Thomas W. Ferguson

Cystatin C as a biomarker for estimating glomerular filtration rate.

Purpose of reviewGlomerular filtration rate (GFR) is rarely measured in clinical practice because of the complexity of the measurement. As such, kidney function is typically estimated using validated study equations, which use readily available data including age, sex, race, and serum creatinine as filtration marker. Contemporary research suggests that cystatin C may be an improved alternative to creatinine for inclusion in GFR estimating equations. The purpose of this article is to evaluate the benefits and limitations of using cystatin C as a biomarker of filtration. Recent findingsCystatin C has fewer non-GFR determinants, when compared with serum creatinine. Use of serum cystatin C avoids the limitations related to both diet and muscle mass that affect serum creatinine. Cystatin C may be more accurate than serum creatinine in estimating GFR, and is more strongly associated with all-cause mortality and cardiovascular events. SummaryCystatin C has some advantages over serum creatinine in estimating GFR. The use of cystatin C as a confirmatory biomarker in deciding medication dosages or as a confirmatory test in patients with an uncertain diagnosis of chronic kidney disease may be beneficial.

The diagnostic accuracy of tests for latent tuberculosis infection in hemodialysis patients: a systematic review and meta-analysis.

Background Reactivation of latent Mycobacterium tuberculosis infection is an important health concern for patients on hemodialysis because of their immunosuppressed state and in kidney transplant patients receiving immunosuppressive therapy to prevent organ rejection. There are several tests available to determine the presence of latent tuberculosis infection: the tuberculin skin test (TST), QuantiFERON-TB Gold (QFT-G), and T-SPOT.TB. The objective of this study is to evaluate the diagnostic accuracy of these tests in determining latent tuberculosis infection in the hemodialysis population. Methods The study design was a systematic review. We selected studies with adequate information to ascertain test sensitivity or specificity of the TST, QFT-G, and TSPOT.TB with regards to determining latent tuberculosis infection in the hemodialysis population. Results One hundred two articles were selected for full review, and 17 were included in the meta-analysis. The TST had a pooled sensitivity of 31% (26%–36%, 95% confidence interval) and specificity of 63% (60%–65%) across eight studies. The QFT-G test had a pooled sensitivity of 53% (46%–59%) and specificity of 69% (65%–72%) across nine studies. The T-SPOT.TB test had a pooled sensitivity of 50% (42%–59%) and specificity of 67% (61%–73%) across three studies. Conclusion The QFT-G and the T-SPOT.TB tests were more sensitive than the TST for diagnosis of latent tuberculosis infection in patients on hemodialysis while offering a comparable level of specificity. This systematic review calls into question the practice of using the TST to screen in this population, especially in patients considered for kidney transplantation.

The Patterns, Risk Factors, and Prediction of Progression in Chronic Kidney Disease: A Narrative Review

Chronic kidney disease (CKD) is a global public health problem that is associated with excess morbidity, mortality, and health resource utilization. The progression of CKD is defined by a decrease in glomerular filtration rate and leads to a variety of metabolic abnormalities including acidosis, hypertension, anemia, and mineral bone disorder. Lower glomerular filtration rate also bears a strong relationship with an increased risk of cardiovascular events, end-stage renal disease, and death. Patterns of CKD progression include linear and nonlinear trajectories, but kidney function can remain stable for years in some individuals. Addressing modifiable risk factors for the progression of CKD is needed to attenuate its associated morbidity and mortality. Developing effective risk prediction models for CKD progression is critical to identify patients who are more likely to benefit from interventions and more intensive monitoring. Accurate risk-prediction algorithms permit systems to best align health care resources with risk to maximize their effects and efficiency while guiding overall decision making.

Cost-effective treatment modalities for reducing morbidity associated with chronic kidney disease

Chronic kidney disease (CKD) is a worldwide health problem with increasing prevalence and incidence. Guidelines suggest that early referral to a nephrologist to manage advanced stage (4+) patients with CKD is an effective treatment strategy, with earlier stage patients best managed through primary care physicians. Should patients with CKD progress to total kidney failure, several therapies are available that vary widely in costs. Kidney transplantation offers the lowest costs and highest quality of life, followed in ascending order of costs by peritoneal dialysis, home hemodialysis and facility-based hemodialysis. Earlier detection of CKD may prevent progression to kidney failure, and accurate risk prediction of end-stage kidney failure may improve clinical planning, outcomes and resource allocation.

Prevalence of frailty in Canadians 18–79 years old in the Canadian Health Measures Survey

BackgroundThere is little certainty as to the prevalence of frailty in Canadians in younger adulthood. This study examines and compares the prevalence of frailty in Canadians 18–79 years old using the Accumulation of Deficits and Fried models of frailty.MethodsThe Canadian Health Measures Study data were used to estimate the prevalence of frailty in adults 18–79 years old. A 23-item Frailty Index using the Accumulation of Deficits Model (cycles 1–3; n = 10,995) was developed; frailty was defined as having the presence of 25% or more indices, including symptoms, chronic conditions, and laboratory variables. Fried frailty (cycles 1–2; n = 7,353) included the presence of ≥3 criteria: exhaustion, physical inactivity, poor mobility, unintentional weight loss, and poor grip strength.ResultsThe prevalence of frailty was 8.6 and 6.6% with the Accumulation of Deficits and the Fried Model. Comparing the Fried vs. the Accumulation of Deficits Model, the prevalence of frailty was 5.3% vs. 1.8% in the 18–34 age group, 5.7% vs. 4.3% in the 35–49 age group, 6.9% vs. 11.6% in the 50–64 age group, and 7.8% vs. 20.2% in the 65+ age group. Some indices were higher in the younger age groups, including persistent cough, poor health compared to a year ago, and asthma for the accumulation of deficits model, and exhaustion, unintentional weight loss, and weak grip strength for the Fried model, compared to the older age groups.ConclusionsThese data show that frailty is prevalent in younger adults, but varies depending on which frailty tool is used. Further research is needed to determine the health impact of frailty in younger adults.

Screening for chronic kidney disease in Canadian indigenous peoples is cost-effective

Canadian indigenous (First Nations) have rates of kidney failure that are 2- to 4-fold higher than the non-indigenous general Canadian population. As such, a strategy of targeted screening and treatment for CKD may be cost-effective in this population. Our objective was to assess the cost utility of screening and subsequent treatment for CKD in rural Canadian indigenous adults by both estimated glomerular filtration rate and the urine albumin-to-creatinine ratio. A decision analytic Markov model was constructed comparing the screening and treatment strategy to usual care. Primary outcomes were presented as incremental cost-effectiveness ratios (ICERs) presented as a cost per quality-adjusted life-year (QALY). Screening for CKD was associated with an ICER of

The Cost Effectiveness of Erythropoietin-Stimulating Agents for Treating Anemia in Patients on Dialysis: A Systematic Review

23,700/QALY in comparison to usual care. Restricting the model to screening in communities accessed only by air travel (CKD prevalence 34.4%), this ratio fell to

Safety of Intravenous Iron in Dialysis A Systematic Review and Meta-Analysis

7,790/QALY. In road accessible communities (CKD prevalence 17.6%) the ICER was

Pro: Risk scores for chronic kidney disease progression are robust, powerful and ready for implementation

52,480/QALY. The model was robust to changes in influential variables when tested in univariate sensitivity analyses. Probabilistic sensitivity analysis found 72% of simulations to be cost-effective at a

An Economic Assessment Model of Rural and Remote Satellite Hemodialysis Units

50,000/QALY threshold and 93% of simulations to be cost-effective at a