Jennifer M MacRae

The University of Calgary, Calgary, Alberta, Canada

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Publications (52)254.36 Total impact

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    ABSTRACT: Background: Guidelines recommend routine arteriovenous (AV) graft and fistula surveillance (technology-based screening) in addition to clinical monitoring (physical examination) for early identification and pre-emptive correction of a stenosis before the access becomes dysfunctional. However, consequences on patient-relevant outcomes of pre-emptive correction of a stenosis in a functioning access as opposed to deferred correction, i.e. correction postponed to when the access becomes dysfunctional, are uncertain. Objectives: We aimed to evaluate 1) whether pre-emptive correction of an AV access stenosis improves clinically relevant outcomes; 2) whether the effects of pre-emptive correction of an AV access stenosis differ by access type (fistula versus graft), aim (primary and secondary prophylaxis), and surveillance method for primary prophylaxis (Doppler ultrasound for the screening of functional and anatomical changes versus measurement of the flow in the access); and 3) whether other factors (dialysis duration, access location, configuration or materials, algorithm for referral for intervention, intervention strategies (surgical versus radiological or other), or study design) explain the heterogeneity that might exist in the effect estimates. Search methods: We searched the Cochrane Kidney and Transplant Specialised Register to 30 November 2015 using search terms relevant to this review. Selection criteria: We included all studies of any access surveillance method for early identification and pre-emptive treatment of an AV access stenosis. Data collection and analysis: We extracted data on potentially remediable and irremediable failure of the access (i.e. thrombosis and access loss respectively); infection and mortality; and resource use (hospitalisation, diagnostic and intervention procedures). Analysis was by a random effects model and results expressed as risk ratio (RR), hazard ratio (HR) or incidence rate ratio (IRR) with 95% confidence intervals (CI). Main results: We identified 14 studies (1390 participants), nine enrolled adults without a known access stenosis (primary prophylaxis; three studies including people using fistulas) and five enrolled adults with a documented stenosis in a non-dysfunctional access (secondary prophylaxis; three studies in people using fistulas). Study follow-up ranged from 6 to 38 months, and study size ranged from 58 to 189 participants. In low- to moderate-quality evidence (based on GRADE criteria) in adults treated with haemodialysis, relative to no surveillance and deferred correction, surveillance with pre-emptive correction of an AV stenosis reduced the risk of thrombosis (RR 0.79, 95% CI 0.65 to 0.97; I² = 30%; 18 study comparisons, 1212 participants), but had imprecise effect on the risk of access loss (RR 0.81, 95% CI 0.65 to 1.02; I² = 0%; 11 study comparisons, 972 participants). In analyses subgrouped by access type, pre-emptive stenosis correction did not reduce the risk of thrombosis (RR 0.95, 95% CI 0.8 to 1.12; I² = 0%; 11 study comparisons, 697 participants) or access loss in grafts (RR 0.9, 95% CI 0.71 to 1.15; I² = 0%; 7 study comparisons; 662 participants), but did reduce the risk of thrombosis (RR 0.5, 95% CI 0.35 to 0.71; I² = 0%; 7 study comparisons, 515 participants) and the risk of access loss in fistulas (RR 0.5, 95% CI 0.29 to 0.86; I² = 0%; 4 studies; 310 participants). Three of the four studies reporting access loss data in fistulas (199 participants) were conducted in the same centre. Insufficient data were available to assess whether benefits vary by prophylaxis aim in fistulas (i.e. primary and secondary prophylaxis). Although the magnitude of the effects of pre-emptive stenosis correction was considerable for patient-centred outcomes, results were either heterogeneous or imprecise. While pre-emptive stenosis correction may reduce the rates of hospitalisation (IRR 0.54, 95% CI 0.31 to 0.93; I² = 67%; 4 study comparisons, 219 participants) and use of catheters (IRR 0.58, 95% CI 0.35 to 0.98; I² = 53%; 6 study comparisons, 394 participants), it may also increase the rates of diagnostic procedures (IRR 1.78, 95% CI 1.18 to 2.67; I² = 62%; 7 study comparisons, 539 participants), infection (IRR 1.74, 95% CI 0.78 to 3.91; I² = 0%; 3 studies, 248 participants) and mortality (RR 1.38, 95% CI 0.91 to 2.11; I² = 0%; 5 studies, 386 participants).In general, risk of bias was high or unclear in most studies for many domains we assessed. Four studies were published after 2005 and only one had evidence of registration within a trial registry. No study reported information on authorship and/or involvement of the study sponsor in data collection, analysis, and interpretation. Authors' conclusions: Pre-emptive correction of a newly identified or known stenosis in a functional AV access does not improve access longevity. Although pre-emptive stenosis correction may be promising in fistulas existing evidence is insufficient to guide clinical practice and health policy. While pre-emptive stenosis correction may reduce the risk of hospitalisation, this benefit is uncertain whereas there may be a substantial increase (i.e. 80%) in the use of access-related procedures and procedure-related adverse events (e.g. infection, mortality). The net effects of pre-emptive correction on harms and resource use are thus unclear.
    No preview · Article · Jan 2016 · Cochrane database of systematic reviews (Online)
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    ABSTRACT: Background: Preemptive correction of a stenosis in an arteriovenous (AV) access (fistula or graft) that is adequately providing hemodialysis (functional AV access) may prolong access survival as compared to waiting for signs of access dysfunction to intervene (deferred salvage). However, the evidence in support of preemptive intervention is controversial. We evaluated benefits and harms of preemptive versus deferred correction of AV access stenosis. Study design: Systematic review and meta-analysis of randomized controlled trials. Setting & population: Adults receiving hemodialysis by a functional AV access. Selection criteria for studies: We searched the Cochrane Kidney and Transplant Specialised Register and EMBASE to October 15, 2015. Intervention: Active access surveillance (flow measurement and Doppler or venous pressure) and preemptive correction of a newly identified stenosis versus routine clinical monitoring and deferred salvage, or preemptive correction of a known stenosis versus deferred salvage. Outcomes: Access loss (primary outcome) and thrombosis (overall and by access type), infection, mortality, hospitalization, and access-related procedures. Results: We included 14 trials (1,390 participants; follow-up, 6-38 months). Relative to deferred salvage, preemptive correction of AV access stenosis had a nonsignificant effect on risk for access loss (risk ratio [RR], 0.81; 95% CI, 0.65-1.02; I(2)=0%) and a significant effect on risk for thrombosis (RR, 0.79; 95% CI, 0.65-0.97; I(2)=30%). Treatment effects were larger in fistulas than in grafts for both risk for access loss (subgroup difference, P=0.05) and risk for thrombosis (subgroup difference, P=0.002). Results were heterogeneous or imprecise for mortality, rates of access-related infections or procedures, and hospitalization. Limitations: Small number and size of primary studies limited analysis power. Conclusions: Preemptive stenosis correction in a functional AV access does not improve access longevity. Although preemptive stenosis correction may be promising in fistulas, existing evidence is insufficient to guide clinical practice and health policy.
    No preview · Article · Jan 2016 · American Journal of Kidney Diseases
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    ABSTRACT: Unfractionated heparin is the most common anticoagulant used in haemodialysis (HD), although it has many potential adverse effects. Citrate dialysate (CD) has an anticoagulant effect which may allow reduction in cumulative heparin dose (CHD) compared to standard acetate dialysate (AD). This double-blinded, randomised, cross-over trial of chronic haemodialysis patients determines if CD allows reduction in CHD during HD compared with AD. After enrolment, intradialytic heparin is minimised during a two-week run-in period using a standardised protocol based on a visual clotting score. Patients still requiring intradialytic heparin after the run-in period are randomised to two weeks of HD with AD followed by two weeks of CD (Sequence 1) or two weeks of HD with CD followed by two weeks of AD (Sequence 2). The primary outcome is the change in CHD with CD compared with AD. Secondary outcomes include metabolic and haemodynamic parameters, and dialysis adequacy. This randomised controlled trial will determine the impact of CD compared with AD on CHD during HD. NCT01466959.
    Preview · Article · Aug 2015 · BMC Nephrology
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    ABSTRACT: Background Many arteriovenous fistula (AVF) fail prior to use due to lack of maturation or thrombosis. Determining vascular function prior to surgery may be helpful to predict subsequent AVF success. This is a feasibility study to describe the vascular function in a cohort of chronic kidney disease (CKD) patients who are awaiting AVF creation. Methods A prospective cohort of 28 CKD patients expected to progress to HD underwent arterial stiffness (pulse wave velocity, PWV) and endothelial function testing (flow mediated dilation FMD, and peripheral arterial tonometry, PAT) one week prior to AVF creation. AVF success was defined as maintaining patency and achieving maturation. Post operative fistula assessment at 8 weeks evaluated maturation (clinical assessment of adequate fistula flowand ultrasound diameter ≥ 0.5 cm). Results The median age 72 years (62 - 78), 75% males, eGFR 15 ml/min/1.73 m2 (12 – 18). 20 (71%) patients had successful AVF surgery with a mature AVF at 8 weeks. Patients with AVF success had higher mean PAT values 1.87 ± 0.52 than those with failed AVF 1.41 ± 0.24 p = 0.03. Conclusions Microvascular endothelial function as measured using PAT may be useful as a predictor of AVF maturation and function. This simple non invasive marker of vascular function may be a useful tool to predict AVF outcomes.
    Full-text · Article · May 2015
  • Rose Faratro · Janine Jeffries · Gihad E Nesrallah · Jennifer M MacRae
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    ABSTRACT: Creating and maintaining a healthy vascular access is a critical factor in successful home hemodialysis (HD). This article aims to serve as a "how-to manual" regarding vascular access issues for both patients and health-care providers in a home HD program. This document outlines cannulation options for patients with arteriovenous access and describes troubleshooting techniques for potential complications; strategies are suggested to help patients overcome fear of cannulation and address problems associated with difficult cannulation. Technical aspects of central venous catheter care, as well as a guide to troubleshooting catheter complications, are covered in detail. Monitoring for access-related complications of stenosis, infection, and thrombosis is a key part of every home HD program. Key performance and quality indicators are important mechanisms to ensure patient safety in home HD and should be used during routine clinic visits. © 2015 International Society for Hemodialysis.
    No preview · Article · Apr 2015 · Hemodialysis International
  • Kristen Parker · Xin Zhang · Adriane Lewin · Jennifer M MacRae
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    ABSTRACT: Hemodialysis (HD) patients have high hospitalization rates. Benefits of intradialytic exercise have been proven in numerous studies yet exercise programs are still rarely used in the treatment of end-stage kidney disease (ESKD). Our objective was to determine if there was an association between a 6-month intradialytic bicycling program and hospitalization rates and length of stay (LOS) in ESKD patients. This was a retrospective cohort study that took place 6 months prior to and 6 months during an intradialtyic exercise program at an outpatient HD unit in Calgary, Alberta, Canada. Participants comprised 102 patients who had commenced HD <6 months (incident) or >6 months (prevalent) prior to starting exercise. The intervention comprised a 6-month intradialytic bicycling program. Main outcome measures were hospitalization rate, cause of hospitalization, and LOS. Patients were predominantly male (67.6%) aged 65.6 ± 13.5 years and median HD vintage 1 year (range: 0-12). Comorbidities included diabetes mellitus (50%) and cardiac disease (38.2%). The hospitalization incidence rate ratio (IRR) was 0.48 (0.23-0.98; P = 0.04) in incident and 0.89 (0.56-1.42; P = 0.64) in prevalent patients. The LOS decreased from 7.8 (95% confidence interval (CI): 7.3-8.4) to 3.1 (95% CI: 2.8-3.4) days and LOS IRR was 0.39 (0.35-0.45; P < 0.001). The main predictors of hospitalization were lower albumin levels (P = 0.007) and lack of intradialytic exercise program participation (P < 0.001). In conclusion, 6 months of intradialytic exercise was associated with decreased LOS in both incident and prevalent HD patients.
    No preview · Article · Apr 2015 · Applied Physiology Nutrition and Metabolism
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    Kelvin Cw Leung · Robert R Quinn · Pietro Ravani · Jennifer M MacRae
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    ABSTRACT: Fluid removal during dialysis, also known as ultrafiltration (UF), leads to intradialytic hypotension (IDH) in a significant number of patients treated with hemodialysis (HD) and is associated with an increase in morbidity and mortality. At present, there are no accepted standards of practice for the prevention or treatment of IDH. Relative blood volume monitoring (BVM) is based on the concept that the hematocrit increases with UF, relative to the patient's baseline hematocrit. The use of BVM biofeedback, whereby the HD machine automatically adjusts the rate of UF based on the relative blood volume, has been proposed for the prevention of IDH. This is a 22-week randomized crossover trial. Participants undergo a 4-week run-in phase to standardize medications and dialysis prescriptions. Subsequently, participants are randomized to standard HD or to BVM biofeedback for a period of 8 weeks followed by a 2-week washout phase before crossing over. The dialysis prescription remains identical for both arms. The primary outcome is the frequency of symptomatic IDH as defined by an abrupt drop in the systolic blood pressure of >=20 mm Hg accompanied by headache, dizziness, loss of consciousness, thirst, dyspnea, angina, muscle cramps or vomiting. Secondary outcomes include the number of symptomatic IDH episodes and any reduction in IDH episodes, nursing interventions, dialysis adequacy, total body water, extra- and intracellular fluid volumes, brain natriuretic peptide and cardiac troponin levels, blood pressure, antihypertensive medication use, patient symptoms and quality of life. Our study will determine the impact of using BVM biofeedback to prevent IDH and other serious adverse events in susceptible patients.Trial registration: NCT01988181 (6 November 2013).
    Preview · Article · Dec 2014 · Trials
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    ABSTRACT: Uric acid is associated with hypertension and increased renin–angiotensin system activity, although this relationship diminishes after chronic exposure to high levels. Uric acid is more strongly associated with poor outcomes in women compared to men, although whether this is due to a sex-specific uric acid-mediated pathophysiology or reflects sex differences in baseline uric acid levels remains unknown. We examined the association between uric acid and vascular measures at baseline and in response to angiotensin-II challenge in young healthy humans. Fifty-two subjects (17 men, 35 premenopausal women) were studied in high-salt balance. Serum uric acid levels were significantly higher in men compared to women (328 ± 14 μmol/L vs. 248 ± 10 μmol/L, P < 0.001), although all values were within normal sex-specific range. Men demonstrated no association between uric acid and blood pressure, either at baseline or in response to angiotensin-II. In stark contrast, a significant association was observed between uric acid and blood pressure at baseline (systolic blood pressure, P = 0.005; diastolic blood pressure, P = 0.02) and in response to angiotensin-II (systolic blood pressure, P = 0.035; diastolic blood pressure, P = 0.056) in women. However, this sex difference lost significance after adjustment for baseline uric acid. When all subjects were stratified according to high (>300 μmol/L) or low (≤300 μmol/L) uric acid levels, only the low uric acid group showed a positive association between uric acid and measures of vascular tone at baseline and in response to angiotensin-II. Differences in uric acid-mediated outcomes between men and women likely reflect differences in exposure to increased uric acid levels, rather than a sex-specific uric acid-mediated pathophysiology.
    Preview · Article · Dec 2014
  • Jennifer M MacRae

    No preview · Article · Oct 2014 · American Journal of Kidney Diseases
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    Robert J H Miller · Jennifer M MacRae · Stefan Mustata
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    ABSTRACT: Background: Arteriovenous fistula is an uncommon complication of central venous catheterization that often requires invasive repair. Case report: We report the case of an arteriovenous fistula that presented as ongoing pain following removal of a tunneled central venous catheter. The fistula resolved spontaneously following a period of compression and observation. Conclusion: Our study highlights the etiology of this uncommon complication as well as suggesting a role for conservative management.
    Preview · Article · Sep 2014
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    ABSTRACT: Background Patients with end-stage kidney disease (ESKD) have a high rate of mortality and specifically an increased risk of sudden cardiac death (SCD). Impaired cardiac autonomic tone is associated with elevated risk of SCD. Moreover, patients with ESKD are often vitamin D deficient, which we have shown may be linked to autonomic dysfunction in humans. To date, it is not known whether vitamin D supplementation normalizes cardiac autonomic function in the high-risk ESKD population. The VITamin D supplementation and cardiac Autonomic tone in Hemodialysis (VITAH) randomized trial will determine whether intensive vitamin D supplementation therapies improve cardiac autonomic tone to a greater extent than conventional vitamin D supplementation regimens in ESKD patients requiring chronic hemodialysis. Methods/Design A total of 60 subjects with ESKD requiring thrice weekly chronic hemodialysis will be enrolled in this 2x2 crossover, blinded, randomized controlled trial. Following a 4-week washout period from any prior vitamin D therapy, subjects are randomized 1:1 to intensive versus standard vitamin D therapy for 6 weeks, followed by a 12-week washout period, and finally the remaining treatment arm for 6 weeks. Intensive vitamin D treatment includes alfacalcidiol (activated vitamin D) 0.25mcg orally with each dialysis session combined with ergocalciferol (nutritional vitamin D) 50 000 IU orally once per week and placebo the remaining two dialysis days for 6 weeks. The standard vitamin D treatment includes alfacalcidiol 0.25mcg orally combined with placebo each dialysis session per week for 6 weeks. Cardiac autonomic tone is measured via 24 h Holter monitor assessments on the first dialysis day of the week every 6 weeks throughout the study period. The primary outcome is change in the low frequency: high frequency heart rate variability (HRV) ratio during the first 12 h of the Holter recording at 6 weeks versus baseline. Secondary outcomes include additional measures of HRV. The safety of intensive versus conventional vitamin D supplementation is also assessed. Discussion VITAH will determine whether an intensive vitamin D supplementation regimen will improve cardiac autonomic tone compared to conventional vitamin D supplementation and will assess the safety of these two supplementation regimens in ESKD patients receiving chronic hemodialysis. Trial registration, NCT01774812
    Full-text · Article · Aug 2014 · BMC Nephrology
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    ABSTRACT: We previously reported a reduction in central venous catheter (CVC) malfunction when using once-weekly recombinant tissue-plasminogen activator (rt-PA) as a locking solution, compared with thrice-weekly heparin. To identify risk factors for CVC malfunction to inform a targeted strategy for rt-PA use. Retrospective analysis. Canadian hemodialysis (HD) units. Adults with newly placed tunnelled upper venous system CVCs randomized to a locking solution of rt-PA(1 mg/mL) mid-week and heparin (5000 u/ml) on the other HD sessions, or thrice-weekly heparin (5000 u/ml). CVC malfunction (the primary outcome) was defined as: peak blood flow less than 200 mL/min for thirty minutes during a HD session; mean blood flow less than 250 mL/min for two consecutive HD sessions; inability to initiate HD. Cox regression was used to determine the association between patient demographics, HD session CVC-related variables and the outcome of CVC malfunction. Patient age (62.4 vs 65.4 yr), proportion female sex (35.6 vs 48.4%), and proportion with first catheter ever (60.7 vs 61.3%) were similar between patients with and without CVC malfunction. After multivariate analysis, risk factors for CVC malfunction were mean blood processed < 65 L when compared with ≥ 85 L in the prior 6 HD sessions (HR 4.36; 95% CI, 1.59 to 11.95), and mean blood flow < 300 mL/min, or 300 - 324 mL/min in the prior 6 HD sessions (HR 7.65; 95% CI, 2.78 to 21.01, and HR 5.52; 95% CI, 2.00 to 15.23, respectively) when compared to ≥ 350 mL/min. This pre-specified post-hoc analysis used a definition of CVC malfunction that included blood flow, which may result in an overestimate of the effect size. Generalizability of results to HD units where trisodium citrate locking solution is used may also be limited. HD session characteristics including mean blood processed and mean blood flow were associated with CVC malfunction, while patient characteristics were not. Whether targeting these patients at greater risk of CVC malfunction with rt-PA as a locking solution improves CVC longevity remains to be determined.
    Preview · Article · Jul 2014
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    ABSTRACT: Over 40% of patients with end stage renal disease in the United States were treated with home hemodialysis (HHD) in the early 1970's. However, this number declined rapidly over the ensuing decades so that the overwhelming majority of patients were treated in-centre 3 times per week on a 3-4 hour schedule. Poor outcomes for patients treated in this fashion led to a renewed interest in home hemodialysis, with more intensive dialysis schedules including short daily (SDHD) and nocturnal (NHD). The relative infancy of these treatment schedules means that there is a paucity of data on 'how to do it'. We undertook a systematic survey of home hemodialysis programs in Canada to describe current practice patterns. Development and deployment of a qualitative survey instrument. Community and academic HHD programs in Canada. Physicians, nurses and technologists. Programmatic approaches to patient selection, delivery of dialysis, human resources available, and follow up. We developed the survey instrument in three phases. A focus group of Canadian nephrologists with expertise in NHD or SDHD discussed the scope the study and wrote questions on 11 domains. Three nephrologists familiar with all aspects of HHD delivery reviewed this for content validity, followed by further feedback from the whole group. Multidisciplinary teams at three sites pretested the survey and further suggestions were incorporated. In July 2010 we distributed the survey electronically to all renal programs known to offer HHD according to the Canadian Organ Replacement Registry. We compiled the survey results using qualitative and quantitative methods, as appropriate. Of the academic and community programs that were invited to participate, 80% and 63%, respectively, completed the survey. We observed wide variation in programmatic approaches to patient recruitment, human resources, equipment, water, vascular access, patient training, dialysis prescription, home requirements, patient follow up, medications, and the approach to non-adherent patients. Cross-sectional survey, unable to link variation to outcomes. Competition for patients between HHD and home peritoneal dialysis means that case mix for HHD may also vary between centres. There is wide variation between programs in all domains of HHD delivery in Canada. We plan further study of the extent to which differences in approach are related to outcomes.
    No preview · Article · Jun 2014
  • Jennifer M. MacRae · Sofia B. Ahmed · Brenda R. Hemmelgarn
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    ABSTRACT: Background We previously have shown that buttonhole needling is associated with a reduction in hematoma and postulated that buttonhole needling may increase long-term survival of an arteriovenous fistula (AVF). The purpose of this study was to evaluate AVF survival and complications in buttonhole versus standard needling. Study Design Long-term follow up of a randomized controlled trial in which participants were randomly assigned to standard or buttonhole needling and followed up until the AVF was abandoned or the study end date. Setting & Participants 140 long-term hemodialysis patients in Calgary, Alberta. Intervention Buttonhole needling with median time of exposure to the intervention of 13.2 (IQR, 7.8-19.4) months. Outcomes & Measurements Patients were prospectively followed up for study outcomes. Median follow-up times were 17.2 (IQR, 11.9-37.8) and 19.2 (IQR, 12.5-41.0) months for standard and buttonhole needling, respectively (P = 0.2). The primary outcome was median access survival in months. Other outcomes included assisted and unassisted patency rates, rates of surgical and radiologic interventions, and time to abandonment (months) of buttonhole. Results Baseline characteristics were similar. The primary outcome, median access survival, was similar in both groups: 16.0 (IQR, 10.6-29.3) and 18.4 (IQR, 10.9-32.7) months for standard and buttonhole needling, respectively (P = 0.2). There were 7 (10.1%) and 6 (8.6%) thromboses with standard and buttonhole needling, respectively (P = 0.6). Median fistulogram rates were similar between techniques (P = 0.2 with intention-to-treat analysis). Most patients (46 of 70) abandoned buttonhole needling by a median of 11.3 (IQR, 4.8-18.2) months. Median time to first infection for buttonhole needling was 11.1 (IQR, 4.9-30.0) months. There were no infections in standard needling of AVFs. Limitations Findings are limited to patients needled by multiple hemodialysis nurses and not applicable to self-needlers. Conclusions AVFs with buttonhole needling did not have improved survival. The lack of survival benefit and higher risk of infection should be noted when promoting buttonhole needling.
    No preview · Article · Apr 2014 · American Journal of Kidney Diseases
  • Jennifer M Macrae · Michael Copland · Mercedeh Kiaii

    No preview · Article · Mar 2014 · Seminars in Dialysis
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    ABSTRACT: Objective: Sex influences the cardiorenal risk associated with body mass index (BMI). The role of the renin-angiotensin-aldosterone system in adiposity-mediated cardiorenal risk profiles in healthy, non-obese men and women was investigated. Methods: Systemic and renal hemodynamic responses to angiotensin-II (AngII) as a function of BMI, waist and hip circumference, waist-hip ratio, as well as fat and lean mass were measured in 18 men and 25 women in high-salt balance, stratified by BMI (<25 kg/m2 (ideal body weight (IBW)) vs. ≥25 kg/m2 overweight)). Results: In men (n = 7, BMI 23 ± 1 kg/m2) and women (n = 14, BMI 22 ± 2 kg/m2) of IBW, BMI was not associated with the systolic blood pressure (SBP) response to AngII. In contrast, overweight men (n = 11, 29 ± 2 kg/m2) demonstrated a progressively more blunted vasoconstrictor SBP response to AngII challenge as BMI increased (P = 0.007), even after adjustment for covariates. Women maintained the same relationship between BMI and the SBP response to AngII irrespective of weight status (P = 0.2, IBW vs. overweight women). Compared to BMI, other adiposity measures showed similar associations to systemic AngII responsiveness in men but not in women. Increasing BMI was associated with a blunted renovasoconstrictor response to AngII in all subjects, but was more pronounced in men. Conclusion: Sex influences the effect of adiposity on vascular angiotensin-responsiveness.
    No preview · Article · Mar 2014 · Obesity
  • Jennifer M Macrae · Sofia B Ahmed · Brenda R Hemmelgarn

    No preview · Article · Jan 2014 · American Journal of Kidney Diseases
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    ABSTRACT: Abstract Vitamin D deficiency is associated with increased arterial stiffness. We sought to clarify the influence of vitamin D in modulating angiotensin II-dependent arterial stiffness. Thirty-six healthy subjects (33 ± 2 years, 67% female, mean 25-hydroxyvitamin D 69 ± 4 nmol/L) were studied in high salt balance. Arterial stiffness, expressed as brachial pulse wave velocity (bPWV) and aortic augmentation index (AIx), was measured by tonometry at baseline and in response to angiotensin II infusion (3 ng/kg/min × 30 min then 6 ng/kg/min × 30 min). The primary outcome was change in bPWV after an angiotensin II challenge. Results were analyzed according to plasma 25-hydroxyvitamin D status: deficient (<50 nmol/L) and sufficient (≥50 nmol/L). There were no differences in baseline arterial stiffness between vitamin D deficient (25-hydroxyvitamin D 40 ± 2 nmol/L) and sufficient (25-hydroxyvitamin D 80 ± 4 nmol/L) groups. Compared with sufficient vitamin D status, vitamin D deficiency was associated with a decreased arterial response to angiotensin II challenge (Δbrachial pulse wave velocity: 0.48 ± 0.44 m/s versus 1.95 ± 0.22 m/s, p = 0.004; Δaortic augmentation index: 9.4 ± 3.4% versus 14.2 ± 2.7%, p = 0.3), which persisted for brachial pulse wave velocity response after adjustment for covariates (p = 0.03). Vitamin D deficiency is associated with increased arterial stiffness in healthy humans, possibly through an angiotensin II-dependent mechanism.
    No preview · Article · Oct 2013 · Clinical and Experimental Hypertension
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    Rajneet K Atkar · Jennifer M Macrae
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    ABSTRACT: There has been increased interest in buttonhole cannulation, particularly in the last 5 years, because of the perceived benefit of improved fistula outcomes. The recent randomized trials provide for a timely review regarding the potential benefit and possible harms of the buttonhole technique. The majority of observational studies report a reduction in pain with buttonhole; however, after reviewing the results from five randomized trials, buttonhole cannulation, when delivered by a nurse, does not appear to be less painful than rope ladder cannulation. Studies consistently report fewer infiltrations, reduced hematoma and a reduction of aneurysm formation with buttonhole. These benefits must be balanced against the increased risk of infection and septic complications seen with buttonhole cannulation. On the basis of the current studies, buttonhole, when done in an in-center environment with many rotating staff nurses, is a complex and challenging technique. Buttonhole technique might be best utilized for difficult or limited fistula needling sites. An infection prevention education campaign along with regular audits regarding localized infections and bacteremias should be a critical part of any program which uses buttonhole cannulation. A randomized trial comparing buttonhole to rope ladder needling among home hemodialysis or self-needled patients should be the focus for future research.
    Full-text · Article · Sep 2013 · Current Opinion in Nephrology and Hypertension
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    ABSTRACT: Vascular access complications are a major cause of morbidity in patients undergoing hemodialysis, and determining how the risks of different complications vary over the life of an access may benefit the design of prevention strategies. We used data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) to assess the temporal profiles of risks for infectious and noninfectious complications of fistulas, grafts, and tunneled catheters in incident hemodialysis patients. We used longitudinal data to model time from access placement or successful treatment of a previous complication to subsequent complication and considered multiple accesses per patient and repeated access complications using baseline and time-varying covariates to obtain adjusted estimates. Of the 7769 incident patients identified, 7140 received at least one permanent access. During a median follow-up of 14 months (interquartile range, 7-22 months), 10,452 noninfectious and 1131 infectious events (including 551 hospitalizations for sepsis) occurred in 112,085 patient-months. The hazards for both complication types declined over time in all access types: They were 5-10 times greater in the first 3-6 months than in later periods after access placement or a remedial access-related procedure. The hazards declined more quickly with fistulas than with grafts and catheters (P<0.001; Weibull regression). These data indicate that risks for noninfectious and infectious complications of the hemodialysis access decline over time with all access types and suggest that prevention strategies should target the first 6 months after access placement or a remedial access-related procedure.
    Preview · Article · Jul 2013 · Journal of the American Society of Nephrology

Publication Stats

909 Citations
254.36 Total Impact Points


  • 2006-2016
    • The University of Calgary
      • • Department of Medicine
      • • Division of Neurology
      • • Department of Cardiac Sciences
      Calgary, Alberta, Canada
  • 2004-2006
    • University of British Columbia - Vancouver
      • Division of Nephrology
      Vancouver, British Columbia, Canada