Man-Ching Law

Independent effects of residual renal function and dialysis adequacy on nutritional status and patient outcome in continuous ambulatory peritoneal dialysis

Dialysis adequacy has a major impact on outcome of continuous ambulatory peritoneal dialysis (CAPD) patients. However, there is a substantial confounding effect by residual renal function in most studies. We differentiated the effects of dialysis adequacy from those of residual renal function on nutritional status and outcome of CAPD patients. We identified 168 CAPD patients treated in our center between September 1995 and December 1996 and categorized them into three groups: 49 patients with an average total Kt/V of 1.93 +/- 0.18 and a median residual glomerular filtration rate (GFR) of 0. 07 mL/min/1.73 m(2) in the dialysis-dependent (DD) group; 48 patients with an average total Kt/V of 2.03 +/- 0.25 and a residual GFR of 2. 33 mL/min/1.73 m(2) in the residual renal function (RRF) group; and 71 patients with an average total Kt/V of 1.38 +/- 0.22 and a residual GFR of 0.05 mL/min/1.73 m(2) in the control (CTL) group. They were followed-up for 1 year to compare baseline nutritional status and 1-year morbidity. Baseline normalized protein catabolic rates (NPCR) are 1.00 +/- 0.20 and 0.96 +/- 0.19 (for RRF and DD, respectively) versus 0.89 +/- 0.16 g/kg/d for CTL (P < 0.01). Percentage lean body mass (%LBM) was 71.6 +/- 9.8 and 71.5 +/- 10.0 (for RRF and DD, respectively) versus 65.2 +/- 8.5% for CTL (P < 0. 001). No difference was seen in the nutritional status between RRF and DD groups. Duration of hospitalization for 1 year was 6.9 +/- 11. 8 days in the RRF group versus 14.9 +/- 25.1 in the DD and 10.6 +/- 11.6 days in the CTL groups (P < 0.05). The peritonitis rate was 44. 4 patient-months for the RRF group, versus 13.6 for the DD and 12.9 for the CTL groups (P < 0.05). There also was a trend toward superior 1-year technique survival in the RRF group, but the number of observations was small. There was no difference in duration of hospitalization, peritonitis rate, and technique survival between the DD and CTL groups. Short-term morbidity in patients without residual renal function appears to be independent of total Kt/V, although Kt/V may have some effects on nutritional status. The assumption that renal and peritoneal clearances are equivalent must be carefully reexamined. Further studies on the effect of dialysis adequacy in patients without residual renal function are urgently needed.

Staphylococcus aureus Peritonitis Complicates Peritoneal Dialysis: Review of 245 Consecutive Cases

Peritonitis that is caused by Staphylococcus aureus is a serious complication in peritoneal dialysis (PD), but the clinical course of PD-related S. aureus peritonitis remains unclear. All of the S. aureus peritonitis in a dialysis unit from 1994 to 2005 were reviewed. During this period, 2065 episodes of peritonitis were recorded; 245 (11.9%) episodes in 152 patients were caused by S. aureus and 45 (18.4%) episodes were caused by methicillin-resistant S. aureus (MRSA). Patients with a history of recent hospitalization had a higher risk for isolation of MRSA than the others (30.6 versus 14.2%; P = 0.004). The overall primary response rate was 87.8%; the complete cure rate was 74.3%. However, 21 (8.6%) episodes developed relapse and 59 (24.1%) developed repeat S. aureus peritonitis. Episodes that were caused by MRSA had a lower primary response rate (64.4 versus 93.0%; P < 0.001) and complete cure rate (60.0 versus 77.5%; P = 0.023) than the others. Episodes that were treated initially with vancomycin had better primary response rate than those that were treated with cefazolin (98.0 versus 85.2%; P = 0.001), but the complete cure rate was similar. Adjuvant rifampicin treatment was associated with a significantly lower risk for relapse or repeat S. aureus peritonitis than was treatment without rifampicin (21.4 versus 42.8%; P = 0.004). In contrast, initial antibiotic regimen (cefazolin versus vancomycin) and concomitant exit-site infection did not have any effect on the risk for relapse or repeat peritonitis. S. aureus peritonitis is a serious complication of PD. Recent hospitalization is a major risk factor of methicillin resistance in the bacterial isolate. Rifampicin is a valuable adjunct in preventing relapse and repeat S. aureus peritonitis after the index episode.

Change in bacterial aetiology of peritoneal dialysis-related peritonitis over 10 years: experience from a centre in south-east Asia

n ABSTRACTn n This study reviewed 1787 episodes of peritoneal dialysis (PD)-related peritonitis in 544 patients between 1994 and 2003. The overall rate of peritonitis was 0.68 episodes/year of PD, but decreased from 1.10 to 0.46 episodes/year between 1994 and 2003. The incidence of peritonitis caused by coagulase-negative staphylococci declined between 1994 and 1998 from 0.21 to 0.06 episodes/year of PD, coinciding with a reduction in the use of spike PD sets. There was a 60.1% response rate to antibiotics throughout the period, but the percentage of cases that required modification of the initial empirical antibiotic regimen rose from 13.6% to 58.7%, indicating that treatment should be individualised.n n

Coagulase Negative Staphylococcal Peritonitis in Peritoneal Dialysis Patients: Review of 232 Consecutive Cases

BACKGROUND AND OBJECTIVESnCoagulase-negative Staphylococcus species is the most common cause of peritoneal dialysis-related peritonitis; however, the optimal treatment strategy of coagulase-negative Staphylococcus species peritonitis remains controversial.nnnDESIGN, SETTING, PARTICIPANTS, & MEASUREMENTSnAll of the coagulase-negative Staphylococcus species peritonitis in a dialysis unit from 1995 to 2006 were reviewed. During this period, there were 2037 episodes of peritonitis recorded; 232 episodes (11.4%) in 155 patients were caused by coagulase-negative Staphylococcus species.nnnRESULTSnThe overall primary response rate was 95.3%; the complete cure rate was 71.1%. Patients with a history of recent hospitalization or recent antibiotic therapy had a higher risk for developing methicillin-resistant strains. Episodes that were treated initially with cefazolin or vancomycin had similar primary response rate and complete cure rate. There were 33 (14.2%) episodes of relapse and 29 (12.5%) episodes of repeat peritonitis; 12 (60.6%) of the repeat episodes developed within 3 mo after completion of antibiotics. Relapse or repeat episodes had a significantly lower complete cure rate than the other episodes. For relapse or repeat episodes, treatment with effective antibiotics for 3 wk was associated with a significantly higher complete cure rate than the conventional 2-wk treatment.nnnCONCLUSIONSnCoagulase-negative Staphylococcus species peritonitis remains a common complication of peritoneal dialysis. Methicillin resistance is common, but the treatment outcome remains favorable when cefazolin is used as the first-line antibiotic. A 3-wk course of antibiotic can probably achieve a higher cure rate in relapse or repeat episodes.

Recurrent and relapsing peritonitis: causative organisms and response to treatment.

BACKGROUNDnThe clinical behavior and optimal treatment of relapsing and recurrent peritonitis episodes in patients undergoing long-term peritoneal dialysis are poorly understood.nnnSTUDY DESIGNnRetrospective study over 14 years.nnnSETTING & PARTICIPANTSnUniversity dialysis unit; 157 relapsing episodes (same organism or culture-negative episode occurring within 4 weeks of completion of therapy for a prior episode), 125 recurrent episodes (different organism, occurs within 4 weeks of completion of therapy for a prior episode), and 764 control episodes (first peritonitis episode without relapse or recurrence).nnnPREDICTORSnExit-site infection, empirical antibiotics.nnnOUTCOME MEASURESnPrimary response (resolution of abdominal pain, clearing of dialysate, and peritoneal dialysis effluent neutrophil count < 100 cells/mL after 10 days of antibiotic therapy), complete cure (resolution by using antibiotics without relapse/recurrence), catheter removal (for any cause while on antibiotic therapy), and mortality.nnnRESULTSnCompared with the control group, more relapsing episodes were caused by Pseudomonas species (16.6% versus 9.4%) and were culture negative (29.9% versus 16.4%); recurrent infections commonly were caused by Enterococcus species (3.2% versus 1.2%) or other Gram-negative organisms (27.2% versus 11.1%) or had mixed bacterial growth (17.6% versus 12.7%). There were significant differences in primary response, complete cure, and mortality rates among groups (P < 0.001 for all comparisons). Compared with the control and relapsing groups, post hoc analysis showed that the recurrent group had a significantly lower primary response rate (86.4%, 88.5%, and 71.2%, respectively), lower complete cure rate (72.3%, 62.4%, and 42.4%, respectively), and higher mortality rate (7.7%, 7.0%, and 20.8%, respectively).nnnLIMITATIONSnRetrospective analysis.nnnCONCLUSIONnRelapsing and recurrent peritonitis episodes are caused by different spectra of bacteria and probably represent 2 distinct clinical entities. Recurrent peritonitis episodes had a worse prognosis than relapsing ones.

Geriatric Nutritional Risk Index as a Screening Tool for Malnutrition in Patients on Chronic Peritoneal Dialysis

BACKGROUNDnMalnutrition is common among peritoneal dialysis (PD) patients. Recently, the Geriatric Nutrition Risk Index (GNRI) was found to be a reliable tool for screening malnutrition in hemodialysis patients. However, the GNRI has not been validated in PD patients.nnnMETHODSnWe studied 314 unselected, adult PD patients from a single dialysis unit. We compared their GNRI scores with their comprehensive Malnutrition-Inflammation Scores (MIS) and 7-point Subjective Global Assessment (SGA) scores. We randomly selected 106 patients for a repeated assessment, and the changes in their three indices were compared.nnnRESULTSnBaseline GNRI was significantly correlated with MIS (r = -0.487, P < .0001) and SGA (r = 0.234, P < .0001). When MIS >or=6 was defined as malnutrition, the sensitivity and specificity of GNRI <or=93 in predicting malnutrition were 68.0% and 67.7%, respectively. When SGA <or=5 was used to define malnutrition, the sensitivity and specificity were 54.5% and 71.1%, respectively. The change in GNRI was correlated with the change in MIS (r = -0.244, P = .012) and overall SGA score (r = 0.266, P = .006), respectively. When an increase in MIS was defined as a worsening of nutrition, the sensitivity and specificity of GNRI were 45.7% and 81.7%, respectively. When a decrease in SGA was used to define a worsening of nutrition, the sensitivity and specificity were 42.3% and 87.0%, respectively.nnnCONCLUSIONSnAlthough GNRI is significantly correlated with other nutritional indices, it is not sensitive for screening malnutrition in PD patients. Serial measurements of GNRI are also not sensitive in detecting a change in nutritional status. Further study is needed to identify a simple and reliable tool for the assessment and monitoring of nutritional status in PD patients.

Prognostic value of arterial pulse wave velocity in peritoneal dialysis patients.

Background: Cardiovascular disease is the most common cause of mortality in chronic peritoneal dialysis (PD) patients. Increased arterial stiffness may be related to a high peritoneal permeability, resulting in fluid overload of PD patients. We examined the prognostic value and factors that govern the longitudinal change of arterial pulse wave velocity (PWV) in Chinese PD patients. Method: We enrolled 155 new PD patients. PWV was measured at baseline and then repeated after 2 years of follow-up. Results: At 24 months, the survival of patients with baseline carotid-femoral (CF)-PWV above 10 m/s was significantly worse than that of those with CF-PWV below 10 m/s (76.1 vs. 88.6%, p = 0.006). However, after adjusting for confounding factors, CF-PWV was not an independent predictor of survival. Amongst the 100 patients who had repeated PWV measurement after 2 years, the average CF-PWV increased from 9.92 ± 2.04 to 11.00 ± 2.30 m/s (p < 0.0001). The change in CF-PWV over 2 years significantly correlated with systolic blood pressure (r = 0.241, p = 0.036), serum calcium level (r = 0.231, p = 0.044), and normalized protein nitrogen appearance (NPNA) (r = –0.337, p = 0.001). Conclusions: A high baseline CF-PWV was associated with a lower overall survival of Chinese PD patients, but the prognostic value of CF-PWV disappeared after adjusting for confounding factors. After 2 years of PD, most patients had progressive increase in CF-PWV; the magnitude of increase is related to systolic blood pressure, serum calcium level, and baseline NPNA. Further study is needed to determine whether serial measurement of CF-PWV provides additional prognostic information.

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.

PREDICTORS OF RESIDUAL RENAL FUNCTION DECLINE IN PATIENTS UNDERGOING CONTINUOUS AMBULATORY PERITONEAL DIALYSIS

♦ Background: Residual renal function (RRF) is an important prognostic indicator in continuous ambulatory peritoneal dialysis (CAPD) patients. We determined the predictors of RRF loss in a cohort of incident CAPD patients. ♦ Methods: We reviewed the record of 645 incident CAPD patients. RRF loss is represented by the slope of decline of residual glomerular filtration rate (GFR) as well as the time to anuria. ♦ Results: The average rate of residual GFR decline was -0.083 ± 0.094 mL/min/month. The rate of residual GFR decline was faster with a higher proteinuria (r = -0.506, p < 0.0001) and baseline residual GFR (r = -0.560, p < 0.0001). Multivariate analysis showed that proteinuria, baseline residual GFR, and the use of diuretics were independent predictors of residual GFR decline. Cox proportional hazard model showed that proteinuria, glucose exposure, and the number of peritonitis episodes were independent predictors of progression to anuria, while a higher baseline GFR was protective. Each 1 g/day of proteinuria is associated with a 13.2% increase in the risk of progressing to anuria, each 10 g/day higher glucose exposure is associated with a 2.5% increase in risk, while each peritonitis episode confers a 3.8% increase in risk. ♦ Conclusions: Our study shows that factors predicting the loss of residual solute clearance and urine output are different. Proteinuria, baseline residual GFR, and the use of diuretics are independently related to the rate of RRF decline in CAPD patients, while proteinuria, glucose exposure, and the number of peritonitis episodes are independent predictors for the development of anuria. The role of anti-proteinuric therapy and measures to prevent peritonitis episodes in the preservation of RRF should be tested in future studies.

Repeat Peritonitis in Peritoneal Dialysis: Retrospective Review of 181 Consecutive Cases

BACKGROUND AND OBJECTIVESnThe clinical behavior of repeat-peritonitis episodes, defined as peritonitis with the same organism occurring more than 4 weeks after completion of therapy for a prior episode, is poorly understood.nnnDESIGN, SETTING, PARTICIPANTS, & MEASUREMENTSnWe compared outcomes of 181 episodes of repeat peritonitis from 1995 to 2009 (Repeat Group) with 91 episodes of relapsing peritonitis (Relapsing Group) and 125 episodes of peritonitis preceded 4 weeks or longer by another episode with a different organism (Control Group).nnnRESULTSnIn Repeat Group, 24% were due to Staphylococcus aureus, as compared with 5.5% in Relapsing Group and 15% in Control Group. The majority of the organisms causing relapsing peritonitis were Gram negative (62%), whereas the majority of that in Repeat Group were Gram positive (56%). Repeat Group had a lower complete-cure rate (70.7% versus 54.9%) than Relapsing Group, but rates of primary response, catheter removal, and mortality were similar. Repeat Group had a higher primary response rate (89.0% versus 73.6%) and a lower rate of catheter removal (6.1% versus 15.2%) than Control Group, whereas the complete-cure rate and mortality were similar. Repeat Group had a higher risk of developing relapsing (14.3% versus 2.2%) and repeat peritonitis (26.1% versus 5.4%) than Control Group, whereas the risk of recurrent peritonitis was similar.nnnCONCLUSIONSnRepeat peritonitis is a distinct clinical entity. Although repeat-peritonitis episodes generally have a satisfactory response to antibiotic, they have a substantial risk of developing further relapsing or repeat peritonitis.