Biomedical subjects

Peter D Faris

Publications and source records attributed to Peter D Faris.

14 recordsLinked to original sources

PubMed2006

Kaplan-Meier methods yielded misleading results in competing risk scenarios.

BACKGROUND AND OBJECTIVE: Time-to-event curves are routinely presented in the medical literature. The most widely used method is the Kaplan-Meier (K-M) method, but this analysis approach may not be appropriate when an analysis focuses on time-to-first event in scenarios where there are competing events. We compared K-M methods applying various censoring approaches with the lesser-known "cumulative incidence competing risks" (CICR) method in an analysis of competing events. METHODS: A registry containing data on 21,624 patients undergoing cardiac catheterization was analyzed. Time to coronary artery bypass grafting (CABG) was assessed in an analysis for which percutaneous coronary intervention and death were competing events. Time-to-CABG curves were calculated using the "K-M censor all method," "K-M censor death only method," "K-M ignore all method," and the CICR method. RESULTS: One-year CABG rates calculated for the K-M "censor all," "censor death only," and "ignore all" methods were 28.8%, 22.8%, and 22.4%, respectively compared to the "actual" rate of 20.8%. For the CICR method, the corresponding 1-year rate was identical to the "actual" rate. CONCLUSION: In situations with competing risks, and where an analysis focuses on first events, the CICR method is most appropriate, as K-M methods will tend to overestimate event rates.

Angioplasty, Balloon, Coronary↗

PubMed2005

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. INTERPRETATION: 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.

Adult↗

PubMed2005

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

OBJECTIVE: 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. DESIGN: Prospective cohort study. Subjects and setting. All patients undergoing cardiac catheterization in Alberta, Canada. MAIN MEASURE: 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. RESULTS: 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. CONCLUSION: 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.

Alberta↗

PubMed2004

Accuracy of city postal code coordinates as a proxy for location of residence.

BACKGROUND: Health studies sometimes rely on postal code location as a proxy for the location of residence. This study compares the postal code location to that of the street address using a database from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACHCopyright ). Cardiac catheterization cases in an urban Canadian City were used for calendar year 1999. We determined location in meters for both the address (using the City of Calgary Street Network File in ArcView 3.2) and postal code location (using Statistic Canada's Postal Code Conversion File). RESULTS: The distance between the two estimates of location for each case were measured and it was found that 87.9% of the postal code locations were within 200 meters of the true address location (straight line distances) and 96.5% were within 500 meters of the address location (straight line distances). CONCLUSIONS: We conclude that postal code locations are a reasonably accurate proxy for address location. However, there may be research questions for which a more accurate description of location is required.

Journal Article↗

PubMed2004

Diagnostic cardiac catheterization and revascularization rates for coronary heart disease.

BACKGROUND: Despite evidence of regional variation across North America, there have been no comprehensive studies of cardiac procedure rates for coronary heart disease in Canada. OBJECTIVES: To use available administrative data and a survey of catheterization facilities to examine regional and demographic variations in cardiovascular procedure rates. METHODS: A survey of all cardiac catheterization facilities in Canada was conducted, and the procedure counts from these facilities were used to determine provincial catheterization rates from 1997/1998 to 2001/2002. Procedure counts for 1997/1998 to 1999/2000 for coronary artery bypass graft (CABG) surgery and percutaneous coronary intervention (PCI) were provided by the Canadian Institute for Health Information and used to calculate revascularization procedure rates. Population projections provided by Statistics Canada were used as denominators for calculating the rates, and direct standardization was used to obtain age- and sex-adjusted rates. RESULTS AND CONCLUSIONS: The crude rate of cardiac catheterization in Canada increased from 359.9 to 471.5 per 100,000 population across the five years studied. There was considerable variation in revascularization procedure rates across health regions and provinces. Between 1997/1998 and 1999/2000, there was little increase in the rate of CABGs performed in Canada but a marked increase in the rate of PCIs. For both CABG and PCI, rates were higher for men than women, and highest in the 65- to 74-year-old age category. This study provides a valuable 'snapshot' of cardiac procedure use rates but indicates a clear need for more comprehensive collection of cardiac care data in Canada.

Adult↗

PubMed2004

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

CONTEXT: 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. OBJECTIVE: 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. DESIGN, SETTING, AND PATIENTS: 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. MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSIONS: 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.

Aged↗

PubMed2004

Geographical location of residence and uniformity of access to cardiac revascularization services after catheterization.

BACKGROUND: The centralization of health care services has numerous potential benefits but April compromise access for individuals living in remote areas. OBJECTIVES: To examine the association between a patient's place of residence and the likelihood of undergoing a coronary revascularization procedure within one year after cardiac catheterization. METHODS: All Alberta residents undergoing cardiac catheterization between 1995 and 1998 were examined. Geographical distance from patient place of residence to a centralized catheterization facility was calculated. The adjusted odds of undergoing cardiac revascularization within one year of catheterization was determined as a function of distance, controlling for differences in patient age, clinical factors and economic status. RESULTS: Of 21816 residents who underwent cardiac catheterization in the province, 10997 had a revascularization procedure. Graphical examination of distance revealed a change in revascularization rates in patients living more than 450 km from revascularization centres. Further analysis was conducted using this cutpoint. Patients living in these remote areas were more likely to undergo a coronary revascularization procedure within the next year (adjusted odds ratio 1.65, 95% CI 1.05 to 2.59). However, these same residents were also less likely to undergo catheterization in the first place when compared with other Albertans (270 versus 398 procedures per 100000 population). CONCLUSION: Only a small proportion of the population living in Alberta's most remote areas were more likely to undergo a revascularization procedure, indicating a remarkable uniformity of access to revascularization after coronary cardiac catheterization has occurred. This study examines the use of an existing database to gain further insights into the relationship between geography and access to cardiac care, and the distance-access relationship for coronary revascularization in Alberta.

Alberta↗

PubMed2003

Bias in estimates of confidence intervals for health outcome report cards.

Health researchers commonly use logistic regression when profiling health providers. Data from the patients treated by the providers are used to construct models predicting the expected number of outcomes for providers and the ratio of observed to expected outcomes (O/E ratio) used as a risk-adjusted measure of provider performance. Typically, when calculating the standard deviation (SD) of O/E ratios, only O is treated as a random variable. We used the propagation of errors (Pe) to derive a SD estimate that accounted for variability in O and the estimate of E. Using data previously used to profile Canadian cardiac surgery providers, we compared Pe-SD estimates with typical SD (SDT) estimates. The SDT estimates and confidence intervals were always larger than the Pe estimates, most notably when one or more providers treated a large proportion of the patients. This was confirmed using computer simulations. SDT estimates should be abandoned in favor of more sophisticated estimates.

Bias↗

PubMed2003

Sex differences in the prognostic importance of diabetes in patients with ischemic heart disease undergoing coronary angiography.

OBJECTIVE: Women with ischemic heart disease have poorer outcomes than men and are suggested to have greater risk associated with diabetes. We evaluated the prognosis associated with diabetes, in analyses stratified by sex, to determine whether similar differences are seen in a large unselected cohort of patients. RESEARCH DESIGN AND METHODS: Using the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH), a clinical data collection and follow-up initiative capturing all patients undergoing cardiac catheterization in Alberta, Canada, the relative significance of diabetes on long-term survival in 13152 men and 4249 women was evaluated in patients presenting with or without myocardial infarction and according to first treatment received. RESULTS: The 1-year mortality rates were 4.7% and 6.8% in men and women (P < 0.001), 4.1% and 7.4% in nondiabetic and diabetic men (P < 0.001), and 5.8% and 9.6% in nondiabetic and diabetic women, respectively (P < 0.001). The risk-adjusted Cox proportional hazard ratios associated with diabetes in myocardial infarction were 1.03 in men and 1.20 in women. The diabetes hazard ratios for percutaneous coronary intervention were 1.28 in men and 1.40 in women, 1.23 in men and 1.32 in women for bypass surgery, and 1.26 in men and 1.31 in women for medical therapy (P = NS for all diabetes hazard ratio comparisons between men and women). CONCLUSIONS: Hazard ratios quantifying the adverse prognosis associated with diabetes in patients undergoing angiography are consistently higher among women than men, but the differences across sexes are not statistically significant. These slight sex differences noted in the APPROACH registry are similar to previously reported findings and may be clinically important.

Aged↗

PubMed2002

Survival after coronary revascularization in the elderly.

BACKGROUND: Elderly patients with ischemic heart disease are increasingly referred for coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI). However, reports of poor outcomes in the elderly have led to questions about the benefit of these strategies. We studied survival by prescribed treatment (CABG, PCI, or medical therapy) for patients in 3 age categories: <70 years, 70 to 79 years, and > or =80 years of age. METHODS AND RESULTS: The Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) is a clinical data collection and outcome monitoring initiative capturing all patients undergoing cardiac catheterization and revascularization in the province of Alberta, Canada, since 1995. Characteristics and long-term outcomes of a cohort of >6000 elderly patients with ischemic heart disease were compared with younger patients. In 15 392 patients >70 years of age, 4-year adjusted actuarial survival rates for CABG, PCI, and medical therapy were 95.0%, 93.8%, and 90.5%, respectively. In 5198 patients 70 to 79 years of age, survival rates were 87.3%, 83.9%, and 79.1%, respectively. In 983 patients > or = 80 years of age, survival was 77.4% for CABG, 71.6% for PCI, and 60.3% for medical therapy. Absolute risk differences in comparison to medical therapy for CABG (17.0%) and PCI (11.3%) were greater for patients > or =80 years of age than for younger patients. CONCLUSIONS: Elderly patients paradoxically have greater absolute risk reductions associated with surgical or percutaneous revascularization than do younger patients. The combination of these results with a recent randomized trial suggests that the benefits of aggressive revascularization therapies may extend to subsets of patients in older age groups.

Aged↗

PubMed2002

Sex differences in access to coronary revascularization after cardiac catheterization: importance of detailed clinical data.

BACKGROUND: Although some studies suggest that access to cardiac procedures may differ by sex, others have found no evidence of gender bias in cardiac care. OBJECTIVE: To study rates of percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery in men and women after cardiac catheterization. DESIGN: Cohort study with prospective data collection. SETTING: Alberta, Canada. PATIENTS: Persons undergoing cardiac catheterization between 1 January 1995 and 31 December 1998 (n = 21 816). MEASUREMENTS: The occurrence of revascularization procedures (PCI or CABG) in the year after cardiac catheterization was measured. Unadjusted revascularization rates, partially adjusted rates (adjusted for clinical variables available in most databases, including administrative databases), and fully adjusted rates (additionally adjusted for extent of coronary artery disease and ejection fraction) were also evaluated. RESULTS: The unadjusted relative risk was 0.67 (95% CI, 0.65 to 0.71) for the end point of any revascularization in women relative to men. The relative risk increased to 0.69 (CI, 0.66 to 0.72) with partial adjustment and to 0.98 (CI, 0.94 to 1.03) with full adjustment, indicating equivalent access to revascularization for men and women. For PCI, the corresponding relative risks were 0.77 (CI, 0.73 to 0.82), 0.84 (CI, 0.80 to 0.89), and 1.02 (CI, 0.96 to 1.08). For CABG surgery, the relative risks were 0.54 (CI, 0.51 to 0.58), 0.51 (CI, 0.48 to 0.55), and 0.93 (CI, 0.87 to 1.01). CONCLUSIONS: In Alberta, Canada, clinical variables fully explain sex differences in rates of revascularization after cardiac catheterization, and misleading conclusions would arise without full adjustment for clinical differences between men and women. Extreme caution is needed in interpreting reports on access to care that use sparsely detailed clinical data sources.

Alberta↗

PubMed2002

Multiple imputation versus data enhancement for dealing with missing data in observational health care outcome analyses.

The problem of missing data is frequently encountered in observational studies. We compared approaches to dealing with missing data. Three multiple imputation methods were compared with a method of enhancing a clinical database through merging with administrative data. The clinical database used for comparison contained information collected from 6,065 cardiac care patients in 1995 in the province of Alberta, Canada. The effectiveness of the different strategies was evaluated using measures of discrimination and goodness of fit for the 1995 data. The strategies were further evaluated by examining how well the models predicted outcomes in data collected from patients in 1996. In general, the different methods produced similar results, with one of the multiple imputation methods demonstrating a slight advantage. It is concluded that the choice of missing data strategy should be guided by statistical expertise and data resources.

Alberta↗

PubMedDate not supplied

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. DISCUSSION: 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.

Alberta↗

PubMedDate not supplied

Prognostic relevance of census-derived individual respondent incomes versus household incomes.

BACKGROUND: Census-based measures of income derived from median income of a geographic area are often used in health research. Many national census surveys gather information on both the respondent's individual income and the income for the entire household, giving researchers a choice of census income measures. We compared the extent to which individual respondent income and household income (both obtained from census data) are associated with outcomes in a cohort of patients with cardiac disease. METHODS: We used data from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH), where postal codes were linked to the Postal Code Conversion File (PCCF) to determine each patient's census Dissemination Areas (DA). DA-derived median household income and median individual income were obtained from the 2001 Canadian Census and survival outcomes were then directly determined for income groupings defined by quintile. Two-year survival adjusted for age and sex was described with a proportional hazards analysis. RESULTS: There were 9,397 patients undergoing cardiac catheterization between January 1, 2001 and March 31, 2002, with complete DA-level median income measures. Household income quintiles yielded a wider spread of survival across quintiles (range of 2-year estimated survival, 91.8% to 95.9% for household income versus 92.8% to 95.6% for respondent income), as well as a more progressive decline in survival as income decreased. This progressive decline was not seen for the respondent income measure. CONCLUSIONS: The greater spread and progressive decline of survival for household income relative to respondent income leads us to conclude that household income is the better socio-economic determinant of health in our data and for the outcome measure we studied.

Aged↗