Peter C Austin
Datos Biográficos
| ID | 5147702 |
|---|---|
| NOMBRE | Peter C Austin |
| NOMBRES | Peter C |
| APELLIDO | Austin |
| FIRMA | AUSTIN P C |
| AFILIACIONES | University of Toronto |
| ORCID | 0000-0003-3337-233X |
| VERIFICADO | Sí |
| TOTAL DE OBRAS | 47 |
| TOTAL DE CITAS | 121 |
| TOTAL COMO AUTOR | 47 |
| TOTAL COMO EDITOR | 0 |
| PRIMER AÑO DE PUBLICACIÓN | 1981 |
| AÑO MÁS RECIENTE DE PUBLICACIÓN | 2024 |
| ÍNDICE H | 5 |
Change in Hospital Risk-Standardized Stroke Mortality Performance With and Without the Passive Surveillance Stroke Severity Score
BACKGROUND: Adjustment for baseline stroke severity is necessary for accurate assessment of hospital performance. We evaluated whether adjusting for the Passive Surveillance Stroke SeVerity (PaSSV) score, a measure of stroke severity derived using administrative data, changed hospital-specific estimated 30-day risk-standardized mortality rate (RSMR) after stroke. METHODS: We used linked administrative data to identify adults who were hospitalized…
Rising out-of-hospital mortality in Canada during 2020‒2022
Comorbidity-stratified estimates of 30-day mortality risk by age for unvaccinated men and women with Covid-19
The mortality risk in COVID-19 increases with age and comorbidity but the prognostic implications varied by sex and condition. These observations can support communication efforts and inform vaccine rollout in jurisdictions with limited vaccine supplies
Variation and Correlation of Potential Unintended Consequences of Antipsychotic Reduction in Ontario Nursing Homes Over Time
BACKGROUND: Potentially inappropriate antipsychotic use has declined in nursing homes over the past decade; however, increases in the documentation of relevant clinical indications (eg, delusions) and the use of other psychotropic medications have raised concerns about diagnosis upcoding and medication substitution. Few studies have examined how these trends over time vary across and within nursing homes, information that may help to support anti…
Trends in Health Service Use for Canadian Adults With Dementia and Parkinson Disease During the First Wave of the Covid-19 Pandemic
In this population-based repeated cross-sectional study in Ontario, Canada, those with dementia, those with PD, and older adults sought hospital care far less than usual, were not admitted to nursing homes, and experienced excess mortality during the first wave of the pandemic. Most services returned to historical levels, but virtual physician visits remained a feature of care. While issues of equity and quality of care are still emerging among p…
Missing Data in Clinical Research
Missing data is a common occurrence in clinical research. Missing data occurs when the value of the variables of interest are not measured or recorded for all subjects in the sample. Common approaches to addressing the presence of missing data include complete-case analyses, where subjects with missing data are excluded, and mean-value imputation, where missing values are replaced with the mean value of that variable in those subjects for whom it…
Estimating the Net Benefit of Improvements in Hospital Performance
BACKGROUND: It is important to be able to estimate the anticipated net population benefit if the performance of hospitals is improved to specific standards. OBJECTIVE: The objective of this study was to show how G-computation can be used with random effects logistic regression models to estimate the absolute reduction in the number of adverse events if the performance of some hospitals within a region was improved to meet specific standards. RESE…
Neighbourhood walkability and the incidence of diabetes
BACKGROUND: People living in highly walkable neighbourhoods tend to be more physically active and less likely to be obese. Whether walkable urban design reduces the future risk of diabetes is less clear. METHODS: We used inverse probability of treatment weighting to compare 10-year diabetes incidence between residents living in high-walkability and low-walkability neighbourhoods within five urban regions in Ontario, Canada. Adults (aged 30-85 yea…
General and specific contextual effects in multilevel regression analyses and their paradoxical relationship
To be relevant for public health, a context (e.g., neighborhood, school, hospital) should influence or affect the health status of the individuals included in it. The greater the influence of the shared context, the higher the correlation of subject outcomes within that context is likely to be. This intra-context or intra-class correlation is of substantive interest and has been used to quantify the magnitude of the general contextual effect (GCE…
Intermediate and advanced topics in multilevel logistic regression analysis
Multilevel data occur frequently in health services, population and public health, and epidemiologic research. In such research, binary outcomes are common. Multilevel logistic regression models allow one to account for the clustering of subjects within clusters of higher-level units when estimating the effect of subject and cluster characteristics on subject outcomes. A search of the PubMed database demonstrated that the use of multilevel or hie…
The number of subjects per variable required in linear regression analyses
OBJECTIVES: To determine the number of independent variables that can be included in a linear regression model. STUDY DESIGN AND SETTING: We used a series of Monte Carlo simulations to examine the impact of the number of subjects per variable (SPV) on the accuracy of estimated regression coefficients and standard errors, on the empirical coverage of estimated confidence intervals, and on the accuracy of the estimated R(2) of the fitted model. RES…
Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies
The propensity score is defined as a subject's probability of treatment selection, conditional on observed baseline covariates. Weighting subjects by the inverse probability of treatment received creates a synthetic sample in which treatment assignment is independent of measured baseline covariates. Inverse probability of treatment weighting (IPTW) using the propensity score allows one to obtain unbiased estimates of average treatment effects. Ho…
The Effect of Multidisciplinary Heart Failure Clinic Characteristics on 1-Year Postdischarge Health Care Costs
BACKGROUND: Although multidisciplinary heart failure (HF) clinics are efficacious, it is not known how patient factors or HF clinic structural indicators and process measures have an impact on the cumulative health care costs. RESEARCH DESIGN: In this retrospective cohort study using administrative databases in Ontario, Canada, we identified 1216 HF patients discharged alive after an acute care hospitalization in 2006 and treated at a HF clinic. …
In Response
Institute for Clinical Evaluative Sciences Toronto, ON, Canada †Department of Epidemiology and Biostatistics, Michigan State University East Lansing, MI Supported by an operating grant from the Canadian Institutes of Health Research (CIHR). P.C.A. is also supported in part by a Career Investigator Award from the Heart and Stroke Foundation. The authors declare no conflict of interest
Administrative Hospitalization Database Validation of Cardiac Procedure Codes
BACKGROUND: Although cardiac procedures are commonly used to treat cardiovascular disease, they are costly. Administrative data sources could be used to track cardiac procedures, but sources of such data have not been validated against clinical registries. OBJECTIVES: To examine accuracy of cardiac procedure coding in administrative databases versus a prospective clinical registry. SAMPLE: We examined a total of 182,018 common cardiac procedures …
Using G-Computation to Estimate the Effect of Regionalization of Surgical Services on the Absolute Reduction in the Occurrence of Adverse Patient Outcomes
BACKGROUND: Numerous studies have found that increased hospital or surgeon operative volumes, as measured by the number of procedures performed, are associated with improved patient outcomes after surgery. These findings have been used to support important health policy decisions about regionalization of surgical services, in which provision of specific surgical services is restricted to hospitals that maintain operative volumes above a specified…
The Relationship Between the C-Statistic of a Risk-adjustment Model and the Accuracy of Hospital Report Cards
BACKGROUND: Hospital report cards, in which outcomes following the provision of medical or surgical care are compared across health care providers, are being published with increasing frequency. Essential to the production of these reports is risk-adjustment, which allows investigators to account for differences in the distribution of patient illness severity across different hospitals. Logistic regression models are frequently used for risk adju…
Using Ensemble-Based Methods for Directly Estimating Causal Effects
Researchers are increasingly using observational or nonrandomized data to estimate causal treatment effects. Essential to the production of high-quality evidence is the ability to reduce or minimize the confounding that frequently occurs in observational studies. When using the potential outcome framework to define causal treatment effects, one requires the potential outcome under each possible treatment. However, only the outcome under the actua…
Language Documentation
Language documentation, also known as documentary linguistics, is the subfield of linguistics that deals with creating multipurpose records of languages through audio and video recording of speakers and signers and with annotation, translation, preservation, and distribution of the resulting materials. It shows by its nature multidisciplinarity and draws on theoretical concepts and methods from linguistics, ethnography, folklore studies, psycholo…
Optimal caliper widths for propensity‐score matching when estimating differences in means and differences in proportions in observational studies
In a study comparing the effects of two treatments, the propensity score is the probability of assignment to one treatment conditional on a subject's measured baseline covariates. Propensity‐score matching is increasingly being used to estimate the effects of exposures using observational data. In the most common implementation of propensity‐score matching, pairs of treated and untreated subjects are formed whose propensity scores differ by at mo…
An Introduction to Propensity Score Methods for Reducing the Effects of Confounding in Observational Studies
The propensity score is the probability of treatment assignment conditional on observed baseline characteristics. The propensity score allows one to design and analyze an observational (nonrandomized) study so that it mimics some of the particular characteristics of a randomized controlled trial. In particular, the propensity score is a balancing score: conditional on the propensity score, the distribution of observed baseline covariates will be …
A Tutorial and Case Study in Propensity Score Analysis
Propensity score methods allow investigators to estimate causal treatment effects using observational or nonrandomized data. In this article we provide a practical illustration of the appropriate steps in conducting propensity score analyses. For illustrative purposes, we use a sample of current smokers who were discharged alive after being hospitalized with a diagnosis of acute myocardial infarction. The exposure of interest was receipt of smoki…
Predicting the Risk of 1-Year Mortality in Incident Dialysis Patients
BACKGROUND: Administrative databases are increasingly being used to study the incident dialysis population and have important advantages. However, traditional methods of risk adjustment have limitations in this patient population. OBJECTIVE: Our objective was to develop a prognostic index for 1-year mortality in incident dialysis patients using administrative data that was applicable to ambulatory patients, used objective definitions of candidate…
The Mortality Risk Score and the ADG Score
BACKGROUND: Logistic regression models that incorporated age, sex, and indicator variables for the Johns Hopkins' Aggregated Diagnosis Groups (ADGs) categories have been shown to accurately predict all-cause mortality in adults. OBJECTIVES: To develop 2 different point-scoring systems using the ADGs. The Mortality Risk Score (MRS) collapses age, sex, and the ADGs to a single summary score that predicts the annual risk of all-cause death in adults…
Using the Johns Hopkins Aggregated Diagnosis Groups (ADGs) to Predict Mortality in a General Adult Population Cohort in Ontario, Canada
BACKGROUND: Administrative healthcare databases are increasingly used for health services and comparative effectiveness research. When comparing outcomes between different treatments, interventions, or exposures, the ability to adjust for differences in the risk of the outcome occurring between treatment groups is important. Similarly, when conducting healthcare provider profiling, adequate risk-adjustment is necessary for conclusions about provi…
Forty Years on
Complex Sentence Constructions in Australian Languages
Over the past fifteen years, descriptions of Australian Aboriginal languages have provided important data for the typological study of morpho-syntactic phenomena. The present volume presents descriptions of complex sentence phenomena in ten Australian languages and provides important new material in this area of current concern in linguistics. Complex sentences are described either from a syntactic or from a semantic (discourse-functional) point …
Australian Linguistic Studies
Measuring Population Health
Cross-cultural Comparisons of Health Status in Canada Using the Health Utilities Index
Although the healthy immigrant effect is probably responsible for some of the variation in health status among cultural groups in Canada, considerable differences exist within the immigrant and Canadian-born populations. Cultural factors may have a substantial effect on the reporting of pain and mental health problems. Further studies are needed to determine the cross-cultural validity of the HUI
Neighbourhood walkability and the incidence of diabetes
BACKGROUND: People living in highly walkable neighbourhoods tend to be more physically active and less likely to be obese. Whether walkable urban design reduces the future risk of diabetes is less clear. METHODS: We used inverse probability of treatment weighting to compare 10-year diabetes incidence between residents living in high-walkability and low-walkability neighbourhoods within five urban regions in Ontario, Canada. Adults (aged 30-85 yea…
An Introduction to Multilevel Regression Models
Language Documentation
Language documentation, also known as documentary linguistics, is the subfield of linguistics that deals with creating multipurpose records of languages through audio and video recording of speakers and signers and with annotation, translation, preservation, and distribution of the resulting materials. It shows by its nature multidisciplinarity and draws on theoretical concepts and methods from linguistics, ethnography, folklore studies, psycholo…
Australian Linguistic Studies
Basic Materials in Wankumara (Galali)
Complex Sentence Constructions in Australian Languages
Over the past fifteen years, descriptions of Australian Aboriginal languages have provided important data for the typological study of morpho-syntactic phenomena. The present volume presents descriptions of complex sentence phenomena in ten Australian languages and provides important new material in this area of current concern in linguistics. Complex sentences are described either from a syntactic or from a semantic (discourse-functional) point …
Effects of Socioeconomic Status on Access to Invasive Cardiac Procedures and on Mortality after Acute Myocardial Infarction
BACKGROUND: Universal health care systems seek to ensure access to care on the basis of need rather than income and to improve the health status of all citizens. We examined the performance of the Canadian health system with respect to these goals in the province of Ontario by assessing the effects of neighborhood income on access to invasive cardiac procedures and on mortality one year after acute myocardial infarction. METHODS: We linked claims…
The use of the Tobit model for analyzing measures of health status
Measuring Population Health
Cross-cultural Comparisons of Health Status in Canada Using the Health Utilities Index
Although the healthy immigrant effect is probably responsible for some of the variation in health status among cultural groups in Canada, considerable differences exist within the immigrant and Canadian-born populations. Cultural factors may have a substantial effect on the reporting of pain and mental health problems. Further studies are needed to determine the cross-cultural validity of the HUI
An Introduction to Multilevel Regression Models
A brief note on overlapping confidence intervals
Factoring Socioeconomic Status Into Cardiac Performance Profiling for Hospitals
BACKGROUND: Critics of "scorecard medicine" often highlight the incompleteness of risk-adjustment methods used when accounting for baseline patient differences. Although socioeconomic status is a highly important determinant of adverse outcome for patients admitted to the hospital with acute myocardial infarction, it has not been used in most risk-adjustment models for cardiovascular report cards. OBJECTIVES: To determine the incremental impact o…
Forty Years on
Patient, Physician, and Community Factors Affecting Referrals to Specialists in Ontario, Canada
QUESTION ADDRESSED: This population-based study examines the factors affecting referrals by primary care physicians (PCPs) to specialists. MATERIALS AND METHODS: Multilevel Poisson models were used to test the impact of patient, physician and community-level variables on the referral rate (the number of office-based specialist referrals per patient by the patient's customary PCP in fiscal year 1997/98). Patients from each of 6972 PCPs with suffic…
Comparison of Coding of Heart Failure and Comorbidities in Administrative and Clinical Data for Use in Outcomes Research
BACKGROUND: Despite the potential usefulness of administrative databases for evaluating outcomes, coding of heart failure and associated comorbidities have not been definitively compared with clinical data. OBJECTIVE: To compare the predictive value of heart failure diagnoses and secondary conditions identified in a large administrative database with chart-based records. METHODS: The authors studied 1808 patient records sampled from 14 acute care…
Measuring the Effect of a Large Reduction in Welfare Payments on Mental Health Service Use in Welfare-Dependent Neighborhoods
BACKGROUND: Major social policy changes were implemented in Canada in the last decade with few efforts to examine their potential health effects. OBJECTIVES: We sought to determine the impact of a large reduction in welfare benefits on use of ambulatory physician mental health services in areas with high levels of welfare dependency relative to areas with low levels of welfare dependency. METHODS: The setting was Toronto, Canada. Data sources inc…
The Impact of Under Coding of Cardiac Severity and Comorbid Diseases on the Accuracy of Hospital Report Cards
CONTEXT: Hospital report cards usually are based on administrative discharge abstracts. However, cardiac severity and comorbidities generally are under-reported in administrative data. OBJECTIVE: We sought to determine how undercoding of cardiac severity and comorbidities affects the determination that some hospitals are high-mortality outliers. DESIGN: Simulations using retrospective data on 18,795 patients admitted with an acute myocardial infa…
Socioeconomic Status, Access to Health Care, and Outcomes After Acute Myocardial Infarction in Canada's Universal Health Care System
BACKGROUND: There is a debate as to whether universal drug coverage confers similar access to care at all socioeconomic status (SES) levels. Experiences in Canada may bring light to questions raised regarding access. OBJECTIVE: To assess associations between SES and access to cardiac care and outcomes in Canada's universal health care system. DESIGN, SETTING, AND PATIENTS: All patients admitted to acute care hospitals in Quebec (QC), Ontario (ON)…
A critical appraisal of propensity‐score matching in the medical literature between 1996 and 2003
Propensity‐score methods are increasingly being used to reduce the impact of treatment‐selection bias in the estimation of treatment effects using observational data. Commonly used propensity‐score methods include covariate adjustment using the propensity score, stratification on the propensity score, and propensity‐score matching. Empirical and theoretical research has demonstrated that matching on the propensity score eliminates a greater propo…
Balance diagnostics for comparing the distribution of baseline covariates between treatment groups in propensity‐score matched samples
The propensity score is a subject's probability of treatment, conditional on observed baseline covariates. Conditional on the true propensity score, treated and untreated subjects have similar distributions of observed baseline covariates. Propensity‐score matching is a popular method of using the propensity score in the medical literature. Using this approach, matched sets of treated and untreated subjects with similar values of the propensity s…
Using the Standardized Difference to Compare the Prevalence of a Binary Variable Between Two Groups in Observational Research
Researchers are increasingly using the standardized difference to compare the distribution of baseline covariates between treatment groups in observational studies. Standardized differences were initially developed in the context of comparing the mean of continuous variables between two groups. However, in medical research, many baseline covariates are dichotomous. In this article, we explore the utility and interpretation of the standardized dif…
Development of an Algorithm to Identify Preoperative Medical Consultations Using Administrative Data
BACKGROUND: Preoperative consultation by internal medicine specialists may help improve the care of patients undergoing major surgery. Population-based administrative data are an efficient approach for studying these consultations at a population-level. However, administrative data in many jurisdictions lack specific codes to identify preoperative medical consultations, as opposed to consultations for nonoperative indications. OBJECTIVE: To devel…
A Modification of the Elixhauser Comorbidity Measures Into a Point System for Hospital Death Using Administrative Data
BACKGROUND: Comorbidity measures are necessary to describe patient populations and adjust for confounding. In direct comparisons, studies have found the Elixhauser comorbidity system to be statistically slightly superior to the Charlson comorbidity system at adjusting for comorbidity. However, the Elixhauser classification system requires 30 binary variables, making its use for reporting and analysis of comorbidity cumbersome. OBJECTIVE: Modify t…
Using Administrative Datasets to Study Outcomes in Dialysis Patients
BACKGROUND: The use of administrative health data and other secondary data sources to conduct research are increasing, and the quality of these data requires careful scrutiny to ensure that findings of studies based on them are accurate. METHODS: We conducted a multicenter, chart-abstraction study in Ontario, Canada to evaluate the ability of linked administrative databases to identify important baseline demographic and treatment information, cha…
Optimal caliper widths for propensity‐score matching when estimating differences in means and differences in proportions in observational studies
In a study comparing the effects of two treatments, the propensity score is the probability of assignment to one treatment conditional on a subject's measured baseline covariates. Propensity‐score matching is increasingly being used to estimate the effects of exposures using observational data. In the most common implementation of propensity‐score matching, pairs of treated and untreated subjects are formed whose propensity scores differ by at mo…
An Introduction to Propensity Score Methods for Reducing the Effects of Confounding in Observational Studies
The propensity score is the probability of treatment assignment conditional on observed baseline characteristics. The propensity score allows one to design and analyze an observational (nonrandomized) study so that it mimics some of the particular characteristics of a randomized controlled trial. In particular, the propensity score is a balancing score: conditional on the propensity score, the distribution of observed baseline covariates will be …
A Tutorial and Case Study in Propensity Score Analysis
Propensity score methods allow investigators to estimate causal treatment effects using observational or nonrandomized data. In this article we provide a practical illustration of the appropriate steps in conducting propensity score analyses. For illustrative purposes, we use a sample of current smokers who were discharged alive after being hospitalized with a diagnosis of acute myocardial infarction. The exposure of interest was receipt of smoki…
Medicine (37 obras) · Statistics (22 obras) · Mathematics (21 obras) · Internal Medicine (19 obras) · Internal Medicine (18 obras) · Population (15 obras) · Computer Science (14 obras) · Emergency Medicine (14 obras) · Demography (13 obras) · Emergency Medicine (13 obras)