Canadian Organ Replacement Register Research Articles

Effect of renal center characteristics on mortality and technique failure on peritoneal dialysis

Recent studies report decreased mortality in patients on peritoneal dialysis (PD) over time, suggesting that advances in PD have resulted in improved patient outcomes. Our investigation sought to assess the effect of renal center characteristics on mortality and technique failure (TF) rates. Covariates of interest included center-specific cumulative number of PD patients treated, percentage of patients who initiated dialysis on PD, and academic status. Using data obtained from the Canadian Organ Replacement Register, the 17,900 patients who received PD during the 1981 to 1997 period were studied. Mortality and TF rate ratios (RR) were estimated using Poisson regression, adjusting for age, gender, race, primary renal diagnosis, province, follow-up time, and type of PD. As the cumulative number of PD patients treated increased, covariate-adjusted mortality significantly decreased (P < 0.05); a weaker yet significant association was observed between number of PD patients treated and TF. As the percentage of patients initiating dialysis on PD increased, TF rates decreased significantly. No association was observed between center academic status and PD mortality or TF rates. These results imply that a center's experience with and degree of specialization toward PD impact strongly on PD outcomes. One hypothesis is that a center's propensity to exploit technical and non-technical advances in PD increases directly with these variables. It is also possible that, through experience, centers become more adept at identifying appropriate patients to receive PD. More detailed research is required to evaluate these hypotheses.

Early referral is essential for successful pediatric small bowel transplantation: The Canadian experience

Purpose: The mortality rate for pediatric patients on the waiting list for transplantation has a major impact on the overall effectiveness of pediatric small bowel transplantation. This review was undertaken to determine the fate of Canadian children assessed for small bowel transplant and the outcome of those who undergo transplant in the tacrolimus era. Methods: The authors reviewed retrospectively all of the pediatric small bowel patients listed since 1988 through the Canadian Organ Replacement Register and all the children referred to our program in its first year. All children who received a small bowel transplant between January 1993 and December 1999 also were reviewed. Results: The mortality rate for pediatric patients on the small bowel transplant list was 53% after an average of 105 days on the list compared with 212 days for those who underwent transplant. Patients who died while on the list were younger and had signs of advanced liver disease at the time of listing. Thirteen Canadian children have received a small bowel transplant with an overall 1-year patient and graft survival rate of 61% and 53%, respectively. Survivors are all independent from total parenteral nutrition. Conclusion: Many Canadian children miss their opportunity for a successful small bowel transplant because of late referrals and a shortage of donor organs. J Pediatr Surg 36:681-684. Copyright © 2001 by W.B. Saunders Company.

Cardiac risk factors and the use of cardioprotective medications in patients with chronic renal insufficiency

Cardiovascular Disease (CVD) is a major cause of morbidity and mortality among patients with chronic renal insufficiency (CRI). β-Adrenergic blockers, acetylsalicylic acid (ASA), angiotensin-converting enzyme (ACE) inhibitors, and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) all reduce CVD mortality, but little is known about the extent to which these medications are used in patients with CRI. This study, a prospective cross-sectional study of consecutive patients seen by nephrologists in four Canadian centers for follow-up of progressive CRI in 1999, was performed to investigate the prevalence of coronary risk factors and use of cardioprotective medications among patients with CRI. Patients had creatinine clearances of 75 mL/min or less but were not on dialysis therapy. Three hundred four consecutive patients meeting the inclusion criteria were enrolled. Mean age was 60.8 ± 15.7 years, mean creatinine clearance was 30.3 ± 18 mL/min, and the case mix of kidney diseases was similar to that in the Canadian Organ Replacement Registry data. One hundred seventeen of 304 patients (38.5%) had a history of previous CVD, and the prevalence of CVD was greater in patients with more severe CRI. Two hundred forty-three patients (79.9%) had a history of hypertension, 132 patients (43.4%) had hyperlipidemia, 114 patients (37.5%) had diabetes mellitus, and 71 patients (27.3%) were smokers. Thirty-five percent of the patients with CVD had blood pressures greater than 140/90 mm Hg; 103 patients (33.9%) were administered β-blockers; 196 patients (64.5%), ACE inhibitors or angiotensin-receptor blockers; 83 patients (27.3%), ASA; and 56 patients (18.4%), statins. Patients with diabetes were not more likely than those without diabetes to be prescribed cardioprotective medications. CVD is common in the predialysis population, and its prevalence increases with more severe kidney failure. Despite this, the use of cardioprotective medications is relatively low, and many patients had suboptimal blood pressure control. Given the high burden of disease in these patients, β-blockers and ACE inhibitors should be used to control hypertension and/or for cardioprotection, and the increased use of ASA and statins should be considered.

Cardiac risk factors and the use of cardioprotective medications in patients with chronic renal insufficiency

Cardiovascular Disease (CVD) is a major cause of morbidity and mortality among patients with chronic renal insufficiency (CRI). β-Adrenergic blockers, acetylsalicylic acid (ASA), angiotensin-converting enzyme (ACE) inhibitors, and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) all reduce CVD mortality, but little is known about the extent to which these medications are used in patients with CRI. This study, a prospective cross-sectional study of consecutive patients seen by nephrologists in four Canadian centers for follow-up of progressive CRI in 1999, was performed to investigate the prevalence of coronary risk factors and use of cardioprotective medications among patients with CRI. Patients had creatinine clearances of 75 mL/min or less but were not on dialysis therapy. Three hundred four consecutive patients meeting the inclusion criteria were enrolled. Mean age was 60.8 ± 15.7 years, mean creatinine clearance was 30.3 ± 18 mL/min, and the case mix of kidney diseases was similar to that in the Canadian Organ Replacement Registry data. One hundred seventeen of 304 patients (38.5%) had a history of previous CVD, and the prevalence of CVD was greater in patients with more severe CRI. Two hundred forty-three patients (79.9%) had a history of hypertension, 132 patients (43.4%) had hyperlipidemia, 114 patients (37.5%) had diabetes mellitus, and 71 patients (27.3%) were smokers. Thirty-five percent of the patients with CVD had blood pressures greater than 140/90 mm Hg; 103 patients (33.9%) were administered β-blockers; 196 patients (64.5%), ACE inhibitors or angiotensin-receptor blockers; 83 patients (27.3%), ASA; and 56 patients (18.4%), statins. Patients with diabetes were not more likely than those without diabetes to be prescribed cardioprotective medications. CVD is common in the predialysis population, and its prevalence increases with more severe kidney failure. Despite this, the use of cardioprotective medications is relatively low, and many patients had suboptimal blood pressure control. Given the high burden of disease in these patients, β-blockers and ACE inhibitors should be used to control hypertension and/or for cardioprotection, and the increased use of ASA and statins should be considered.

Sex inequality in kidney transplantation rates.

Men in the United States undergoing renal replacement therapy are more likely than women to receive a kidney transplant. However, the ability to pay may, in part, be responsible for this finding. To compare adult male and female transplantation rates in a setting in which equal access to medical treatment is assumed. Using data from the Canadian Organ Replacement Register, the rate of first transplantations was computed for the 20, 131 men and the 13,458 women aged 20 years or older who initiated renal replacement therapy between January 1, 1981, and December 31, 1996. Poisson regression analysis was used to estimate the male-female transplantation rate ratio, adjusting for age, race, province, calendar period, underlying disease leading to renal failure, and dialytic modality. Actuarial survival methods were used to compare transplantation probability for covariable-matched cohorts of men and women. Men experienced 20% greater covariable-adjusted kidney transplantation rates relative to women (rate ratio, 1.20; 95% confidence interval, 1.13-1.27). The sex disparity was stronger for cadaveric transplants (rate ratio, 1.23) compared with those from living donors (rate ratio, 1.10). The 5-year probability of receiving a transplant was 47% for men and 39% for women within covariable-matched cohorts (P<.001). The sex disparity in transplantation rates increased with increasing age. The sex effect was weaker among whites and Oriental persons (Chinese, Japanese, Vietnamese, Cambodian, Laotian, Filipino, Malaysian, Indonesian, and Korean) and stronger among blacks, Asian Indians (Indian, Pakistani, and Sri Lankan), and North American Indians (aboriginal). Since survival probability and quality of life are superior for patients who undergo transplantation relative to those who undergo dialysis, an increased effort should be made to distribute kidneys available for transplantation more equitably by sex among patients undergoing renal replacement therapy.

Projecting renal replacement therapy–specific end-stage renal disease prevalence using registry data

Projecting renal replacement therapy–specific end-stage renal disease prevalence using registry data. End-stage renal disease incidence and prevalence are increasing in many countries worldwide. Projections of ESRD prevalence are useful for forecasting future resource requirements, and organ failure registry databases are valuable for the development of appropriate projection models. We outline one method of generating renal replacement therapy (RRT)–specific ESRD prevalence projections based on data obtained from the Canadian Organ Replacement Register (CORR). To illustrate the methods, we present national RRT-specific prevalence projections for Canada to the year 2005. Continued large increases in ESRD incidence and prevalence are projected, particularly among diabetics. As of December 31, 1996, there were 17,807 patients receiving RRT in Canada. This number is projected to climb to 32,952 by the end of 2005, for a relative increase of 85% (average relative increase of 5.8% per year). Registry data are a useful basis for future health care planning.

Sex differences in renal transplantation in Canada.

To determine if a patient's sex influences access to renal transplantation in Canada, transplant recipient data for first cadaveric unrelated renal transplants were obtained from the Canadian Organ Replacement Register (CORR) for the period 1985-1992. There were 4683 first unrelated cadaveric transplant recipients during this time. Differences in the proportion of men and women registered with CORR who received a renal transplant were analyzed. In Canada between 1985 and 1992, 25% of males 40 years and older on dialysis received renal transplants compared with 18% of females (p < 0.0001, RR 1.54, 95% CI 1.40-1.67). There was no difference in the rates of transplants in males and females who were under 40 years of age. Adjusting for panel-reactive antibody data did not change the significance of the difference in transplant rates between the sexes. In Canada from 1985 to 1992, male patients with end-stage renal disease received proportionately more transplants than females.

Higher risk for renal failure in first-degree relatives of white patients with end-stage renal disease: A population-based study

To explore the possibility that hereditary factors increase the risk for end-stage renal disease (ESRD), 669 patients with ESRD in the province of Newfoundland, Canada from 1987 to 1993 were studied. Detailed family histories were obtained from 584 (87%) consecutive probands and 499 spousal control subjects. Diseases with a Mendelian pattern of inheritance accounted for 8.4% of the cases; 4.5% of the cases were caused by autosomal dominant polycystic kidney disease (ADPKD). Glomerulonephritis was the original cause of renal failure in 25% of the probands, diabetes mellitus (DM) in 20%, unknown in 14%, interstitial kidney disease in 11%, other disease in 12%, multifactorial in 4%, and hypertension in 5%. In the group without a Mendelian pattern of inheritance, 28% of the probands had a first-, second-, or third-degree relative with renal failure associated with death or dialysis versus 15% of the controls. Compared with 0.4% of the control group, 1.2% of the first-degree relatives of probands developed renal failure (odds ratio [OR]=3.0; 95% confidence interval [CI], 1.7 to 5.2). No difference was observed when risks were compared for second-degree relatives, but a highly significant increased risk was observed for third-degree relatives (OR=2.1; 95% CI, 1.2 to 3.4). The highest rates of affected first-degree relatives occurred in probands with hypertensive renal failure (2.3%), DM (1.6%), and interstitial kidney disease (1.6%). The annual provincial incidence of ESRD, registered with the Canadian Organ Replacement Registry (CORR) from 1981 to 1993 was 79 per million, excluding the 8% of patients with Mendelian inherited disease. The similar rate of ESRD in first-degree relatives of probands without Mendelian inherited disease was 297 per million. We conclude that not only is the contribution of Mendelian inherited diseases to ESRD high, but there is also an increased risk for renal failure in first-degree relatives of probands without a Mendelian inherited renal disease in a white population.

Comparing Mortality Rates on Capd/Ccpd and Hemodialysis the Canadian Experience: Fact or Fiction?

To compare mortality rates on hemodialysis (HD) to rates on continuous ambulatory/cyclic peritoneal dialysis (CAPD/CCPD), to contrast our results with those of other recent investigations, and to discuss reasons for discrepancies. Patient-specific data obtained from the Canadian Organ Replacement Register on patients initiating renal replacement therapy (RRT) between 1 January 1990 and 31 December 1995 (n = 14 483). Recent mortality comparisons of CAPD and HD. Mortality rate ratio (RR) based on "as-treated" (AT) analysis incorporating treatment modality switches and adjusting for age, primary renal diagnosis, and comorbid conditions using Poisson regression. Hazard ratios (HR) were estimated using Cox regression and based on an "intent-to-treat" (ITT) analysis wherein patients were classified based on dialytic modality received on follow-up day 90. Adjusted mortality rates were significantly decreased on CAPD/CCPD relative to HD [RR = 0.73, 95% confidence interval (CI) = (0.69, 0.77)] based on the AT analysis. Most of the protective effect of CAPD/CCPD was concentrated in the first 2 years of follow-up post-RRT initiation. Based on the ITT analysis, the estimated CAPD/ CCPD effect was greatly reduced, with HR = 0.93 (0.87, 0.99). We provide further evidence that CAPD/CCPD is not an inferior dialytic modality to HD, particularly in the short term. Comparing mortality rates on CAPD/CCPD and HD is inherently difficult due to the potential for bias. Discrepancies between our results and those of previous investigations, and variability in findings among previous studies, relate to differences in clinical and demographic setting, patient populations, study design, statistical methods, and interaction between the dialytic modality effect and various other covariables.

End-stage renal disease projections for Canada to 2005 using Poisson and Markov models.

End-stage renal disease (ESRD) incidence and prevalence are increasing in many countries worldwide. Due to the high cost of therapy, predicting future numbers of patients requiring dialysis and transplantation is necessary for health care planners. Projecting therapy-specific chronic disease prevalence is inherently problematic, and examples of suitable models and their application are sparse. When applied, rarely was the adequacy of such models evaluated. We describe and illustrate a method for projecting therapy-specific ESRD prevalence in Canada for 1995-2005 using data obtained from the Canadian Organ Replacement Register. The projections combine the Poisson model for incidence rates and a Markov model for patient follow-up. Model adequacy is empirically validated by data-splitting. Large increases in ESRD prevalence are expected in Canada, with an average annual increase of 6.9% projected for 1995-2005. Upon validation, the projection model based on 1981-1987 data was able to predict 1994 prevalence within 1%, while projected therapy-specific prevalences closely approximated those observed. Therapy-specific ESRD prevalence was successfully projected using Poisson and Markov models. Where multistate prevalence forecasts are required, the method could be augmented for application to various other chronic diseases.

Hemodialysis versus peritoneal dialysis: A comparison of adjusted mortality rates

Although kidney transplantation is the preferred treatment method for patients with ESRD, most patients are placed on dialysis either while awaiting transplantation or as their only therapy. The question of which dialytic method provides the best patient survival remains unresolved. Survival analyses comparing hemodialysis and continuous ambulatory peritoneal dialysis/continuous cyclic peritoneal dialysis (CAPD/CCPD), a newer and less costly dialytic modality, have yielded conflicting results. Using data obtained from the Canadian Organ Replacement Register, we compared mortality rates between hemodialysis and CAPD/CCPD among 11,970 ESRD patients who initiated treatment between 1990 and 1994 and were followed-up for a maximum of 5 years. Factors controlled for include age, primary renal diagnosis, center size, and predialysis comorbid conditions. The mortality rate ratio (RR) for CAPD/CCPD relative to hemodialysis, as estimated by Poisson regression, was 0.73 (95% confidence interval: 0.68 to 0.78). No such relationship was found when an intent-to-treat Cox regression model was fit. Decreased covariable-adjusted mortality for CAPD/CCPD held within all subgroups defined by age and diabetes status, although the RRs increased with age and diabetes prevalence. The increased mortality on hemodialysis compared with CAPD/CCPD wa concentrated in the first 2 years of follow-up. Although continuous peritoneal dialysis was associated with significantly lower mortaltiy rates relative to hemodialysis after adjusting for known prognostic factors, the potential impact of unmeasured patient characteristics must be considered. Notwithstanding, we present evidence that CAPD/CCPD, a newer and less costly method of renal replacement therapy, is not associated with increased mortality rates relative to hemodialysis.

Renal replacement therapy in Canada: A report from the Canadian Organ replacement register

We report here the demography and results of renal replacement therapy in Canada from 1981 to 1992. The new case rate for patients entering renal replacement therapy programs in Canada has increased dramatically over the last 12 years, from 49.9 per million to 98.4 per million of the population. The largest increases have been among the elderly, from 146.2 per million in 1981 to 381.9 per million in 1992 for those aged 65 to 74 years. There has been an even more dramatic increase for those over 75 years, from 83.6 per million in 1981 to 261.6 per million in 1992. There has been a similar increase in the prevalence rate, with an increase from 229.1 per million in 1981 to 518.5 per million in 1992. The hemodialysis rate for 1992 was 172.2 per million and that for peritoneal dialysis was 103.1 per million of the population. The renal transplantation rate also increased from 20 per million in 1981 to 34.8 per million in 1988, but unfortunately has decreased to 27.5 per million in 1992. Diabetes is now the most common primary renal diagnosis, having increased from 15% in 1981 to 24% in 1992. The 5-year survival rate of all patients on renal replacement therapy was 55%. For nondiabetic patients, the 5-year survival rate ranged from 85% for the those aged 15 to 44 years to 20% for those over 65 years. Among diabetic patients, the 5-year survival rate declined from 58% for the 15 to 44 year age group to 10% for those over 65 years.

Renal function recovery in end-stage renal disease.

Renal function recovery (RFR) is a rare event in patients with end-stage renal disease (ESRD). Although some predictive factors have been described, there are still unresolved questions. We have analyzed the Canadian Organ Replacement Register data for the 1981 to 1989 period to assess the incidence and factors predictive of RFR in a large ESRD population as well as the outcome after recovery. Renal function recovery was defined as the interruption of renal replacement therapy (RRT) for more than 3 months. Patients on RRT for < or = 45 days were excluded. Of 14,318 registered ESRD patients, 342 (2.4%) experienced RFR after 8.9 +/- 0.5 months of RRT (mean +/- SEM); 52.3% of the recoveries occurred within 6 months of initiating RRT, while 23.7% were only observed after 12 months or more. By Cox regression, patients within the following diagnostic groups had a significantly higher rate of RFR than those with primary glomerulonephritis, who are considered to comprise the reference group: myeloma (relative rate [RR] = 6.00; P < 0.001), drug-induced disease (RR = 4.21; P < 0.001), vascular/hypertensive disease (RR = 2.60; P < 0.001), and systemic disease (RR = 2.58; P < 0.001). Inversely, patients with polycystic kidneys (RR = 0.06; P = 0.004) and diabetic patients (RR = 0.56; P = 0.024) had a lower rate of RFR than those with glomerulonephritis. Men younger than 45 years had a lower rate of RFR than older men and women of all ages (P < or = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Third internat. symposium on quantum electronics : M. Y. Bernard, L'Onde Electrique, pp. 721–737 (July–Aug. 1963)

To explore the possibility that hereditary factors increase the risk for end-stage renal disease (ESRD), 669 patients with ESRD in the province of Newfoundland, Canada from 1987 to 1993 were studied. Detailed family histories were obtained from 584 (87%) consecutive probands and 499 spousal control subjects. Diseases with a Mendelian pattern of inheritance accounted for 8.4% of the cases; 4.5% of the cases were caused by autosomal dominant polycystic kidney disease (ADPKD). Glomerulonephritis was the original cause of renal failure in 25% of the probands, diabetes mellitus (DM) in 20%, unknown in 14%, interstitial kidney disease in 11%, other disease in 12%, multifactorial in 4%, and hypertension in 5%. In the group without a Mendelian pattern of inheritance, 28% of the probands had a first-, second-, or third-degree relative with renal failure associated with death or dialysis versus 15% of the controls. Compared with 0.4% of the control group, 1.2% of the first-degree relatives of probands developed renal failure (odds ratio [OR]=3.0; 95% confidence interval [CI], 1.7 to 5.2). No difference was observed when risks were compared for second- degree relatives, but a highly significant increased risk was observed for third-degree relatives (OR=2.1; 95% CI, 1.2 to 3.4). The highest rates of affected first-degree relatives occurred in probands with hypertensive renal failure (2.3%), DM (1.6%), and interstitial kidney disease (1.6%). The annual provincial incidence of ESRD, registered with the Canadian Organ Replacement Registry (CORR) from 1981 to 1993 was 79 per million, excluding the 8% of patients with Mendelian inherited disease. The similar rate of ESRD in first-degree relatives of probands without Mendelian inherited disease was 297 per million. We conclude that not only is the contribution of Mendelian inherited diseases to ESRD high, but there is also an increased risk for renal failure in first-degree relatives of probands without a Mendelian inherited renal disease in a white population. (Am J Kidney Dis 1998 Nov;32(5):794-801)