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Bryce A Kiberd

Publications and source records attributed to Bryce A Kiberd.

17 recordsLinked to original sources

Serum creatinine in patients with advanced liver disease is of limited value for identification of moderate renal dysfunction: are the equations for estimating renal function better?

BACKGROUND: The Cockcroft-Gault formula (CGF) is used to estimate the glomerular filtration rate (GFR) based on serum creatinine (Cr) levels, age and sex. A new formula developed by the Modification of Diet in Renal Disease (MDRD) Study Group, based on the patient's Cr levels, age, sex, race and serum urea nitrogen and serum albumin levels, has shown to be more accurate. However, the best formula to identify patients with advanced liver disease (ALD) and moderate renal dysfunction (GFR 60 mL/min/1.73 m2 or less) is not known. The aim of the present study was to compare calculations of GFR, using published formulas (excluding those requiring urine collections) with standard radionuclide measurement of GFR in patients with ALD. METHODS: Fifty-seven consecutive subjects (40% women) with a mean age of 50 years (range 16 to 67 years) underwent 99m-technetium-diethylenetriamine pentaacetic acid (99mTc-DTPA) (single injection) radionuclide measurement of GFR. To calculate GFR, three formulas were used: the reciprocal of Cr multiplied by 100 (100/Cr), the CGF and the MDRD formulas. Pearson's correlation coefficient (r) and Bland-Altman analyses of agreement were used to analyze the association between 99mTc-DTPA clearance and the three equations for GFR. RESULTS: The mean 99mTc-DTPA clearance was 83 mL/min/1.73 m2 (range 28 mL/min/1.73 m2 to 173 mL/min/1.73 m2). Mean calculated GFRs by 100/Cr, the CGF and the MDRD formula were 106 mL/min/1.73 m2, 98 mL/min/1.73 m2 and 86 mL/min/1.73 m2, respectively. Regression analysis showed good correlation between radionuclide GFR and calculated GFR with r(100/Cr)=0.74, r(CGF)=0.80, r(MDRD)=0.87, all at P > or = 0.0001. The MDRD formula provided the least bias. The Bland-Altman plot showed best agreement between GFR calculated by the MDRD formula and 99mTc-DTPA clearance, with only 3 mL/min/1.73 m2 overestimation. There was higher variability between radionuclide GFR and calculated GFR by the CGF and by 100/Cr. Although there was no difference in precision, GFR calculated by the MDRD formula had the best overall accuracy. The sensitivity and specificity for detection of moderate renal dysfunction by the MDRD formulas were 73% and 87%, respectively. CONCLUSIONS: Among the Cr-based GFR formulas, the MDRD formula showed a larger proportion of agreement with radionuclide GFR in patients with ALD. In clinical practice, the MDRD is the best formula for detection of moderate renal dysfunction among those with ALD.

Adolescent↗

Outcomes of acute coronary syndrome in a large Canadian cohort: impact of chronic renal insufficiency, cardiac interventions, and anemia.

BACKGROUND: Chronic renal insufficiency (CRI) has been identified as an important risk factor for cardiac events. Studies in the United States reported decreased survival and decreased use of surgical and medical interventions after myocardial infarction in patients with CRI. METHODS: We studied the impact of renal function on health outcomes in a Canadian cohort of consecutive patients admitted with acute coronary syndrome (ACS) between October 1997 and October 1999. The study design is an observational cohort of 5,549 adult patients who survived to discharge with a discharge diagnosis of ACS. Renal function is classified into 4 levels: (1) normal, glomerular filtration rate (GFR) greater than 80 mL/min/1.73 m2 (>1.33 mL/s); (2) mild CRI, GFR of 60 to 80 mL/min/1.73 m2 (1.00 to 1.33 mL/s); (3) moderate CRI, GFR of 30 to 59 mL/min/1.73 m2 (0.50 to 0.98 mL/s); and (4) severe CRI, GFR less than 30 mL/min/1.73 m2 (<0.50 mL/s). The primary outcome is death. RESULTS: Advanced and moderate CRI independently predicted death (hazard ratio, 1.06; 95% confidence interval [CI], 1.01 to 1.12; and hazard ratio, 1.23; 95% CI, 1.18 to 1.29). Severe anemia (hemoglobin level < 9.0 g/dL [<90 g/L]) also was an independent risk factor for death (hazard ratio, 1.38; 95% CI, 1.18 to 1.61). Use of beta-blockers (hazard ratio, 0.91; 95% CI, 0.86 to 0.97), acetylsalicylic acid (hazard ratio, 0.90; 95% CI, 0.84 to 0.97), lipid-lowering therapy (hazard ratio, 0.84; 95% CI, 0.78 to 0.89), and medical thrombolysis (hazard ratio, 0.89; 95% CI, 0.81 to 0.97) were associated with reduced risk for death. Medical interventions with beta-blockers, acetylsalicylic acid, lipid-lowering therapy, and thrombolysis and surgical intervention were significantly less likely to be used in patients with CRI. CONCLUSION: Despite universal access to health care, Canadian patients with CRI are more likely to die after a cardiac event and less likely to receive important interventions.

Adrenergic beta-Antagonists↗

The marginal cost of satellite versus in-center hemodialysis.

BACKGROUND: Despite increasing numbers of patients receiving hemodialysis in satellite units (SHD), the economic aspects have not been widely explored. A cost analysis of SHD and in-center hemodialysis (ICHD) from a societal perspective was performed to establish the efficiencies associated with shifting resources and patients from ICHD to SHD. METHODS: Costs were classified as fixed or variable and placed into categories. The resources for operating a SHD unit are the sum of two components: total fixed costs (TFC) and average variable cost (AVC) times SHD patient volume (Q). Using the TFC of a specific-sized SHD unit and the difference in AVC between ICHD and SHD the number of patients needed (Q) in the SHD unit for financial viability was determined. The formula TFC = (AVC(ICHD) - AVC(SHD)) X Q was used to determine the number of patients (Q) needed in a specific-sized SHD unit such that the yearly cost of SHD treatment would be the same as ICHD treatment. RESULTS: Our results show that SHD fixed costs can be fully offset if the volume of SHD patients is seven per year in a six-station unit. SHD costs were lower for nursing and physician fees. Therefore, ICHD care variable costs were $11,374 more per patient year. SHD patients would also have lower travel costs, a mean cost saving of $12,364 per year. CONCLUSION: SHD can result in significant savings both to the health-care system and to patients. Using the cost categories and formula presented, the number of patients needed in a specific-sized satellite unit to realize cost savings was determined for our program. We found that these savings can offset the fixed investment needed to operate a SHD unit at modest patient volumes.

Ambulatory Care Facilities↗

Screening to prevent polyoma virus nephropathy: a medical decision analysis.

Polyomavirus nephropathy (PVN) is an emerging medical dilemma in kidney transplantation. Methods to screen before clinical disease are available and early immunosuppression reduction may change the natural history of progression. However, the consequences of an increase in rejection may limit the benefits. In a simulation model a 'screen' versus 'no-screen' strategy was compared. Baseline PVN cumulative incidence was assumed to be 4%. Patients with PVN were modeled to have 4-fold higher risk of graft loss. In the screen strategy, patients positive for blood DNA PCR had their immunosuppression reduced. This pre-emptive change was modeled to reduce progression to overt PVN by 80%. Therapy reduction was associated with a 10% risk of precipitating acute rejection and greater risk of chronic allograft loss. In the baseline case, screening saved 1912 dollars (discounted) and produced 0.020 more quality adjusted life years (QALYs) than not screening. Screening resulted in decreased net QALYs if the false positive viremia rate was >9.5% and the PVN incidence was <2.1%. Much of the cost savings of screening relate to savings from immunosuppression reduction in the screened arm. Screening may well be cost-effective if not cost saving in centers with high PVN rates. There remain significant areas of uncertainty.

Adolescent↗

Early adequate mycophenolic acid exposure is associated with less rejection in kidney transplantation.

This study examines the importance of early mycophenolic acid (MPA) exposure in the cyclosporine- and mycophenolate mofetil (MMF)-treated kidney transplant population. We prospectively evaluated 94 first solitary kidney transplant patients treated with cyclosporine (Neoral), MMF, and prednisone. Basiliximab was also given to 72 recipients. MPA exposure was measured by HPLC using a limited sampling estimate of 12 h area under the curve (AUC [0-12]) within the first week. Efficacy was determined by the occurrence of acute rejection and toxicity by the need to reduce MMF doses within the first 3 months post-transplantation. Acute rejection was observed in 14 (15%) and MMF toxicity in 27 (29%). Receiver operator curve analysis shows that MPA AUC [0-12] on day 3 was predictive of efficacy (c = 0.72, p = 0.007) but not toxicity (c = 0.57, p = 0.285). A separate analysis of only patients on basiliximab shows that the MPA AUC [0-12] on day 3 was also predictive of efficacy (c = 0.80, p = 0.01). Therefore early adequate exposure to MPA by day 3 is associated with low acute rejection but cannot predict toxicity. Adequate MPA exposure is also important with basiliximab induction therapy.

Adult↗

Screening for West Nile virus in organ transplantation: a medical decision analysis.

The Organ Procurement and Transplant Network (OPTN) has recently announced that screening for West Nile Virus (WNV) in deceased organ donors is not recommended at this time. The purpose of this report was to examine the impact of this recommendation by using medical decision analysis. Without screening the rate of disease transmission was assumed to be the same as in donated blood with a case fatality rate of 25%. With screening we assumed the baseline screening test specificity and sensitivity to be 99.5% and 95%, respectively. The analysis was confined to heart, liver and kidney recipients. Survival probabilities and transplant rates were taken from UNOS. Annual screening could result in the loss of potentially 452.4 life years (113.8 for heart, 272.6 for liver and 66.0 for kidney). Most positive test results would be false-positive. Screening would be preferable for kidney donors in areas of high disease prevalence and high test specificity. However, for heart and liver most scenarios were associated with a net loss of life with screening, except if patients were stable on the wait list with particularly high case fatality rates from WNV. Current recommendations by OPTN that screening is not mandatory seem appropriate until further data are available.

Databases as Topic↗

Screening for prostate, breast and colorectal cancer in renal transplant recipients.

American Society of Transplantation guidelines recommend screening renal transplant recipients for breast, colorectal and prostate cancer. However there is a lack of evidence to support this practice. Computer simulation modeling was used to estimate the years of life lost as a result of these cancers in 50-year-old renal transplant recipients and subjects in the general population. Renal transplant recipients lost fewer years of life to cancer than people in the general population largely because of reduced life expectancy. In nondiabetic transplant recipients, loss of life as a result of these cancers was comparable with that in the general population only under assumptions of increased cancer incidence and cancer-specific mortality risks. Even with two-fold higher cancer incidence and disease-specific mortality risks, diabetic transplant recipients lost considerably fewer life years to cancer than those in the general population. Recommended cancer screening for the general population may not yield the expected benefits in the average renal transplant recipient but the benefits will be considerably higher than for patients on dialysis. Transplanted patients at above-average cancer risk in good health may achieve the benefits of screening that are seen in the general population.

Colorectal Neoplasms↗

Albuminuria and renal insufficiency prevalence guides population screening: results from the NHANES III.

BACKGROUND: A number of screening criteria, applied either at a single point in time or serially, can be used for the purpose of identifying individuals at risk of end-stage renal disease (ESRD). This study focused on two such criteria measured on a single occasion, proteinuria and renal insufficiency, and examined their prevalence in a sample representative of the adult U.S. non-institutionalized population. Such knowledge guides the utility of population screening to prevent ESRD. METHODS: The prevalence of albuminuria (microalbuminuria and macroalbuminuria from a random urine albumin-to-creatinine ratio) and renal insufficiency [glomerular filtration rate (GFR) estimated from serum creatinine] was determined in different age categories in various adult screening groups in the cross-sectional Third National Health and Nutrition Examination Survey (NHANES III). RESULTS: A total of 14,622 adult participants were included in the analysis. In the general population, 8.3% and 1.0% of participants demonstrated microalbuminuria and macroalbuminuria, respectively. To identify one case of albuminuria, one would need to screen three persons with diabetes mellitus, seven non-diabetic hypertensive persons, or six persons over the age of 60. When albuminuria and renal insufficiency were considered together, it was clear that these tests were identifying different segments of the population; 37% of participants with a GFR less than 30 mL/min/1.73 m2 demonstrated no albuminuria. Non-albuminuric renal insufficiency was most evident in the ages of 60 to 79; 34% of diabetics, and 63% of non-diabetic hypertensives with a GFR less than 30 mL/min/1.73 m2 demonstrated no albuminuria. CONCLUSIONS: Albuminuria is prevalent, and when considered together, screening tests of albuminuria and renal insufficiency measured on a single occasion identify different segments of the population. The prevalence of albuminuria and renal insufficiency in populations of interest should be considered, as this knowledge has implications for the effectiveness of screening.

Adult↗

Quality of prereferral care in patients with chronic renal insufficiency.

BACKGROUND: Appropriate care in chronic renal insufficiency (CRI) includes blood pressure and diabetes control, as well as the investigation and management of anemia, acidosis, and bone disease. There is a lack of data on the control of these parameters at the time of referral to a nephrologist. Similarly, early referral has been emphasized in the literature, yet very little published has examined current referral patterns. METHODS: A single-center retrospective/prospective review of all new outpatient referrals to nephrologists in Halifax, Canada, in 1998 and 1999 was conducted to identify patients with CRI (serum creatinine > 1.6 mg/dL [141 micromol/L] for men or >1.2 mg/dL [106 micromol/L] for women). Quality of prereferral care was based on data from the initial clinic visit. RESULTS: Of 1,050 charts reviewed, 411 patients met the study criteria. Twenty-six percent of patients had diabetes mellitus, 18% were referred with a calculated glomerular filtration rate less than 15 mL/min, and blood pressure was optimally controlled (<130 mm Hg systolic and <80 mm Hg diastolic) in only 24%. Only 44% of patients were administered an angiotensin-converting enzyme inhibitor. Patients were administered an average of 1.9 antihypertensive agents. Significant anemia (hemoglobin < 10 g/dL) was present in 21%, and appropriate investigations were performed in only 35% of these patients. Calcium levels less than 8.6 mg/dL (2.15 mmol/L) were found in 19% of patients, and only 14% of these patients were started on calcium supplement therapy. Phosphate levels greater than 5.0 mg/dL (1.6 mmol/L) were seen in 20% of patients, and 14% of these patients were on phosphate-binder therapy. Parathyroid hormone levels were more than five times normal values in 18% of patients, and 25% of patients had bicarbonate levels less than 23 mmol/L. CONCLUSIONS: A significant proportion of patients referred with CRI receive inadequate prereferral care. Continuing education programs and referral guidelines must not only emphasize the importance of early referral, but also address the related consequences of CRI to delay the progression of renal disease and avoid complications.

Acidosis↗

Barriers to blood pressure control and angiotensin enzyme inhibitor use in Canadian patients with chronic renal insufficiency.

BACKGROUND: Current recommendations for the management of chronic renal insufficiency (CRI) include the use of angiotensin-converting enzyme inhibitors (ACEI) and achieving target blood pressure control. We designed this study to describe the use of these therapeutic strategies, and to investigate barriers to their implementation. METHODS: This was a prospective study of 304 consecutive CRI patients, seen at follow-up in four nephrology clinics across Canada. The use of blood pressure control and antihypertensive medication (AHM) in each of these clinics was recorded, and a questionnaire was administered to nephrologists to determine the basis for decisions concerning AHM regimens and ACEI use/non-use. RESULTS: Mean age was 60.8+/-15.7 years, mean creatinine clearance was 30.3+/-18 ml/min, and underlying renal diseases were similar to registry data. Mean arterial pressure (MAP) achieved was 99.4+/-14.4 and 98.9+/-11.9 mmHg in individuals with >1 and </=1 g/day proteinuria, respectively. When similarly stratified by proteinuria, mean systolic blood pressures were 141.4+/-23.5 and 140.9+/-20.3 mmHg, and mean diastolic blood pressures were 78.4+/-14.0 and 77.9+/-11.4 mmHg, respectively. Blood pressure control, according to published guidelines, was achieved in 128 patients (42.1%). A further 86 (28.3%) patients had their AHM increased. The remaining 90 (29.6%) did not have their AHM increased. Of these, 40 were labelled 'at target blood pressure' (mean MAP 100.5+/-5.4 mmHg), 19 'office hypertension' and 11 'unfavourable risk/benefit ratios'. There were 108/304 (35.5%) patients who were not taking ACEI or ARB (angiotensin receptor antagonist): 34/108 (31%) had previous ACEI failure due to hyperkalaemia (21/108, 19%) or acute renal failure (17/108, 16%), and 61/108 (55%) were felt 'unlikely to benefit' (categories not mutually exclusive). Miscommunication with the primary physician and medication costs were not identified as significant barriers to improved blood pressure control or ACEI use. CONCLUSIONS: Approximately 40% of CRI patients are achieving current blood pressure goals and 64% are prescribed ACEI/ARB in tertiary care nephrology clinics. Although the use of these strategies may be increasing, there remains room for improvement. Physicians should remain aware of the need to use these proven strategies in patients with CRI.

Angiotensin-Converting Enzyme Inhibitors↗

Prevalence of low glomerular filtration rate in nondiabetic Americans: Third National Health and Nutrition Examination Survey (NHANES III).

End-stage renal disease is an important and costly health problem. Strategies for its prevention are urgently needed. Knowledge of the population-based prevalence of renal insufficiency in nondiabetic adults would inform such strategies. Black and white nondiabetic adult participants in the Third National Health and Nutrition Examination Survey were analyzed. The analysis was stratified by age, gender, and race, and four clinically applicable methods were used to assess renal function. There were 13,251 complete records for analysis. By the Modification of Diet in Renal Diseases (MDRD) GFR (GFR) prediction Equation 7, 58% (95% confidence interval [CI], 56 to 60%) of the total adult nondiabetic black and white US population had MDRD GFR below 80 ml/min per 1.73m(2), 13% (95% CI, 11 to 14%) below 60 ml/min per 1.73m(2), and 0.26% (95% CI, 0.19 to 0.33%) below 30 ml/min per 1.73m(2). By the Cockcroft-Gault formula, the equivalent figures were 39% (95% CI, 37 to 41%), 14% (95% CI, 12% - 16%), and 0.81% (95% CI, 0.46 to 1.2%), respectively. The findings of an unexpectedly high prevalence of low clearance and the increased prevalence of low clearance with age were consistent across the four clearance estimation methods used and for each race-sex stratum. The absolute magnitude of the prevalence of low clearance was, however, dependent on the clearance method used. Assessed by estimation from serum creatinine, low clearance may be very common, particularly with advancing age. The prognosis (in terms of risk for progression and end-stage renal disease) of low clearance in unreferred populations may differ from that in referred populations and requires further study.

Adult↗

Cumulative risk for developing end-stage renal disease in the US population.

The individual risk of developing end-stage renal disease (ESRD) and its overall impact on life expectancy is not known. This study's objectives were to determine the effect of ESRD on life expectancy for a cohort of 20-yr-olds and to compare this impact to that of several cancers for which population-based screening programs exist. A computer simulation, stratified by race (white, black) and by gender was used to calculate cumulative lifetime risk of ESRD, life-years lost to ESRD, and cumulative Medicare payments for ESRD. Similar calculations were made for breast, prostate, and colorectal cancer. The cumulative lifetime risk of ESRD for a 20-yr-old black woman is 7.8%. Equivalent risks for black men are 7.3%, white men 2.5%, and white women 1.8%. Lost years of life attributable to ESRD are 1.09, 1.10, 0.40, and 0.32 yr for black women, black men, white men, and white women, respectively. In blacks, ESRD is responsible for nearly as much loss of life-years as breast cancer in women and more loss of life-years than colorectal or prostate cancer in men. In addition, treatment costs for ESRD in this population are many-fold more expensive than cumulative treatment costs of these cancers. Exploring new screening and treatment strategies may be warranted to prevent ESRD, particularly in the US black population.

Adult↗

New onset diabetes mellitus post-kidney transplantation.

The study explores the prevalence of unrecognized diabetes mellitus (DM), the incidence and risk factors new onset diabetes mellitus (NODM) and determines whether patient survival differs between patients with transient (NODM that resolves) compared with those with fixed NODM. This is a single center review of solitary kidney recipients transplanted from 1993 to 2003. Of the 381 patients without DM pre-transplant, 111 met criteria for DM post. Of these 17 were unrecognized to have DM, 31 had transient (resolved) NODM and 64 had fixed NODM. In a multivariate analysis, age, body mass index, repeat transplant and rejection were risk factors for NODM. In a separate analysis of only fixed NODM, tacrolimus use showed a trend for an independent association (HR 1.7 95% CI 0.95-2.9). NODM patient survival was comparable to non-diabetic recipients even up to 10 yr; however, excess mortality started to be seen in the fixed NODM subgroup at late follow up. Use of more stringent DM criteria results in a population with relatively good intermediate term survival and allows detection and treatment of early disease. Transient NODM represents approximately one third of NODM and has a relatively good prognosis.

Adult↗