Chandra Thomas

Associations between Hemodialysis Access Type and Clinical Outcomes: A Systematic Review

Clinical practice guidelines recommend an arteriovenous fistula as the preferred vascular access for hemodialysis, but quantitative associations between vascular access type and various clinical outcomes remain controversial. We performed a systematic review of cohort studies to evaluate the associations between type of vascular access (arteriovenous fistula, arteriovenous graft, and central venous catheter) and risk for death, infection, and major cardiovascular events. We searched MEDLINE, EMBASE, and article reference lists and extracted data describing study design, participants, vascular access type, clinical outcomes, and risk for bias. We identified 3965 citations, of which 67 (62 cohort studies comprising 586,337 participants) met our inclusion criteria. In a random effects meta-analysis, compared with persons with fistulas, those individuals using catheters had higher risks for all-cause mortality (risk ratio=1.53, 95% CI=1.41-1.67), fatal infections (2.12, 1.79-2.52), and cardiovascular events (1.38, 1.24-1.54). Similarly, compared with persons with grafts, those individuals using catheters had higher risks for mortality (1.38, 1.25-1.52), fatal infections (1.49, 1.15-1.93), and cardiovascular events (1.26, 1.11-1.43). Compared with persons with fistulas, those individuals with grafts had increased all-cause mortality (1.18, 1.09-1.27) and fatal infection (1.36, 1.17-1.58), but we did not detect a difference in the risk for cardiovascular events (1.07, 0.95-1.21). The risk for bias, especially selection bias, was high. In conclusion, persons using catheters for hemodialysis seem to have the highest risks for death, infections, and cardiovascular events compared with other vascular access types, and patients with usable fistulas have the lowest risk.

Systematic Review of the Risk of Adverse Outcomes Associated with Vascular Endothelial Growth Factor Inhibitors for the Treatment of Cancer

Background Anti-angiogenic therapy targeted at vascular endothelial growth factor (VEGF) is now used to treat several types of cancer. We did a systematic review of randomized controlled trials (RCTs) to summarize the adverse effects of vascular endothelial growth factor inhibitors (VEGFi), focusing on those with vascular pathogenesis. Methods and Findings We searched MEDLINE, EMBASE and Cochrane Library until April 19, 2012 to identify parallel RCTs comparing a VEGFi with a control among adults with any cancer. We pooled the risk of mortality, vascular events (myocardial infarction, stroke, heart failure, and thromboembolism), hypertension and new proteinuria using random-effects models and calculated unadjusted relative risk (RR). We also did meta-regression and assessed publication bias. We retrieved 83 comparisons from 72 studies (n = 38,078) on 11 different VEGFi from 7901 identified citations. The risk of mortality was significantly lower among VEGFi recipients than controls (pooled RR 0.96, 95% confidence interval [CI] 0.94 to 0.98, I2 = 0%, tau2 = 0; risk difference 2%). Compared to controls, VEGFi recipients had significantly higher risk of myocardial infarction (MI) (RR 3.54, 95% CI 1.61 to 7.80, I2 = 0%, tau2 = 0), arterial thrombotic events (RR 1.80, 95% CI 1.24 to 2.59, I2 = 0%, tau2 = 0); hypertension (RR 3.46, 95% CI 2.89 to 4.15, I2 = 58%, tau2 = 0.16), and new proteinuria (RR 2.51, 95% CI 1.60 to 3.94, I2 = 87%, tau2 = 0.65). The absolute risk difference was 0.8% for MI, 1% for arterial thrombotic events, 15% for hypertension and 12% for new proteinuria. Meta-regression did not suggest any statistically significant modifiers of the association between VEGFi treatment and any of the vascular events. Limitations include heterogeneity across the trials. Conclusions VEGFi increases the risk of MI, hypertension, arterial thromboembolism and proteinuria. The absolute magnitude of the excess risk appears clinically relevant, as the number needed to harm ranges from 7 to 125. These adverse events must be weighed against the lower mortality associated with VEGFi treatment.

Concentration of heparin-locking solution and risk of central venous hemodialysis catheter malfunction.

Heparin is used as an interdialytic locking solution for hemodialysis (HD) central venous catheters (CVCs). The purpose of this study was to compare effectiveness of two heparin concentrations (10,000 and 1,000 U/mL) in preventing catheter malfunction. We compared two time periods: a 6-month period with heparin 10,000 U/mL and a 3-month period with heparin 1,000 U/mL. Adults on HD using a CVC (tunneled or untunneled) in Calgary, Alberta, were included. The primary outcome was catheter malfunction. A total of 139 and 134 patients in the heparin 10,000 and 1,000 U/mL periods, respectively, were included. The crude rate of catheter malfunction, per 1,000 HD sessions, was similar for heparin 10,000 (7.6; 95% CI, 5.3 to 10.8) and 1,000 (6.7; 95% CI, 4.3 to 10.3) U/mL periods, respectively (p = 0.76). After adjusting for CVC characteristics and use of recombinant tissue plasminogen activator (rt-PA), there was no association between heparin concentration and CVC malfunction (hazard ratio, 0.77; 95% CI, 0.37 to 1.61). In conclusion, the use of a lower concentration of heparin was not associated with an increased risk of catheter malfunction but may be associated with greater rt-PA use. The association between heparin concentration and rt-PA use requires further study.

Improving rates of pneumococcal vaccination on discharge from a tertiary center medical teaching unit: A prospective intervention

BackgroundPneumococcal disease causes significant morbidity and mortality in at-risk individuals, and is complicated by emerging antibiotic resistance. An effective, safe and cost-effective vaccine is available, but despite this many patients who would benefit from pneumococcal vaccination remain unvaccinated. The purpose of this study was to determine the rates of missed opportunities to provide pneumococcal vaccination to patients being discharged from a tertiary center medical teaching unit and to determine if a nurse coordinator-based intervention would increase rates of pneumococcal vaccination prior to discharge home.MethodsWe conducted a prospective, controlled study in the setting of a Medical Teaching Unit at a tertiary care centre to assess the impact of a nurse coordinator based intervention on the rates of vaccination of eligible patients on discharge home. The rates of vaccination during an eight-week usual-care period (February 20 to April 16, 2002) and an eight-week intervention period (April 22 to June 16, 2002) were compared.ResultsPrior to the intervention none of thirty-eight eligible patients were vaccinated prior to discharge home from the Medical Teaching Unit. After the intervention 27 (54%) of fifty eligible patients were vaccinated prior to discharge.ConclusionThere are significant missed opportunities to provide pneumococcal vaccination to inpatients who are discharged home from a medical unit. Using a patient care coordinator we were able to significantly improve the rates of vaccination on discharge.

Does the Evidence Support Conservative Management as an Alternative to Dialysis for Older Patients with Advanced Kidney Disease

There is ongoing debate whether older adult patients with stage 5 CKD gain survival advantage when treated with dialysis compared with conservative management. Comprehensive conservative management that is chosen or medically advised ([1][1]) focuses on optimizing quality of life and is recommended

Emergency Department Use among Patients with CKD: A Population-Based Analysis

BACKGROUND AND OBJECTIVES Although prior studies have observed high resource use among patients with CKD, there is limited exploration of emergency department use in this population and the proportion of encounters related to CKD care specifically. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We identified all adults (≥18 years old) with eGFR<60 ml/min per 1.73 m2 (including dialysis-dependent patients) in Alberta, Canada between April 1, 2010 and March 31, 2011. Patients with CKD were linked to administrative data to capture clinical characteristics and frequency of emergency department encounters and followed until death or end of study (March 31, 2013). Within each CKD category, we calculated adjusted rates of overall emergency department use as well as rates of potentially preventable emergency department encounters (defined by four CKD-specific ambulatory care-sensitive conditions: heart failure, hyperkalemia, volume overload, and malignant hypertension). RESULTS During mean follow-up of 2.4 years, 111,087 patients had 294,113 emergency department encounters; 64.2% of patients had category G3A CKD, and 1.6% were dialysis dependent. Adjusted rates of overall emergency department use were highest among patients with more advanced CKD; 5.8% of all emergency department encounters were for CKD-specific ambulatory care-sensitive conditions, with approximately one third resulting in hospital admission. Heart failure accounted for over 80% of all potentially preventable emergency department events among patients with categories G3A, G3B, and G4 CKD, whereas hyperkalemia accounted for almost one half (48%) of all ambulatory care-sensitive conditions among patients on dialysis. Adjusted rates of emergency department events for heart failure showed a U-shaped relationship, with the highest rates among patients with category G4 CKD. In contrast, there was a graded association between rates of emergency department use for hyperkalemia and CKD category. CONCLUSIONS Emergency department use is high among patients with CKD, although only a small proportion of these encounters is for potentially preventable CKD-related care. Strategies to reduce emergency department use among patients with CKD will, therefore, need to target conditions other than CKD-specific ambulatory care-sensitive conditions.

Validity of ICD-9-CM administrative data for determining eligibility for pneumococcal vaccination triggers.

The purpose of this study was to evaluate the efficacy of medical record administrative data as coded by the International Classification of Diseases, Ninth Revision, for triggering pneumococcal vaccination reminders of patients following discharge from a tertiary care adult teaching hospital. A retrospective computerized search was conducted using administrative discharge data to detect patients admitted to the medical teaching unit who met clinical criteria for pneumococcal vaccination according to Canadian immunization guidelines. For identification of persons eligible for vaccination, administrative discharge data showed a sensitivity of 83% (confidence interval [CI], 0.73-0.92) and a specificity of 78% (CI, 0.64-0.91), with a positive predictive value of 87% (CI, 0.83-0.90) and a negative predictive value of 72% (CI, 0.58-0.86). The reasonably high specificity and sensitivity of diagnostic codes in administrative data could be used to trigger appropriate pneumococcal vaccination among eligible patients after hospital discharge.

Primary care physicians’ perceived barriers and facilitators to conservative care for older adults with chronic kidney disease: design of a mixed methods study

BackgroundGuideline committees have identified the need for research to inform the provision of conservative care for older adults with stage 5 chronic kidney disease (CKD) who have a high burden of comorbidity or functional impairment. We will use both qualitative and quantitative methodologies to provide a comprehensive understanding of barriers and facilitators to care for these patients in primary care.ObjectivesOur objectives are to (1) interview primary care physicians to determine their perspectives of conservative care for older adults with stage 5 CKD and (2) survey primary care physicians to determine the prevalence of key barriers and facilitators to provision of conservative care for older adults with stage 5 CKD.DesignA sequential exploratory mixed methods design was adopted for this study. The first phase of the study will involve fundamental qualitative description and the second phase will be a cross-sectional population-based survey.SettingThe research is conducted in Alberta, Canada.ParticipantsThe participants are primary care physicians with experience in providing care for older adults with stage 5 CKD not planning on initiating dialysis.MethodsThe first objective will be achieved by undertaking interviews with primary care physicians from southern Alberta. Participants will be selected purposively to include physicians with a range of characteristics (e.g., age, gender, and location of clinical practice). Interviews will be recorded, transcribed verbatim, and analyzed using conventional content analysis to generate themes. The second objective will be achieved by undertaking a population-based survey of primary care physicians in Alberta. The questionnaire will be developed based on the findings from the qualitative interviews and pilot tested for face and content validity. Physicians will be provided multiple options to complete the questionnaire including mail, fax, and online methods. Descriptive statistics and associations between demographic factors and barriers and facilitators to care will be analyzed using regression models.LimitationsA potential limitation of this mixed methods study is its cross-sectional nature.ConclusionsThis work will inform development of clinical resources and tools for care of older adults with stage 5 CKD, to address barriers and enable facilitators to community-based conservative care.ABRÉGÉMise en contexteLes comités pour l’établissement de lignes directrices ont relevé la nécessité pour la recherche de faciliter la mise en place d’un traitement conservateur chez les adultes âgés atteints d’insuffisance rénale chronique (IRC) de stade 5, des patients présentant une incidence élevée de comorbidité et d’altération de la fonction rénale. Des méthodes qualitatives et quantitatives seront utilisées pour assurer une compréhension détaillée des obstacles aux soins de première ligne et en contrepartie, des éléments qui les facilitent.Objectifs de l’étudeCette étude vise deux objectifs principaux :1) Interroger les médecins qui prodiguent des soins primaires afin de connaître leur point de vue sur l’administration d’un traitement conservateur chez les patients âgés atteints d’IRC de stade 5.2) Sonder ces mêmes médecins pour établir la prévalence tant des obstacles à fournir des traitements conservateurs que des éléments la facilitant chez les patients âgés atteints d’IRC de stade 5.Cadre et type d’étudeIl s’agit d’un modèle d’étude exploratoire à méthodes mixtes qui sera effectuée de façon séquentielle. Une première phase impliquera une description qualitative fondamentale tandis qu’une deuxième consistera en une enquête transversale menée dans la population. Les deux phases de l’étude se tiendront en Alberta, au Canada.ParticipantsUn groupe de médecins prodiguant des soins primaires à des patients âgés atteints d’IRC de stade 5, mais n’envisageant pas de commencer des traitements d’hémodialyse.MéthodologieLe premier objectif sera atteint en menant une enquête auprès des médecins du sud de l’Alberta prodiguant des soins de première ligne. Les participants seront sélectionnés avec l’intention d’inclure des praticiens représentant un éventail de caractéristiques (âge, genre, lieu de pratique). Les entrevues seront enregistrées puis transcrites intégralement, et l’information recueillie sera traitée en utilisant une approche conventionnelle d’analyse du contenu pour en tirer les thématiques. Le second objectif sera également réalisé en procédant à une enquête dans la population de médecins prodiguant des soins de première ligne en Alberta. Le questionnaire sera mis au point suivant les résultats obtenus lors des entretiens qualificatifs et testés lors d’essais-pilotes visant à établir leur validité apparente et de contenu. Les praticiens disposeront de plusieurs moyens pour retourner le questionnaire une fois complété soit par la poste, par fax ou par d’autres méthodes en ligne. Les données statistiques descriptives ainsi que les associations établies entre les facteurs démographiques et les obstacles et facilitateurs de soins seront analysées à l’aide de modèles de régression.Limites de l’étudeNous prévoyons une éventuelle limite à cette étude par méthodes mixtes compte tenu de sa nature transversale.ConclusionsÀ terme, ces travaux orienteront le développement de ressources cliniques et d’outils pour la prise en charge des patients âgés atteints d’IRC de stade 5. Ils contribueront également à rendre possible l’établissement de programmes de traitements conservateurs communautaires et à éliminer les obstacles rencontrés.

Using intelligent agents to repurpose administrative data in fostering disease prevention in an outpatient context: the case of pneumococcal vaccination

The use of intelligent agents is proposed as an economical way to repurpose administrative data in order to foster a program of disease prevention in an outpatient context. A retrospective computerized search was conducted using administrative hospital discharge data to identify patients admitted to a medical teaching unit who met the Canadian Immunization criteria for pneumococcal vaccination over a one-year period. For identification of persons eligible for pneumococcal vaccination, administrative discharge data was shown to have a sensitivity of 83%, (confidence interval [CI] 0.73-0.92) and a specificity of 78% CI (0.64-0.91), with a positive predictive value [PPV] of 87%, CI (0.83- 0.90) and a negative predictive value [NPV] of 72%, CI (0.58-0.86). This study demonstrates that administrative data appear promising as the basis for certain clinical applications. Specifically, the reasonably high specificity and sensitivity of diagnostic codes in administrative data could be utilized to trigger appropriate pneumococcal vaccination after hospital discharge among eligible patients who might otherwise never receive this efficacious intervention. Reminder systems in a hospital setting have received mixed results although positive results have been shown in several outpatient settings but using clinical data. Therefore, before a reminder system using administrative data in an outpatient context is implemented it seemed prudent to investigate this issue further.

Survival among older adults with kidney failure is better in the first three years with chronic dialysis treatment than not

Comparisons of survival between dialysis and nondialysis care for older adults with kidney failure have been limited to those managed by nephrologists, and are vulnerable to lead and immortal time biases. So we compared time to all-cause mortality among older adults with kidney failure treated vs. not treated with chronic dialysis. Our retrospective cohort study used linked administrative and laboratory data to identify adults aged 65 or more years of age in Alberta, Canada, with kidney failure (2002-2012), defined by two or more consecutive outpatient estimated glomerular filtration rates less than 10 mL/min/1.73m2, spanning 90 or more days. We used marginal structural Cox models to assess the association between receipt of dialysis and all-cause mortality by allowing control for both time-varying and baseline confounders. Overall, 838 patients met inclusion criteria (mean age 79.1; 48.6% male; mean estimated glomerular filtration rate 7.8 mL/min/1.73m2). Dialysis treatment (vs. no dialysis) was associated with a significantly lower risk of death for the first three years of follow-up (hazard ratio 0.59 [95% confidence interval 0.46-0.77]), but not thereafter (1.22 [0.69-2.17]). However, dialysis was associated with a significantly higher risk of hospitalization (1.40 [1.16-1.69]). Thus, among older adults with kidney failure, treatment with dialysis was associated with longer survival up to three years after reaching kidney failure, though with a higher risk of hospital admissions. These findings may assist shared decision-making about treatment of kidney failure.