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Biomedical subjects

S S Fenton

Publications and source records attributed to S S Fenton.

At least 19 recordsLinked to original sources
PubMed1998

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Adult↗
PubMed1997

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 was concentrated in the first 2 years of follow-up. Although continuous peritoneal dialysis was associated with significantly lower mortality 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.

Adolescent↗
PubMed1997

The Canadian Organ Replacement Register on renal replacement therapy.

This report describes the demography, clinical characteristics, and outcomes for patients receiving renal replacement therapy (RRT) in Canada. Results are based on registered patients initiating RRT during the 1981-85 period using data obtained from the Canadian Organ Replacement Register (CORR).

Canada↗
PubMed1996

The Canadian Organ Replacement Register.

The analyses presented in this chapter are a subset of the yearly audit of organ donation and transplantation in Canada published in the CORR Annual Report. They represent the collaborative efforts and the voluntary contributions of many of the transplant physicians, surgeons, nurses and coordinators in Canada. In Canada, organ donation has remained static at approximately 14 per million population. Despite many local and provincial as well as corporate initiatives, this rate is approximately half the current rate in many regions of the U.S.A. and Spain. The modest increases in transplant activity represent an increase in the use of living donors, reassessment of the traditional donor risk factors (including age) and expansion of the potential donors for each organ. Analysis of the renal transplant activity has determined that the likelihood of being transplanted during the first year on the list was less than 40%. A graft loss rate of 4% per year after the first year was observed for a cadaveric kidney, compared with graft loss rates of 3% and 2% per year for living-related and living-unrelated donor kidneys, respectively. Cox regressional analysis identified that the major determinants of patient survival were the transplant year, the region where the transplant was performed, the presence of diabetes, the recipient's age, and whether the kidney was from a living donor. Liver transplantation has increased each year at the transplant centers in Vancouver, Edmonton, London, Toronto, Montreal, and Halifax. Patient and graft survival rates have improved since 1985 and the most significant determinant of patient survival following transplantation was the patient's medical status at the time of transplantation. Living-related liver donor transplant programs have begun in London and Toronto. Pancreas transplantation remains limited across Canada, but with the development of new pancreas programs in Toronto and Halifax, an increase in the availability of this therapy for Type 1 diabetics is anticipated. Heart transplantation has recovered from a decline in 1991-1992 to approximately 6 hearts per million population. There has been a trend towards better one- and 3-year patient survival rates since 1985. With the development of a lung transplantation program in Winnipeg, lung transplantation has increased. This likely reflects increased utilization of the available donor lungs. A particular increase in double-lung transplants was noted.

Adolescent↗
PubMed1994

A comparison of rabbit antithymocyte serum and OKT3 as prophylaxis against renal allograft rejection.

A total 166 first cadaveric renal allograft recipients were randomly assigned to receive either rabbit antithymocyte serum (RATS) (n = 83) or OKT3 (n = 83) for 10 to 14 days after transplant as prophylaxis against rejection. Both groups were similar with respect to age, sex, donor age, diabetes, time on dialysis, panel-reactive antibody, HLA matching, and transfusion before transplantation. All patients were followed for 1 year after transplantation. A comparison of the rejection rates between the 2 groups of patients showed that patients receiving OKT3 had a rate of first rejection 1.87 times higher than those receiving RATS (95% confidence interval 1.18-2.8, P = 0.007). Twenty-five steroid-resistant rejections occurred in OKT3-treated patients as compared with 12 in the RATS-treated group (P < 0.05). There was no significant difference in early or late renal function between the 2 groups of patients. Actuarial 1-year graft survival for the RATS group was 78% and for the OKT3 group, 80.7% (P = NS). Actuarial 1-year patient survival was similar: 89.5% in the RATS group and 94.6% in the OKT3 group (P = NS). Total hospitalization time was 29.8 +/- 19.9 days for RATS vs. 39.5 +/- 22.1 days for those treated with OKT3 (P < 0.006). A number of infections were observed but there were no significant differences between the groups. We conclude that RATS provides better prophylaxis than OKT3 in first cadaveric renal transplants because it is associated with fewer rejection episodes, less hospitalization, and no additional morbidity or mortality.

Adult↗
PubMed1993

The spectrum of bone disease in end-stage renal failure--an evolving disorder.

We have assessed the bone histology in 259 chronic dialysis patients, all of whom were in the same dialysis program. All patients had bone biopsies with quantitative histomorphometry, intact parathyroid hormone (PTH) measurements, basal and deferoxamine stimulated serum aluminum levels. Results demonstrate the increased incidence of the recently described aplastic bone lesion, particularly in patients treated with peritoneal dialysis (PD). Aluminum-related bone disease is much less common than previously described, perhaps in relation to the declining use of aluminum as a phosphate binder. A different pattern of bone lesions is seen in PD as compared with hemodialysis (HD), with low turnover disorders comprising 66% of the lesions seen in PD and high turnover lesions accounting for 62% of the bone histologic findings in HD. The difference in these patterns may relate to alterations in PTH levels, as mean PTH levels in HD patients were 2-1/2 times the levels found in PD patients (P < 0.0005), while older age, higher prevalence of diabetes and a shorter duration of dialysis may also have contributed to the findings in the PD patients. We suggest that PD, perhaps by maintaining calcium at higher levels, may more effectively suppress the parathyroid gland.

Adult↗
PubMed1993

Dialysis therapy among elderly patients; data from the Canadian Organ Replacement Register, 1981-1991.

Reports of clinical outcomes after commencement of dialysis treatment among elderly patients with end-stage renal disease (ESRD) are not been numerous. This paper describes the demographic and clinical characteristics of the elderly treated for ESRD in Canada using the Canadian Organ Replacement Register data. Comparisons with younger age groups are also presented. Analyses of data for the period 1981-1991 indicated that the elderly (65+) represent an expanding portion of all new ESRD patients in Canada. Distributions of dialysis modalities showed no major differences by age groups (45-54, 55-64, 65-75, 75+). However, the overall usage of intermittent peritoneal dialysis has decreased over time (from 17% of patients in 1981-83 to 7% in 1990-91). Deaths from social causes were slightly more frequent among the elderly (15.9% of all deaths among those aged 65+ vs 10% among those aged 45-64). Moreover, deaths from infections were more common among patients on dialysis for a longer period of time and more common among patients on peritoneal dialysis than among those on hemodialysis. Discontinuations of continuous ambulatory peritoneal dialysis (CAPD) because of the inability to cope increased with age. Patients with comorbid conditions were more likely to receive hemodialysis, and, as expected, the presence of these conditions increased with age and significantly reduced survival. Other determinants of survival included calendar period of registration, renal center size, and treatment modality. This paper illustrates the many changes over time in the elderly population treated for ESRD. Also of importance, however, is the elderly Canadian population with ESRD which is not presently treated.

Age Factors↗
PubMed1990

Results from the Canadian Renal Failure Registry.

This report encompasses data collected from all Canadian patients starting treatment for end-stage renal failure (ESRF) from 1981 until the end of 1987. Gross mortality showed an initial decline, but has stabilized since 1985. The year of entry into the system did not change the survival rate. There was an increase in the rate of acceptance of new patients between 1982 and 1987. The largest increases were in the older age groups, and resulted in a concomitant increase in the number of registered patients in older age groups. Survival on dialysis by age group declined with age. There was no difference in patient survival on hemodialysis or peritoneal dialysis. The probability of death for all patients entering the ESRF system remained constant notwithstanding year of entry into the system. It was slightly higher for males than females, much higher for patients with diabetes or renal vascular disease, higher with age, and much higher for patients not undergoing transplant.

Adolescent↗
PubMed1988

Aluminum toxicity to the brain.

The association between elevated brain aluminum levels and Alzheimer's disease (AD) is examined and critically reviewed. We found elevated aluminum levels in the brains of patients with AD (greater than 4 micrograms/g dry wt.) compared with normal subjects (approximately 1.5 micrograms/g dry wt.). Nine laboratories from different geographical regions have confirmed this finding. Two laboratories did not find any differences between AD and control brains. This discrepancy is traced to differences in sample sizes used for the aluminum assay and the sample selection criteria. It is found that it is essential to use small sizes (approximately 10 mg dry wt.) and to ensure that control brains do not contain neurofibrillary tangles (NFT) and that AD brains do. The exact pathogenic role of aluminum in AD is, as yet, unclear. It is the only element (other than calcium, which non-specifically accumulates at all degenerating tissue sites) that is found in elevated concentrations in NFTs. It is found elevated at four loci in the brain, i.e. the DNA-containing structures of the nucleus, the protein moities of NFTs, the amyloid cores of senile plaques and cerebral ferritin. The evidence thus far indicates that aluminum is toxic to the brain and it is probable that it has a pathogenic role in Alzheimer's disease.

Aluminum↗
PubMed1988

Early function as the principal correlate of graft survival. A multivariate analysis of 200 cadaveric renal transplants treated with a protocol incorporating antilymphocyte globulin and cyclosporine.

We examined the factors determining graft survival in 200 consecutive cadaveric renal transplants managed on a quadruple-therapy protocol: Minnesota antilymphoblast globulin, cyclosporine, azathioprine, and low-dose prednisone. Perioperative central venous pressure monitoring and volume expansion were emphasized. To avoid CsA nephrotoxicity in the early posttransplant period, patients were treated with ALG until renal function was established (a mean of 7 days). Therapeutic CsA levels were achieved before ALG was discontinued. Azathioprine was used to supplement CsA in patients with nephrotoxicity or rejection. Twelve-month graft survival was 85% (first transplants 86%, retransplants 79%), with patient survival of 95%. ALG was not associated with excessive clinical cytomegalovirus infections, which occurred in 5% of patients, or with malignancy. When 3 technical failures were excluded, an analysis of numerous factors in the pretransplant and peritransplant period revealed that the strongest correlate of one-year graft survival was early renal function. Grafts with delayed function (DF) had 75% survival, compared with 91% for grafts with good early function (EF). A multivariate analysis confirmed this association: the relative risk of graft loss was increased 2.86 times for DF compared with EF. The mechanism of the deleterious effect of DF was apparently multifactorial: the DF group, by definition, contained all the kidneys that never functioned, but some risk also persisted in kidneys that achieved function. One reason for this may be that DF kidneys that achieved function had higher mean serum creatinine values at 1 month: elevated serum creatinine values at 1 month were strongly associated with increased risk of graft loss regardless of initial function. There was also a higher number of rejection episodes diagnosed in the DF group. These observations suggest that early renal function is a major determinant of graft outcome and should be a target for efforts to further improve renal graft survival.

Antilymphocyte Serum↗
PubMed1987

Right atrial ball thrombus as a complication of subclavian catheter insertion for hemodialysis access.

In two patients right atrial ball thrombi developed following prolonged subclavian cannulation for hemodialysis. One patient died, the other had the ball thrombus removed by open heart surgery. It appears that repeated friction of the catheter tip may have damaged the endothelium of the right atrial wall. This hitherto unrecognised complication might be prevented by ensuring that subclavian hemodialysis catheters are never allowed to reach as far as the right atrium.

Adult↗
PubMed1986

Analysis of biological thiols: determination of thiol components of disulfides and thioesters.

This report describes a method for using selective cleavage of thioesters to allow differentiation between thioesters and disulfides. The method identifies thiol components (including glutathione, coenzyme A, and cysteine) of low-molecular-weight thioesters and disulfides in cell extracts, as well as thiols bound to protein via thioester or disulfide links. Thioesters were cleaved with 200 mM hydroxylamine under a nitrogen atmosphere in the presence of monobromobimane (mBBr), which forms a fluorescent derivative with the released thiol. For analysis of disulfides, thioesters were cleaved with hydroxylamine in the presence of N-ethylmaleimide to block released thiols: disulfides were then reduced with 10 mM dithiothreitol and subsequently labeled with mBBr. The bimane derivatives were identified and quantified using previously described HPLC methods (G. L. Newton, R. Dorian, and R. C. Fahey, 1981, Anal. Biochem. 114, 383-387). Traditional methods using dithiothreitol and sodium borohydride to cleave disulfides can also cleave thioesters and thus should not be used for specific analysis of disulfides.

Animals↗
PubMed1985

The reduction in the peritonitis rate among high-risk CAPD patients with the use of the Oreopoulos-Zellerman connector.

We have described a prospective controlled study of the Oreopoulos-Zellerman peritoneal dialysis connection system which is based on the principle of chemical sterilization of the connector between each dialysis exchange. This system, in a short-term study of 27 high-risk patients, has resulted in a fourfold difference in the peritonitis rate between the concurrent control group (1/8.8 patient months) and the O-Z group (1/35.7 patient months). The probability of developing peritonitis by 6 mos was 0.15 using the O-Z connector and 0.46 in the control group.

Adult↗
PubMed1981

Symptomatic exacerbation of peripheral vascular disease with chronic ambulatory peritoneal dialysis.

Details of five patients with exacerbation of the symptoms of peripheral vascular disease on chronic ambulatory peritoneal dialysis (CAPD) are presented. The mechanisms of their vascular complications are discussed and the peripheral arterial sequelae of hypotension induced by CAPD are emphasized. These patients are compared with the other patients in the series of 121 patients. Suggestions for diagnosis and treatment of exacerbations of peripheral vascular disease in patients on CAPD are given.

Arteriosclerosis↗