Cardiac Catheterization In Alberta Research Articles

Psychometric evaluation of a Canadian version of the Seattle Angina Questionnaire (SAQ-CAN)

BackgroundThe Seattle Angina Questionnaire (SAQ) is a widely-used patient-reported outcomes measure in patients with heart disease. This study assesses the validity and reliability of the SAQ in a Canadian cohort of individuals with stable angina.Methods and resultsData are from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry, a population-based registry of patients who received cardiac catheterization in Alberta, Canada. The cohort consists of 4052 patients undergoing cardiac catheterization for stable angina and completed the SAQ within 2 weeks. Exploratory factor analysis and confirmatory factor analysis (CFA) were used to assess the factorial structure of the SAQ. Internal and test–retest reliabilities of a new measure (i.e., SAQ-CAN) was measured using Cronbach α and intraclass correlation coefficient, respectively. CFA model fit was assessed using the root mean square error of approximation (RMSEA) and comparative fit index (CFI). Construct validity of the SAQ-CAN was assessed in relation to Hospital Anxiety and Depression Scales (HADS), Euro Quality of life 5 dimension (EQ5D), and original SAQ. Of the 4052 patients included in this analysis, 3281 (80.97%) were younger than 75 years old, while 3239 (79.94%) were male. Both exploratory and confirmatory factor analyses revealed a four-factorial structure consisting of 16 items that provided a better fit to the data (RMSEA = 0.049 [90% CI = (0.047, 0.052)]; CFI = 0.975). The 16-item SAQ demonstrated good to excellent internal reliability (Cronbach’s α range from 0.77 to 0.90), moderate to strong correlation with the Original SAQ and EQ5D but negligible correlations with HADS.ConclusionThe SAQ-CAN has acceptable psychometric properties that are comparable to the original SAQ. We recommend its use for assessing coronary health outcomes in Canadian patients with Coronary Artery Disease.

Ensemble-based Classification Models for Predicting Post-Operative Mortality Risk in Coronary Artery Disease

IntroductionThere has been an increased demand for more accurate prediction tools to aid clinical decision-making regarding disease diagnosis prognosis for coronary artery disease(CAD) patients. Patients undergoing CABG surgery are older and a larger number have had previous heart surgery. Consequently, mortality after CABG is expected to increase despite procedural advances.
 Objectives and ApproachThis study aims to compare the predictive performance of random forest(RF) and logistic regression(LR) classifiers for predicting 30-day and 1-year post-operative mortality risk in CAD patients who underwent CABG. Data was obtained by linking the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease(APPROACH) registry, a prospective longitudinal data of patients undergoing cardiac catheterization in Alberta, Canada, to vital statistics database. All patients who underwent first-time isolated CABG between January 1, 2007 and December 31, 2012 were included in the analysis. Area under the receiver operating curve(AUC) was used to compare the predictive performance of LR and RF regression.
 ResultsOf the 4,908 eligible subjects who underwent isolated CABG during the study period, mortality estimates of 30-day and 1-year post CABG surgery were 1.59% and 3.85%, respectively. Descriptive analysis revealed that age, sex, hypertension, dialysis, cerebrovascular disease, chronic obstructive pulmonary disease, and chronic heart failure were associated with 30-day and 1-year mortality. The accuracy of the LR and RF regression classifiers in predicting 30-day mortality were 74.1, and 99.7%, respectively. While the accuracy of the former and latter classifiers in predicting 1-year post CABG mortality were 74% and 97.4%, respectively.
 Conclusion/ImplicationsThis study shows that RF classifier results in better predictive accuracy than LR in predicting post-operating mortality risk in CAD patients. Machine learning models are potentially usefully for developing clinical prediction models that can be used to aid the monitoring of post-discharge outcomes in the management of cardiovascular diseases.

Recent Temporal Trends and Geographic Distribution of Cardiac Procedures in Alberta

BackgroundPrior Canadian studies of cardiac procedure rates showed changes over time and regional variability, but more recent Canadian cardiac procedure rates are unknown. MethodsWe performed a study using the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease registry to evaluate the temporal trends and geographic distribution of cardiac procedures in Alberta from April 1, 2003 through March 31, 2010. Rates were age- and sex-standardized by means of the 1996 Canadian census. ResultsWhile the raw number of cardiac catheterizations in Alberta was nearly uniform through the study period, age- and sex-standardized cardiac catheterizations declined from a rate of 480 per 100,000 in 2003 to a rate of 430 per 100,000 in 2010. The percutaneous coronary intervention (PCI) rates also declined, from a rate of 186 per 100,000 in 2003 to 170 per 100,000 in 2010. The rates for coronary artery bypass grafts declined from 84 per 100,000 in 2003 to 42 per 100,000 in 2010. There was geographic variability, with northern regions characterized by rates that were higher than the provincial average rates, and southern regions characterized by rates lower than the provincial average. ConclusionDuring the study period, age- and sex-standardized rates of cardiac catheterization and PCI in Alberta declined, reversing previous trends of increasing PCI rates. The rates of coronary artery bypass grafts in Alberta declined significantly, suggesting a change in practice consistent with that seen elsewhere. There are geographic differences in rates of cardiac procedures. These data have implications for other regions of Canada, for which registry data may not be available.

Altered health status and quality of life in South Asians with coronary artery disease

People of South Asian (SA) ancestry are susceptible to coronary artery disease (CAD). Although studies suggest that SA with CAD has a worse prognosis compared with Europeans, it is unknown whether corresponding differences in functional status and quality-of-life (QOL) measures exist. Accordingly, we compared symptoms, function, and QOL in SA and European Canadians with CAD using the Seattle Angina Questionnaire (SAQ). Using the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease, an outcomes registry that captures patients undergoing cardiac catheterization in Alberta, Canada, we identified 635 SA and 18,934 European patients with angiographic CAD from January 1995 to December 2006 who reported health status outcomes using the SAQ at 1 year after the index catheterization. To obtain comparable clinical variables among SA and Europeans, we used a propensity score-matching technique. One-year adjusted mean (SD) scores were significantly lower in SA compared with European Canadians for most SAQ domains: exertional capacity (75 [23] vs 80 [23], P = .011), anginal stability (77 [28] vs 77 [27], P = .627), anginal frequency (86 [23] vs 88 [20], P < .001), treatment satisfaction (86 [19] vs 89 [16], P < .001), and SAQ QOL (71 [24] vs 76 [21], P < .001). These results could not be accounted for by differences in baseline QOL scores or changes in health status from baseline to 1 year. South Asian Canadians with established CAD have significantly worse health status outcomes at 1 year after angiography compared with European Canadians. Further studies are warranted to improve functional outcomes in SA with CAD.

Quality of life after coronary revascularization in the elderly

To describe health status outcomes at 4 years for a cohort of elderly patients with cardiac disease. Using the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease, an outcomes initiative capturing all patients undergoing cardiac catheterization in Alberta, Canada, health status was measured using the Seattle Angina Questionnaire (SAQ) and crude and risk-adjusted outcomes were determined and compared for patients treated with percutaneous coronary intervention or coronary artery bypass surgery (CABG) vs. medical therapy. Response rates among surviving, consenting patients were 64.8% for patients <70 years (n=7883), 77.3% for patients aged 70-79 years (n=2940), and 77.7% for patients >or=80 years of age (n=439). For patients aged <70 years, and those aged 70-79 years, for all dimensions of the SAQ, scores were significantly better for patients treated with revascularization procedures than with medical therapy. For patients over the age of 80 years, scores for patients treated with CABG in particular were significantly better, with the exception of exertional capacity. At 3 years, all scores remained stable or improved, and continued to favour revascularization. Elderly patients undergoing revascularization have better health status at 4 years than do those in the same age group who do not undergo revascularization. These findings suggest that age should not deter against revascularization given the combined survival and quality-of-life benefits.

Population rates of cardiac catheterization and yield of high-risk coronary artery disease

The optimal population rate of cardiac catheterization is unknown. One potential way to determine it would be to examine whether there is a population rate beyond which the yield of high-risk coronary artery disease (CAD) does not rise. Using a detailed clinical registry that captures all patients undergoing cardiac catheterization in Alberta, we determined annual population rates of cardiac catheterization and the corresponding yield of cases of high-risk CAD in each of Alberta's 17 health regions from 1995 to 2002. Least squares linear regression analysis and hierarchical modelling methods were then used to assess the linear relation between catheterization rates and rates of high-risk CAD. The age-adjusted average rate of cardiac catheterization among men ranged from 404.9 to 638.1 per 100,000 population aged over 20 years. Among women, the average rate ranged from 171.8 to 314.0 per 100,000. For both sexes, increased regional rates of catheterization were associated with a linearly increasing yield of high-risk CAD, with no evidence of a plateau in yield when more procedures were performed. One additional case of high-risk CAD was identified for every 2.5 additional cardiac catheterization procedures performed among men, and for every 3.7 additional procedures performed among women. The increasing yield of patients with high-risk CAD associated with increased regional population rates of cardiac catheterization, together with the absence of a plateau in yield, suggests that Alberta's population rates of cardiac catheterization are suboptimal to detect people with high-risk CAD.

Absence of bias against smokers in access to coronary revascularization after cardiac catheterization

Many consider smoking to be a personal choice for which individuals should be held accountable. We assessed whether there is any evidence of bias against smokers in cardiac care decision-making by determining whether smokers were as likely as non-smokers to undergo revascularization procedures after cardiac catheterization. Prospective cohort study. Subjects and setting. All patients undergoing cardiac catheterization in Alberta, Canada. Patients were categorized as current smokers, former smokers, or never smokers, and then compared for their risk-adjusted likelihood of undergoing revascularization procedures (percutaneous coronary intervention or coronary artery bypass grafting) after cardiac catheterization. Among 20406 patients undergoing catheterization, 25.4% were current smokers at the time of catheterization, 36.6% were former smokers, and 38.0% had never smoked. When compared with never smokers (reference group), the hazard ratio for undergoing any revascularization procedure after catheterization was 0.98 (95% CI 0.93-1.03) for current smokers and 0.98 (0.94-1.03) for former smokers. The hazard ratio for undergoing coronary artery bypass grafting was 1.09 (1.00-1.19) for current smokers and 1.00 (0.93-1.08) for former smokers. For percutaneous coronary intervention, the hazard ratios were 0.93 (0.87-0.99) for current smokers and 1.00 (0.94-1.06) for former smokers. Despite potential for discrimination on the basis of smoking status, current and former smokers undergoing cardiac catheterization in Alberta, Canada were as likely to undergo revascularization procedures as catheterization patients who had never smoked.

Survival after coronary revascularization among patients with kidney disease.

The optimal approach to revascularization in patients with kidney disease has not been determined. We studied survival by treatment group (CABG, percutaneous coronary intervention [PCI], or no revascularization) for patients with 3 categories of kidney function: dialysis-dependent kidney disease, non-dialysis-dependent kidney disease, and a reference group (serum creatinine <2.3 mg/dL). Data were derived from the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH), which captures information on all patients undergoing cardiac catheterization in Alberta, Canada. Characteristics and patient survival in 662 dialysis patients (1.6%) and 750 non-dialysis-dependent kidney disease patients (1.8%) were compared with the remainder of the 40,374 patients (96.6%). For the reference group, the adjusted 8-year survival rates for CABG, PCI, and no revascularization (NR) were 85.5%, 80.4%, and 72.3%, respectively (P<0.001 for CABG versus NR; P<0.001 for PCI versus NR). Adjusted survival rates were 45.9% for CABG, 32.7% for PCI, and 29.7% for NR in the nondialysis kidney disease group (P<0.001 for CABG versus NR; P=0.48 for PCI versus NR) and 44.8% for CABG, 41.2% for PCI, and 30.4% for NR in the dialysis group (P=0.003 for CABG versus NR; P=0.03 for PCI versus NR). Compared with no revascularization, CABG was associated with better survival in all categories of kidney function. PCI was also associated with a lower risk of death than no revascularization in reference patients and dialysis-dependent kidney disease patients but not in patients with non-dialysis-dependent kidney disease. The presence of kidney disease or dependence on dialysis should not be a deterrent to revascularization, particularly with CABG.

Sex differences in outcomes after cardiac catheterization: effect modification by treatment strategy and time.

Studies comparing outcomes of cardiac care in women vs men yield various results, with some suggesting worse outcomes for women and others suggesting equivalent outcomes. To determine whether extent of coronary disease, treatment strategy, and follow-up time influence the risk of death in women vs men among patients who have had cardiac catheterization. We studied a large inception cohort by using detailed clinical data from a registry of 37 401 patients undergoing cardiac catheterization in Alberta, Canada, from 1995-2000, with follow-up through December 31, 2001. The risk of death for women vs men was assessed for all patients combined and then in analyses stratified by degree of coronary anatomic risk and by treatment strategy (no revascularization, percutaneous coronary intervention [PCI], coronary artery bypass graft [CABG] surgery). The latter analysis included a graphic assessment of the changing relative risk over time for women vs men. Women had higher 1-year mortality than men did (5.6% vs 4.6%; P<.001). However, stratified analyses demonstrated that sex differences in risk occurred only early after catheterization and were most apparent among patients undergoing revascularization. The early risk-adjusted relative risks for women vs men were elevated at 3.49 (95% confidence interval [CI], 1.95-6.24) for CABG surgery and 2.38 (95% CI, 1.48-3.83) for PCI on day 1 after catheterization, with a subsequent decrease in relative risk over time to equivalence in risk between sexes before 1 year. Sex-based differences in death rates after cardiac catheterization are time- and treatment-specific. This finding may at least partially explain the discrepancies in results from earlier studies on sex differences in outcomes of cardiac care.

Misclassification of Income Quintiles Derived from Area-based Measures

Census-based methods are often used to estimate socioeconomic status. We assessed the agreement between Forward Sortation Area (FSA) and Enumeration Area (EA) derived income levels for all patients undergoing cardiac catheterization in Alberta, Canada, from 1995-1998.Income quintiles were calculated from census data for FSA and EA level. FSA- and EA-derived income measures were compared for misclassification. Both methods were then applied to the data to determine 4-year survival by income grouping in 21,446 patients following catheterization.The variability in EA-derived incomes for any given FSA-derived income is large. Only 40% of income quintiles are in agreement between the methods. For EA-based analyses, there is a linear relationship between higher income and lower mortality across all quintiles, while for FSA-based analyses, only the lowest income quintile had significantly higher mortality.Assuming that FSA-based methods are more likely to misclassify income compared to EA-based measures, the results for the FSA-based analyses are more likely to be erroneous. EA-derived measures should therefore be used when individual data are not available.

Misclassification of income quintiles derived from area-based measures. A comparison of enumeration area and forward sortation area.

Census-based methods are often used to estimate socioeconomic status. We assessed the agreement between Forward Sortation Area (FSA) and Enumeration Area (EA) derived income levels for all patients undergoing cardiac catheterization in Alberta, Canada, from 1995-1998. Income quintiles were calculated from census data for FSA and EA level. FSA- and EA-derived income measures were compared for misclassification. Both methods were then applied to the data to determine 4-year survival by income grouping in 21,446 patients following catheterization. The variability in EA-derived incomes for any given FSA-derived income is large. Only 40% of income quintiles are in agreement between the methods. For EA-based analyses, there is a linear relationship between higher income and lower mortality across all quintiles, while for FSA-based analyses, only the lowest income quintile had significantly higher mortality. Assuming that FSA-based methods are more likely to misclassify income compared to EA-based measures, the results for the FSA-based analyses are more likely to be erroneous. EA-derived measures should therefore be used when individual data are not available.

Prognostic significance of diabetes as a predictor of survival after cardiac catheterization

PURPOSE: Diabetes is a recognized risk factor for the development of cardiac disease, but its importance as a prognostic factor among patients with known cardiovascular disease is less clear. We evaluated survival in patients with and without diabetes who underwent cardiac catheterization for presumed coronary artery disease. SUBJECTS AND METHODS: We analyzed data from a prospective cohort study that captures detailed clinical information and longitudinal outcomes for all patients who undergo cardiac catheterization in Alberta, Canada. We studied 11,468 patients, 1959 (17%) of whom had diabetes. Logistic regression was used to model predictors of 1-year mortality, and proportional hazards analysis was used to model predictors of survival up to 3 years after cardiac catheterization. RESULTS: One-year mortality was 7.6% for patients with diabetes versus 4.1% for those without diabetes (odds ratio = 1.9, 95% confidence interval [CI]: 1.6 to 2.3). After adjusting for other characteristics of the patients, including comorbid conditions, previous cardiac history, coronary anatomy, and renal function, the odds ratio for 1-year mortality was 1.1 (95% CI: 0.8 to 1.3). Similarly, the adjusted hazard ratio for longer term mortality was 1.2 (95% CI: 1.0 to 1.4, mean follow-up of 702 days). CONCLUSIONS: These results suggest that there is little or no independent association between diabetes and mortality for up to 3 years after cardiac catheterization. Estimates of short- to intermediate-term prognosis for diabetic patients with coronary artery disease should be based on the presence of other prognostic factors associated with diabetes.