Fiona Clement

Overview of the Alberta Kidney Disease Network

BackgroundThe Alberta Kidney Disease Network is a collaborative nephrology research organization based on a central repository of laboratory and administrative data from the Canadian province of Alberta.DescriptionThe laboratory data within the Alberta Kidney Disease Network can be used to define patient populations, such as individuals with chronic kidney disease (using serum creatinine measurements to estimate kidney function) or anemia (using hemoglobin measurements). The administrative data within the Alberta Kidney Disease Network can also be used to define cohorts with common medical conditions such as hypertension and diabetes. Linkage of data sources permits assessment of socio-demographic information, clinical variables including comorbidity, as well as ascertainment of relevant outcomes such as health service encounters and events, the occurrence of new specified clinical outcomes and mortality.ConclusionThe unique ability to combine laboratory and administrative data for a large geographically defined population provides a rich data source not only for research purposes but for policy development and to guide the delivery of health care. This research model based on computerized laboratory data could serve as a prototype for the study of other chronic conditions.

Efficacy of statins for primary prevention in people at low cardiovascular risk: a meta-analysis

Background: Statins were initially used to improve cardiovascular outcomes in people with established coronary artery disease, but recently their use has become more common in people at low cardiovascular risk. We did a systematic review of randomized trials to assess the efficacy and harms of statins in these individuals. Methods: We searched MEDLINE and EMBASE (to Jan. 28, 2011), registries of health technology assessments and clinical trials, and reference lists of relevant reviews. We included trials that randomly assigned participants at low cardiovascular risk to receive a statin versus a placebo or no statin. We defined low risk as an observed 10-year risk of less than 20% for cardiovascular-related death or nonfatal myocardial infarction, but we explored other definitions in sensitivity analyses. Results: We identified 29 eligible trials involving a total of 80 711 participants. All-cause mortality was significantly lower among patients receiving a statin than among controls (relative risk [RR] 0.90, 95% confidence interval [CI] 0.84–0.97) for trials with a 10-year risk of cardiovascular disease < 20% [primary analysis] and 0.83, 95% CI 0.73–0.94, for trials with 10-year risk < 10% [sensitivity analysis]). Patients in the statin group were also significantly less likely than controls to have nonfatal myocardial infarction (RR 0.64, 95% CI 0.49–0.84) and nonfatal stroke (RR 0.81, 95% CI 0.68–0.96). Neither metaregression nor stratified analyses suggested statistically significant differences in efficacy between high-and low-potency statins, or larger reductions in cholesterol. Interpretation: Statins were found to be efficacious in preventing death and cardiovascular morbidity in people at low cardiovascular risk. Reductions in relative risk were similar to those seen in patients with a history of coronary artery disease.

Intensive and Standard Blood Pressure Targets in Patients With Type 2 Diabetes Mellitus: Systematic Review and Meta-analysis

BACKGROUND Treatment of hypertension in patients with diabetes mellitus (DM) has been shown to improve cardiovascular outcomes; however, the value of intensive blood pressure (BP) targets remains uncertain. We sought to determine the effectiveness and safety of treating BP to intensive targets (upper limit of 130 mm Hg systolic and 80 mm Hg diastolic) compared with standard targets (upper limit of 140-160 mm Hg systolic and 85-100 mm Hg diastolic) in patients with type 2 DM. METHODS Using electronic databases, bibliographies, and clinical trial registries, we conducted a systematic review and meta-analysis to identify randomized trials enrolling adults diagnosed as having type 2 DM and comparing prespecified BP targets. Data on study characteristics, risk for bias, and outcomes were collected. Random-effects models were used to pool relative risks and risk differences for mortality, myocardial infarction, and stroke. RESULTS The use of intensive BP targets was not associated with a significant decrease in the risk for mortality (relative risk difference, 0.76; 95% CI, 0.55-1.05) or myocardial infarction (relative risk difference, 0.93; 95% CI, 0.80-1.08) but was associated with a decrease in the risk for stroke (relative risk, 0.65; 95% CI, 0.48-0.86). The pooled analysis of risk differences associated with the use of intensive BP targets demonstrated a small absolute decrease in the risk for stroke (absolute risk difference, -0.01; 95% CI, -0.02 to -0.00) but no statistically significant difference in the risk for mortality or myocardial infarction. CONCLUSION Although the use of intensive compared with standard BP targets in patients with type 2 DM is associated with a small reduction in the risk for stroke, evidence does not show that intensive targets reduce the risk for mortality or myocardial infarction.

The Impact of Selecting a High Hemoglobin Target Level on Health-Related Quality of Life for Patients With Chronic Kidney Disease A Systematic Review and Meta-analysis

BACKGROUND Treatment of anemia in chronic kidney disease (CKD) with erythropoietin-stimulating agents (ESAs) is commonplace. The optimal hemoglobin treatment target has not been established. A clearer understanding of the health-related quality of life (HQOL) impact of hemoglobin target levels is needed. We systematically reviewed the randomized controlled trial (RCT) data on HQOL for patients treated with low to intermediate (9.0-12.0 g/dL) and high hemoglobin target levels (>12.0 g/dL) and performed a meta-analysis of all available 36-item short-form (SF-36) RCT data. METHODS We conducted a search to identify all RCTs of ESA therapy in patients with anemia associated with CKD (1966-December 2006). Inclusion criteria were (1) 30 or more participants, (2) anemic adults with CKD, (3) epoetin (alfa and beta) or darbepoetin used, (4) a control arm, and (5) reported HQOL using a validated measure. All available SF-36 data underwent meta-analysis using the weighted mean difference. RESULTS Of 231 full texts screened, 11 eligible studies were identified. The SF-36 was used in 9 trials. Reporting of these data was generally incomplete. Data from each domain of the SF-36 were summarized. Statistically significant changes were noted in the physical function (weighted mean difference [WMD], 2.9; 95% confidence interval [CI], 1.3 to 4.5), general health (WMD, 2.7; 95% CI, 1.3 to 4.2), social function (WMD, 1.3; 95% CI, -0.8 to 3.4), and mental health (WMD, 0.4; 95% CI, 0.1 to 0.8) domains. None of the changes would be considered clinically significant. CONCLUSIONS Our study suggests that targeting hemoglobin levels in excess of 12.0 g/dL leads to small and not clinically meaningful improvements in HQOL. This, in addition to significant safety concerns, suggests that targeting treatment to hemoglobin levels that are in the range of 9.0 to 12.0 g/dL is preferred.

Nocturnal Hypoxia and Loss of Kidney Function

Background Although obstructive sleep apnea (OSA) is more common in patients with kidney disease, whether nocturnal hypoxia affects kidney function is unknown. Methods We studied all adult subjects referred for diagnostic testing of sleep apnea between July 2005 and December 31 2007 who had serial measurement of their kidney function. Nocturnal hypoxia was defined as oxygen saturation (SaO2) below 90% for ≥12% of the nocturnal monitoring time. The primary outcome, accelerated loss of kidney function, was defined as a decline in estimated glomerular filtration rate (eGFR) ≥4 ml/min/1.73 m2 per year. Results 858 participants were included and followed for a mean study period of 2.1 years. Overall 374 (44%) had nocturnal hypoxia, and 49 (5.7%) had accelerated loss of kidney function. Compared to controls without hypoxia, patients with nocturnal hypoxia had a significant increase in the adjusted risk of accelerated kidney function loss (odds ratio (OR) 2.89, 95% confidence interval [CI] 1.25, 6.67). Conclusion Nocturnal hypoxia was independently associated with an increased risk of accelerated kidney function loss. Further studies are required to determine whether treatment and correction of nocturnal hypoxia reduces loss of kidney function.

Enrolment in primary care networks: impact on outcomes and processes of care for patients with diabetes

Background: Primary care networks are a newer model of primary care that focuses on improved access to care and the use of multidisciplinary teams for patients with chronic disease. We sought to determine the association between enrolment in primary care networks and the care and outcomes of patients with diabetes. Methods: We used administrative health care data to study the care and outcomes of patients with incident and prevalent diabetes separately. For patients with prevalent diabetes, we compared those whose care was managed by physicians who were or were not in a primary care network using propensity score matching. For patients with incident diabetes, we studied a cohort before and after primary care networks were established. Each cohort was further divided based on whether or not patients were cared for by physicians enrolled in a network. Our primary outcome was admissions to hospital or visits to emergency departments for ambulatory care sensitive conditions specific to diabetes. Results: Compared with patients whose prevalent diabetes is managed outside of primary care networks, patients in primary care networks had a lower rate of diabetes-specific ambulatory care sensitive conditions (adjusted incidence rate ratio 0.81, 95% confidence interval [CI] 0.75 to 0.87), were more likely to see an ophthalmologist or optometrist (risk ratio 1.19, 95% CI 1.17 to 1.21) and had better glycemic control (adjusted mean difference −0.067, 95% CI −0.081 to −0.052). Interpretation: Patients whose diabetes was managed in primary care networks received better care and had better clinical outcomes than patients whose condition was not managed in a network, although the differences were very small.

The impact of using different costing methods on the results of an economic evaluation of cardiac care: microcosting vs gross-costing approaches.

BACKGROUND Published guidelines on the conduct of economic evaluations provide little guidance regarding the use and potential bias of the different costing methods. OBJECTIVES Using microcosting and two gross-costing methods, we (1) compared the cost estimates within and across subjects, and (2) determined the impact on the results of an economic evaluation. METHODS Microcosting estimates were obtained from the local health region and gross-costing estimates were obtained from two government bodies (one provincial and one national). Total inpatient costs were described for each method. Using an economic evaluation of sirolimus-eluting stents, we compared the incremental cost-utility ratios that resulted from applying each method. RESULTS Microcosting, Case-Mix-Grouper (CMG) gross-costing, and Refined-Diagnosis-Related grouper (rDRG) gross-costing resulted in 4-year mean cost estimates of

Reducing Frequent Visits to the Emergency Department: A Systematic Review of Interventions

16,684,

Systematic review of stroke thrombolysis service configuration

16,232, and

Health Care Costs in People With Diabetes and Their Association With Glycemic Control and Kidney Function

10,474, respectively. Using Monte Carlo simulation, the cost per QALY gained was