Low-dose drug therapy is promoted as a way to maximize benefit and minimize adverse drug effects when prescribing for older adults. This population-based study evaluates the age and sex-related use of two common therapies: thiazide diuretics, where evidence supports the use of low-dose therapy, and beta-blockers, where trials have not evaluated the minimum effective dose.
Using linked administrative databases we identified all of the 120,613 persons dispensed a thiazide diuretic therapy and 12,908 myocardial infarction survivors dispensed beta-blocker therapy in Canada's largest province. We used logistic regression models to study the association of age and sex with dispensing of low-dose thiazide diuretic and beta-blocker therapy at doses lower than evaluated in trials.
Of 120,613 older people dispensed a thiazide diuretic, 32,372 (26.8%) were dispensed a low dose. Patients 85 years of age or older, relative to the youngest group, were 30% more likely to be dispensed low-dose therapy (OR=1.31; 95% CI, 1.27 to 1.36; P
We sought to determine whether more comprehensive risk-adjustment models have a significant impact on hospital risk-adjusted mortality rates after coronary artery bypass graft surgery (CABG) in Ontario, Canada.
The Working Group Panel on the Collaborative CABG Database Project has categorized 44 clinical variables into 7 core, 13 level 1 and 24 level 2 variables, to reflect their relative importance in determining short-term mortality after CABG.
Using clinical data for all 5,517 patients undergoing isolated CABG in Ontario in 1993, we developed 12 increasingly comprehensive risk-adjustment models using logistic regression analysis of 6 of the Panel's core variables and 6 of the Panel's level 1 variables. We studied how the risk-adjusted mortality rates of the nine cardiac surgery hospitals in Ontario changed as more variables were included in these models.
Incorporating six of the core variables in a risk-adjustment model led to a model with an area under the receiver operating characteristic (ROC) curve of 0.77. The ROC curve area slightly improved to 0.79 with the inclusion of six additional level 1 variables (p = 0.063). Hospital risk-adjusted mortality rates and relative rankings stabilized after adjusting for six core variables. Adding an additional six level 1 variables to a risk-adjustment model had minimal impact on overall results.
A small number of core variables appear to be sufficient for fairly comparing risk-adjusted mortality rates after CABG across hospitals in Ontario. For efficient interprovider comparisons, risk-adjustment models for CABG could be simplified so that only essential variables are included in these models.
Prior comparisons of administrative versus clinical data for creating coronary artery bypass graft (CABG) surgery outcome "report cards" are all from the United States and yield inconsistent conclusions regarding the validity of administrative data report cards. In this study, we compared 2 CABG surgery outcome report cards for Ontario, Canada: one derived from clinical data from the Cardiac Care Network of Ontario and one derived from administrative data from the Canadian Institute for Health Information.
Data from 4 fiscal years, 1992-93 through 1995-96, were used. The Canadian Institute for Health Information report card was derived from administrative data only. The Cardiac Care Network report card drew on prospectively collected clinical information that included variables such as left ventricular ejection fraction but also required linkages to the Canadian Institute for Health Information data for ascertainment of selected comorbidities and in-hospital mortality rates. Logistic regression models were used to calculate risk-adjusted death rates for each of the 9 hospitals performing CABG surgery in Ontario.
The risk-adjusted death rates were quite similar between data sources for 7 of the 9 hospitals. For 2 hospitals, rather large absolute differences in adjusted death rates of 0.58% and 0.64% were seen between report cards. There was a strong correlation between data sources for risk-adjusted hospital death rates (intraclass correlation coefficient = 0.927, P
The objective of this study was to compare the classification of hospitals as outcomes outliers using a commonly implemented frequentist statistical approach vs. an implementation of Bayesian hierarchical statistical models, using 30-day hospital-level mortality rates for a cohort of acute myocardial infarction patients as a test case. For the frequentist approach, a logistic regression model was constructed to predict mortality. For each hospital, a risk-adj usted mortality rate was computed. Those hospitals whose 95% confidence interval, around the risk-adjusted mortality rate, excludes the mean mortality rate were classified as outliers. With the Bayesian hierarchical models, three factors could vary: the profile of the typical patient (low, medium or high risk), the extent to which the mortality rate for the typical patient departed from average, and the probability that the mortality rate was indeed different by the specified amount. The agreement between the two methods was compared for different patient profiles, threshold differences from the average and probabilities. Only marginal agreement was shown between the Bayesian and frequentist approaches. In only five of the 27 comparisons was the kappa statistic at least 0.40. The remaining 22 comparisons demonstrated only marginal agreement between the two methods. Within the Bayesian framework, hospital classification clearly depended on patient profile, threshold and probability of exceeding the threshold. These inconsistencies raise questions about the validity of current methods for classifying hospital performance, and suggest a need for urgent research into which methods are most meaningful to clinicians, managers and the general public.
Previous studies have shown that the rate of coronary artery bypass graft (CABG) surgery is much higher in New York State than in Ontario.
To compare the service context and clinical characteristics of patients having CABG surgery in New York and Ontario.
Retrospective analysis of data from cardiac surgery registries in New York and Ontario.
All 16,690 patients in New York and 5517 patients in Ontario who had isolated CABG surgery in 1993.
Clinical characteristics of patients having CABG surgery and rates of CABG surgery by coronary anatomy.
The overall age-adjusted rate of isolated CABG surgery was 1.79 times (95% CI, 1.74 to 1.85) greater in New York than in Ontario. Patients who had CABG surgery in New York were more likely to be elderly and female and to have recently had myocardial infarction (P
Comment In: Ann Intern Med. 1997 Aug 1;127(3):244-59245239
This study was conducted to assess the overall mortality rate and the amount of interhospital variation in risk-adjusted mortality rates after coronary artery bypass graft (CABG) surgery in Ontario, Canada. CABG outcomes data are not publicly disseminated in Ontario.
Clinical risk factors and surgical outcomes were collected on 15,608 patients undergoing isolated CABG surgery between April 1, 1991, and March 31, 1994, at the nine hospitals performing adult cardiac surgery in Ontario. The data were analyzed on the basis of a fiscal year. The overall mortality rate was 3.01%, and the risk-adjusted mortality rate declined from 3.17% in 1991 to 2.93% in 1993. In 1991, one of the nine hospitals had a risk-adjusted mortality rate significantly lower than the provincial average. Otherwise, the hospitals all had risk-adjusted mortality rates within the expected range during the time period of the study. All hospitals performed > 300 CABG procedures in 1992 and 1993, and only 2 of 42 cardiac surgeons performed
increasingly, ICD implantation is performed without defibrillation testing (DT).
To determine the current frequency of DT, the risks associated with DT, and to understand how physicians select patients to have DT.
between January 2007 and July 2008, all patients in Ontario, Canada who received an ICD were enrolled in this prospective registry.
a total of 2,173 patients were included; 58% had new ICD implants for primary prevention, 25% for secondary prevention, and 17% had pulse generator replacement. DT was carried out at the time of ICD implantation or predischarge in 65%, 67%, and 24% of primary, secondary, and replacement cases respectively (P = 20% (OR = 1.3, P = 0.05). A history of atrial fibrillation (OR = 0.58, P = 0.0001) or oral anticoagulant use (OR = 0.75, P = 0.03) was associated with a lower likelihood of having DT. Age, gender, NYHA class, and history of stroke or TIA did not predict DT. Perioperative complications, including death, myocardial infarction, stroke, tamponade, pneumothorax, heart failure, infection, wound hematoma, and lead dislodgement, were similar among patients with (8.7%) and without (8.3%) DT (P = 0.7)
DT is performed in two-thirds of new ICD implants but only one-quarter of ICD replacements. Physicians favored performance of DT in patients who are at lower risk of DT-related complications and in those receiving amiodarone. DT was not associated with an increased risk of perioperative complications.
Although mass screening for osteoporosis is not recommended among postmenopausal women, there is no consensus on which women should undergo testing for low bone mineral density. The objective of this study was to develop and validate a clinical tool to help clinicians identify which women are at increased risk for osteoporosis and should therefore undergo further testing with bone densitometry.
Using Ontario baseline data from the Canadian Multicentre Osteoporosis Study, we identified all cognitively normal women aged 45 years or more who had undergone testing with dual-energy x-ray absorptiometry (DXA) at both the femoral neck and the lumbar spine (L1-L4). Participants who had a previous diagnosis of osteoporosis or were taking bone active medication other than ovarian hormones were excluded. The main outcome measure was low bone mineral density (T score of 2 or more standard deviations below the mean for young Canadian women) at either the femoral neck or the lumbar spine. Logistic regression analysis and receiver operating characteristic (ROC) analysis were used to identify the simplest algorithm that would identify women at increased risk for low bone mineral density.
The study population comprised 1376 women, of whom 926 were allocated to the development of the tool and 450 to its validation. A simple algorithm based on age, weight and current estrogen use (yes or no) was developed. Validation of this 3-item Osteoporosis Risk Assessment Instrument (ORAI) showed that the tool had a sensitivity of 93.3% (95% confidence interval [CI] 86.3%-97.0%) and a specificity of 46.4% (95% CI 41.0%-51.8%) for selecting women with low bone mineral density. The sensitivity of the instrument for selecting women with osteoporosis was 94.4% (95% CI 83.7%-98.6%). Use of the ORAI represented a 38.7% reduction in DXA testing compared with screening all women in our study.
The ORAI accurately identifies the vast majority of women likely to have low bone mineral density and is effective in substantially decreasing the need for all women to undergo DXA testing.
Cites: Radiology. 1982 Apr;143(1):29-367063747
Cites: N Engl J Med. 1985 Sep 26;313(13):793-93897864
Cites: Radiology. 1987 Aug;164(2):405-103602377
Cites: Biometrics. 1988 Sep;44(3):837-453203132
Cites: CMAJ. 1994 Jul 15;151(2):177-858039063
Cites: J Bone Miner Res. 1994 Oct;9(10):1503-147817795