Vickie Wai-Ki Kwong

BIOIMPEDANCE SPECTROSCOPY FOR THE DETECTION OF FLUID OVERLOAD IN CHINESE PERITONEAL DIALYSIS PATIENTS

♦ Background: Fluid overload probably contributes to the cardiovascular risk of peritoneal dialysis (PD) patients. We studied the relationship between over-hydration as determined by bioimpedance spectroscopy and dialysis adequacy, nutritional status, and arterial stiffness in Chinese PD patients. ♦ Methods: We studied 122 asymptomatic prevalent PD patients: bioimpedance spectroscopy, arterial pulse wave velocity, dialysis adequacy and nutritional status were determined. ♦ Results: Of the 122 patients, 88 (72.1%) had over-hydration of ≥ 1 L, while 25 (20.5%) were ≥ 5 L. Over-hydration significantly correlated with total body water (r = 0.474, p < 0.001) and extracellular water (r = 0.755, p < 0.001). Over-hydration was more severe in male and diabetic patients, and significantly correlated with Charlson’s comorbidity score, blood pressure, body mass index, body weight, peritoneal transport characteristics, and carotid-femoral pulse wave velocity. Over-hydration significantly correlated with Kt/V (r = -0.287, p = 0.016), serum albumin level (r = -0.465, p < 0.001) and malnutrition inflammation score (r = 0.410, p = 0.006), but not residual renal function. ♦ Conclusion: Over-hydration is common in asymptomatic Chinese PD patients. The degree of over-hydration is particularly pronounced in patients who are inadequately dialyzed, have multiple comorbid conditions and low serum albumin levels. Over-hydration is associated with high blood pressure and arterial stiffness, and may contribute to the excessive risk of cardiovascular disease in this group of patients.

Long-term Outcome of Biopsy-Proven Minimal Change Nephropathy in Chinese Adults

BACKGROUND Minimal change nephropathy is a common cause of primary nephrotic syndrome in adults. However, there are few studies of its clinical course, response to treatment, and long-term outcome. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS 340 consecutive adult patients with nephrotic syndrome and biopsy-proven minimal change nephropathy treated in a university hospital from 1984 until 2004. FACTORS Treatment response groups: primary steroid resistance, frequent relapse (≥4 relapses within 1 year), infrequent relapse (≥1 relapse but not frequent relapse), and no relapse (reference group); disease pattern. OUTCOME Medical problems after diagnosis; patient survival; renal survival. RESULTS Median time to remission was 10 (IQR, 8-12) weeks; 179 (52.6%) had no relapse, 42 (12.4%) had infrequent relapses, 86 (25.3%) were frequent relapsers or steroid dependent, and 33 (9.7%) had primary steroid resistance. After a median follow-up of 174.7 (IQR, 119.7-235.0) months, 32 patients developed end-stage renal disease and 62 died (25 after progression to end-stage renal disease). Cox regression analysis showed that age and treatment response groups were the independent predictors of patient survival. Compared to the no-relapse group, the infrequent-relapse group had significantly better patient survival (adjusted HR, 0.19; 95% CI, 0.08-0.44; P<0.001), whereas the primary-steroid-resistance group had significantly worse patient survival (adjusted HR, 5.87; 95% CI, 1.83-18.85; P<0.001). Renal survival was excellent except in the primary-steroid-resistance group. LIMITATIONS Retrospective study. CONCLUSIONS A substantial proportion of adult patients with minimal change nephropathy continue to have disease flares more than 10 years after the initial presentation, and medical problems after diagnosis are common.

PERSISTENT SYMPTOMATIC INTRA-ABDOMINAL COLLECTION AFTER CATHETER REMOVAL FOR PD-RELATED PERITONITIS

♦ Background: Peritoneal dialysis (PD) patients with severe peritonitis require catheter removal. It is often assumed that this approach, together with antibiotics, would eradicate the infection; however, some patients continue to have problems despite catheter removal. ♦ Method: We reviewed 30 consecutive PD patients in our center from 1997 to 2008 with recurrent loculated peritoneal collection after catheter removal for severe peritonitis. ♦ Results: Of the 1928 episodes of peritonitis that occurred in 702 patients during the study period, 11.1% required catheter removal and 1.6% developed recurrent peritoneal collection that required percutaneous drainage. Median time to diagnosis of intra-abdominal collection was 12 days after catheter removal (interquartile range 7 – 61 days). In 25 patients (83.3%), aspirate of the abdominal collection was culture negative. In 17 patients (56.7%), the abdominal collection was recurrent and required repeated percutaneous aspiration. Only 3 patients had successful reinsertion of the peritoneal catheter but all had reduced small solute clearance after returning to PD. ♦ Conclusion: A small but not negligible proportion of patients with PD-related peritonitis develop recurrent intra-abdominal collection that requires percutaneous drainage after catheter removal. The chance of a successful return to PD is very low in this group of patients. Direct conversion to long-term hemodialysis may avoid unnecessary attempts at peritoneal catheter reinsertion.

Outcome of Hemodialysis Patients Who Had Failed Peritoneal Dialysis

Background: Peritoneal dialysis (PD) and hemodialysis (HD) are often regarded as equivalent choices of renal replacement therapy. However, little is known about the outcome of patients who failed PD and converted to long-term HD. Methods: We reviewed 197 patients who received long-term HD after failed PD in a University hospital from 1994 to 2008 (the PD-first group) and 140 patients who received long-term HD as their initial therapy during that period (the primary-HD group). Their survival rates are compared. Results: The two groups are highly comparable in terms of baseline demographic data. The PD-first group required more temporary dialysis catheters than the primary-HD group (3.1 ± 3.4 vs. 1.5 ± 1.8, p < 0.0001). At 5 years, the actuarial survival of the PD-first group was significantly lower than that of the primary-HD group (39.9 vs. 59.7%, p < 0.0001), while technique survival was similar (30.4 vs. 30.1%, p = 0.7). When analysis on actuarial survival was performed for patients who survived the first 12 months on HD, the 5-year survival became similar (65.2 vs. 68.8%, p = 0.5). During the first 12 months on HD, independent predictors of actuarial survival of the PD-first group were duration of PD, Charlson’s comorbidity score, type of permanent access and serum albumin before conversion; after 12 months, independent predictors of actuarial survival were Charlson’s comorbidity score, total Kt/V, residual renal function, fat-free edema-free body mass before conversion and baseline peritoneal transport. Conclusion: Patients who were converted to long-term HD after failed PD had a higher mortality than patients who used HD as the primary modality of renal replacement therapy. The excessive mortality, however, was limited to the first 12 months after conversion, and the technique survival was similar between the two groups. Vascular access is a common problem in patients who failed PD.

The Effect of Neutral Peritoneal Dialysis Solution with Low Glucose-Degradation-Product on the Fluid Status and Body Composition--A Randomized Control Trial.

Background Previous studies report conflicting results on the benefit of peritoneal dialysis (PD) patients treated with low glucose degradation product (GDP) solution. The effects of low GDP solution on body fluid status and arterial pulse wave velocity (PWV) have not been studied. Methods We randomly assigned 68 incident PD patients to low GDP (Intervention Group) or conventional solutions (Control Group); 4 dropped off before they received the assigned treatment. Patients were followed for 52 weeks for changes in ultrafiltration, residual renal function, body fluid status and arterial PWV. Result After 52 weeks, Intervention Group had higher overhydration (3.1 ± 2.6 vs 1.9 ± 2.2 L, p = 0.045) and extracellular water volume (17.7 ± 3.9 vs 15.8 ± 3.1 L, p = 0.034) than Control Group. There was no significant difference in PWV between groups. There was no significant difference in residual renal function between the Groups. Intervention Group had lower ultrafiltration volume than Control Group at 4 weeks (0.45 ± .0.61 vs 0.90 ± 0.79 L/day, p = 0.013), but the difference became insignificant at later time points. Intervention Group had lower serum CRP levels than Control Group (4.17 ± 0.77 vs 4.91 ± 0.95 mg/dL, p < 0.0001). Conclusion Incident PD patients treated with low GDP solution have less severe systemic inflammation but trends of less ultrafiltration, and more fluid accumulation. However, the effects on ultrafiltration and fluid accumulation disappear with time. The long term effect of low GDP solution requires further study. Trial Registration ClinicalTrials.gov NCT00966615

Life expectancy of Chinese patients with chronic kidney disease without dialysis.

Aim:  Long term dialysis is life‐saving for patients with end stage renal disease (ESRD). However, in ESRD patients with multiple comorbid conditions, dialysis may actually be futile, and conservative management is advisable. We studied the life expectancy of Chinese ESRD patients treated conservatively.

Current Challenges and Opportunities in PD

Despite the gradual increased use of peritoneal dialysis (PD) globally around the world, it is recognized that a number of areas in PD as a renal-replacement therapy require attention and improvements. The current challenges in PD include how to tackle technique failure and sustain long-term PD, manage and prevent peritoneal infections, malnutrition and inflammation, cardiovascular mortality, volume overload, glucose exposure, adequacy of solute removal, peritoneal access, peritoneal physiology and changes with long-term PD, patient fatigue, psychosocial issues, and care of elderly patients on PD. Obviously, hemodialysis as another renal-replacement therapy modality also has its own areas that need attention and improvement by nephrologists and nurses. With more clinical and basic science research, outcome studies, and through better education and training, together with the implementation of global PD guidelines for enhancing care of PD patients, it is likely that such problem areas in PD gradually will be resolved and PD patient outcomes will be improved.

Plasma Mitochondrial DNA Level is a Prognostic Marker in Peritoneal Dialysis Patients.

Background/Aims: Circulating bacterial DNA fragment is related to systemic inflammatory state in peritoneal dialysis (PD) patients. We hypothesize that circulating mitochondrial DNA, which has a similar structure with bacterial DNA, correlates with systemic inflammatory state and predicts cardiovascular event in new PD patients. Methods: We measured plasma mitochondrial DNA level by quantitative polymerase chain reaction (PCR) in 197 new PD patients and 150 patients with chronic kidney disease. PD patients were followed for 24 months for the development of cardiovascular event, hospitalization, and patient survival. Results: There was a stepwise increase in plasma mitochondrial DNA level with worsening renal function. The average plasma mitochondrial DNA level was 18.0 ± 1.2 PCR cycles. Plasma mitochondrial DNA level correlated with serum CRP level (r = -0.538, p < 0.0001). At 24 months, the event-free survival was 67.4%, 66.4%, 63.4% and 44.2% for plasma mitochondrial DNA level quartiles I, II, III and IV, respectively (p = 0.049). After adjusting for confounders, plasma mitochondrial DNA level, malnutrition-inflammation score, and baseline arterial pulse wave velocity were independent predictors of composite cardiovascular end-point; each doubling in plasma mitochondrial DNA level confers 16.0% (95% confidence interval, 2.5 - 31.3%, p = 0.001) excess in risk. Plasma mitochondrial DNA also correlated with the number of hospital admission (r = -0.218, p = 0.002) and duration of hospitalization for cardiovascular reasons (r = -0.232, p = 0.001). Conclusion: Plasma mitochondrial DNA level significantly correlates with systemic inflammatory state, and is a strong predictor of cardiovascular event as well as the need of hospitalization in new PD patients.

Peritoneal Dialysis Catheter Revision and Replacement by Nephrologist for Peritoneal Dialysis Catheter Malfunction

Background: Catheter malfunction is an important cause of technique failure for peritoneal dialysis (PD) patients, and is commonly managed by surgeons or intervention radiologists. We reviewed our experience in catheter revision or replacement by nephrologists. Method: We reviewed the clinical outcome and complication rate of 95 consecutive patients who had PD catheter malfunction, with catheter revision or replacement by nephrologist. Result: Amongst the 95 patients, 32 had catheter revision, 24 catheter replacement via the original wound, and 39 catheter replacement via a new mini-laparotomy wound. Catheter survival was 71.6% at 1 month and 48.4% at 6 months; technique survival was 88.4% at 1 month and 77.4% at 6 months. When the 3 types of procedure were analyzed separately, technique survival at 1 month was 96.8, 75.0, and 89.7%, respectively, for patients who received catheter revision, catheter replacement via the original wound, and catheter replacement via a new mini-laparotomy wound (p = 0.0002), although their catheter survival rates were not significantly different. Also, 2 patients had bleeding that required urgent surgical exploration, 2 had wound infection, and 8 had peritonitis within 4 weeks after the surgery. Conclusion: PD catheter revision and replacement by nephrologist has an acceptable catheter survival and a reasonable complication rate. Given that prompt intervention is an important consideration, catheter revision and replacement by nephrologist is a suitable method for the management of catheter malfunction.

Depression and Physical Frailty Have Additive Effect on the Nutritional Status and Clinical Outcome of Chinese Peritoneal Dialysis

Background/Aims: Frailty and depression both contribute to malnutrition and adverse clinical outcome of peritoneal dialysis (PD) patients. However, their interaction is incompletely defined. Methods: We studied 178 adult Chinese PD patients. Physical frailty was assessed by a validated in-house questionnaire; depressive symptoms was screened by the Geriatric Depression Scale; nutritional status was determined by subjective global assessment (SGA) and malnutrition inflammation score (MIS). All patients were followed for up to 24 months for survival and hospitalization analysis. Results: There were 111 patients (62.4%) physically frail, amongst those 48 (43.2%) had depressive symptoms. Only 1 patient had depressive symptoms without frailty. There was an additive effect of depressive symptoms and physical frailty on nutritional status. For the groups with no frailty, frail but no depressive symptoms, and frail with depressive symptoms, serum albumin decreased in a stepwise manner (35.8 ± 5.6, 34.9 ± 4.4, and 32.9 ± 5.3 g/L, respectively, p=0.025); overall SGA score was 5.75 ± 0.61, 5.41 ± 0.59, and 5.04 ± 0.77, respectively (p< 0.0001), and MIS was 5.12 ± 2.30, 7.13 ± 3.22, and 9.48 ± 3.97, respectively (p< 0.0001). At 24 months, patient survival was 86.6%, 71.4%, and 62.5% for patients with no frailty, frail but no depressive symptoms, and frail with depressive symptoms, respective (p=0.001). The median number of hospital stay was 8.04 (inter-quartile range [IQR] 0.91 – 19.42), 14.05 (IQR 3.57 – 37.27), and 26.62 (IQR 10.65 – 61.18) days per year of follow up, respectively (p< 0.0001). Conclusion: Physical frailty and depressive symptoms are both common in Chinese PD patients, and they have additive adverse effect on the nutritional status and clinical outcome.