PREDICTOR

Body mass index (BMI).

OUTCOMES

Modality longevity, residual renal creatinine clearance, peritonitis, and survival.

RESULTS

Higher BMI was significantly associated with shorter time to transfer to HD therapy (P for trend < 0.001), longer time to kidney transplantation (P for trend < 0.001), and, with borderline significance, more frequent peritonitis-related hospitalization (P for trend = 0.05). Compared with lean patients, obese patients had faster declines in residual kidney function (P for trend < 0.001) and consistently achieved lower total Kt/V over time (P for trend < 0.001) despite greater increases in dialysis Kt/V (P for trend < 0.001). There was a U-shaped association between BMI and mortality, with the greatest survival associated with the BMI range of 30 to < 35kg/m2 in the case-mix adjusted model. Compared with matched HD patients, PD patients had lower mortality in the BMI categories of < 25 and 25 to < 35kg/m2 and had equivalent survival in the BMI category ≥ 35kg/m2 (P for interaction = 0.001 [vs < 25 kg/m2]). This attenuation in survival difference among patients with severe obesity was observed only in patients with diabetes, but not those without diabetes.

LIMITATIONS

Inability to evaluate causal associations. Potential indication bias.

CONCLUSIONS

Whereas obese PD patients had higher risk for complications than nonobese PD patients, their survival was no worse than matched HD patients.

Incremental Hemodialysis, Residual Kidney Function, and Mortality Risk in Incident Dialysis Patients: A Cohort Study

BACKGROUND

Maintenance hemodialysis is typically prescribed thrice weekly irrespective of a patient's residual kidney function (RKF). We hypothesized that a less frequent schedule at hemodialysis therapy initiation is associated with greater preservation of RKF without compromising survival among patients with substantial RKF.

STUDY DESIGN

A longitudinal cohort.

SETTING & PARTICIPANTS

23,645 patients who initiated maintenance hemodialysis therapy in a large dialysis organization in the United States (January 2007 to December 2010), had available RKF data during the first 91 days (or quarter) of dialysis, and survived the first year.

PREDICTOR

Incremental (routine twice weekly for >6 continuous weeks during the first 91 days upon transition to dialysis) versus conventional (thrice weekly) hemodialysis regimens during the same time.

OUTCOMES

Changes in renal urea clearance and urine volume during 1 year after the first quarter and survival after the first year.

RESULTS

Among 23,645 included patients, 51% had substantial renal urea clearance (≥3.0mL/min/1.73m(2)) at baseline. Compared with 8,068 patients with conventional hemodialysis regimens matched based on baseline renal urea clearance, urine volume, age, sex, diabetes, and central venous catheter use, 351 patients with incremental regimens exhibited 16% (95% CI, 5%-28%) and 15% (95% CI, 2%-30%) more preserved renal urea clearance and urine volume at the second quarter, respectively, which persisted across the following quarters. Incremental regimens showed higher mortality risk in patients with inadequate baseline renal urea clearance (≤3.0mL/min/1.73m(2); HR, 1.61; 95% CI, 1.07-2.44), but not in those with higher baseline renal urea clearance (HR, 0.99; 95% CI, 0.76-1.28). Results were similar in a subgroup defined by baseline urine volume of 600mL/d.

LIMITATIONS

Potential selection bias and wide CIs.

CONCLUSIONS

Among incident hemodialysis patients with substantial RKF, incremental hemodialysis may be a safe treatment regimen and is associated with greater preservation of RKF, whereas higher mortality is observed after the first year of dialysis in those with the lowest RKF. Clinical trials are needed to examine the safety and effectiveness of twice-weekly hemodialysis.