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Biomedical subjects

K C Carrière

Publications and source records attributed to K C Carrière.

10 recordsLinked to original sources

Strategies for analysing missing item response data with an application to lung cancer.

Missing data problems persist in many scientific investigations. Although various strategies for analyzing missing data have been proposed, they are mainly limited to data on continuous measurements. In this paper, we focus on implementing some of the available strategies to analyze item response data. In particular, we investigate the effects of popular missing data methods on various missing data mechanisms. We examine large sample behaviors of estimators in a simulation study that evaluates and compares their performance. We use data from a quality of life study with lung cancer patients to illustrate the utility of these methods.

Aged↗

The role of proxy information in missing data analysis.

This article investigates the role of proxy data in dealing with the common problem of missing data in clinical trials using repeated measures designs. In an effort to avoid the missing data situation, some proxy information can be gathered. The question is how to treat proxy information, that is, is it always better to utilize proxy information when there are missing data? A model for repeated measures data with missing values is considered and a strategy for utilizing proxy information is developed. Then, simulations are used to compare the power of a test using proxy to simply utilizing all available data. It is concluded that using proxy information can be a useful alternative when such information is available. The implications for various clinical designs are also considered and a data collection strategy for efficiently estimating parameters is suggested.

Canada↗

An improved CML estimation procedure for the Rasch model with item response data.

Ordinal response data are commonly observed in health and medical investigations that include several items. The primary goal in the modelling of item response data is to find a unique measurement of the person's abilities and of the item difficulties that satisfies the properties of the fundamental measurement. One such analytic method in item response theory is the Rasch measurement, which is a way to convert ordinal observations into linear measures. Current estimation strategies assume the independence of the Rasch model parameters. In this paper, based on the conditional maximum likelihood, we implemented a simultaneous estimation method that can compare the Rasch parameters more efficiently. We also obtained the asymptotic properties of these estimators and developed the conditional likelihood ratio test for the goodness-of-fit of the model. Simulation studies were used to demonstrate the improved performance of our estimators as compared to that of currently used conditional method known as the CON procedure. We conclude that our estimation method outperforms CON in both model fit and the precision of the Rasch estimators.

Computer Simulation↗

A measure of continuity of care based on the multiplicative intensity model.

Continuity of care is a concept that is frequently used to measure patient satisfaction and other benefits provided by the health care system. Although several measures of continuity of care are used, most are built on unrealistic assumptions about random visits to providers and do not utilize all available information. In this paper we advocate stochastic processes to model continuity of care, and we propose a new measure of provider continuity based on the multiplicative intensity model. Using data on hypertensive patients in the province of Alberta, Canada, we demonstrate the utility of our method that incorporates ways to accommodate covariate information. Compared to the currently popular method, the proposed method in this paper is shown to assess both concentration of care aspects and other visit-based characteristics of the care being provided.

Adult↗

Variations in treatment of femoral neck fractures in Alberta.

OBJECTIVES: To examine, in the province of Alberta, temporal trends, regional variations in treatment options and in-hospital death rates after a femoral neck fracture. DESIGN: A retrospective cohort study. PATIENTS: Six years' data were abstracted from the Alberta Morbidity File, the Alberta Health Stakeholder File and the Alberta Health Care Claims File. Patients were included if they were Alberta residents, aged 65 years or older, had sustained a femoral neck fracture and had undergone internal fixation, hemiarthroplasty or total hip arthroplasty. MAIN OUTCOME MEASURES: Death rates, arthroplasty rates and hospital stay. RESULTS: In-hospital death rates were similar across hospitals, with risks being higher for men, patients aged 80 years or older and those with more comorbid conditions. Arthroplasty rates varied from 58% to 77% among hospitals, and hospital stays associated with arthroplasty were significantly longer than those associated with internal fixation. The chance of undergoing arthroplasty varied from hospital to hospital by gender and by the number of comorbid conditions. CONCLUSION: Regional variations suggest lack of agreement among Alberta's surgeons as to how best to treat femoral neck fractures.

Aged↗

Factors influencing the frequency of visits by hypertensive patients to primary care physicians in Winnipeg.

BACKGROUND: As part of a recent project focused on needs-based planning for generalist physicians, the authors documented the variety of practice styles of primary care physicians for managing patients with hypertension. They investigated the validity of various explanations for these different styles and the relative contributions of physician and patient characteristics to the rates at which hypertensive patients contact physicians. METHODS: Retrospective descriptive study using regression analyses to simultaneously adjust for the influence of key patient and physician characteristics. Hypertensive patients in Winnipeg were identified using Manitoba physician claims data for fiscal years 1993/94 and 1994/95. Patients were included if they were 25 years of age or more and had at least one physician contact in both 1993/94 and 1994/95 during which hypertension was diagnosed. In addition, the primary care physician had to be the physician that the patient contacted most frequently in 1993/94 and 1994/95 and with whom she or he had at least 2 visits during this period. Only patients of family practitioners whose practice included at least 50 hypertensive patients were included. RESULTS: To control for the effects of large samples and to validate the results, the authors conducted all analyses for half (6282) the sample of hypertensive patients who met the study criteria (12,563). A total of 132 primary care physicians who met the study criteria were identified. The patients made on average 9.3 ambulatory visits to physicians (both general practitioners and specialists) in 1994/95. Those who had more complex medical conditions (i.e., were formally referred to a specialist), those who had 3 or more serious medical problems and those who had been admitted to hospital made more visits to their primary care physician than those without these characteristics. After these and other key patient characteristics were controlled for, a primary care physician's patient recall rate in 1993/94 was strongly related to the number of visits his or her hypertensive patients made to all doctors for any reason in 1994/95. Physicians with high patient recall rates (i.e., who saw their hypertensive patients on average 8 or more times) in 1993/94 also had high recall rates in 1994/95. INTERPRETATION: Because patient characteristics most strongly associated with high visit rates were those reflecting patient illness, policy measures aimed at patients (e.g., user fees and deinsurance) do not appear to be the appropriate policy tool for dealing with high visit rates. Given the influence of a physician's patient recall rate on patient visit patterns, physician profiling and feedback may prove more appropriate.

Adult↗

Needs-based planning: the case of Manitoba.

OBJECTIVE: To illustrate the use of needs-based planning in the identification of physician surpluses and deficits and of resource misallocations within a provincial medical system at a time when provincial governments and medical associations across the country are faced with funding constraints for physician services. DESIGN: For each of 4 regions in Manitoba, the authors analysed residents' rates of physician visits (whether within the resident's own or another region). Residents' need for physician contact was estimated by means of a statistical analysis of the data on contacts in relation to age, sex and health-related indicators, and the rates of visits needed and actually made were compared. PARTICIPANTS: All Manitoba residents. OUTCOME MEASURES: Numbers of generalist physicians (general practitioners, family physicians, general internists and general pediatricians) needed to serve each region, and the extent of physician surplus and deficit in each region. RESULTS: There appeared to be a surplus of physicians in most of urban Manitoba but deficits in northern Manitoba and some parts of the rural south. General internists and general pediatricians in Winnipeg provide a significant part of the ambulatory care that is provided by general practitioners in other parts of the province. The provincial government currently spends more per resident to provide physician services in areas of physician surplus than in areas of physician deficit, although the patterns are inconsistent. CONCLUSIONS: Needs-based planning is possible. If provinces are intent on controlling physician numbers and expenditures, it makes sense to manage the implications of doing so.

Health Resources↗

Inappropriate hospital use by patients receiving care for medical conditions: targeting utilization review.

OBJECTIVE: To describe characteristics associated with inappropriate hospital use by patients in Manitoba in order to help target concurrent utilization review. Utilization review was developed to reduce inappropriate hospital use but can be a very resource-intensive process. DESIGN: Retrospective chart review of a sample of adult patients who received care for medical conditions in a sample of Manitoba hospitals during the fiscal year 1993-94; assessment of patients at admission and for each day of stay with the use of a standardized set of objective, nondiagnosis-based criteria (InterQual). PATIENTS: A total of 3904 patients receiving care at 26 hospitals. OUTCOME MEASURES: Acute (appropriate) and nonacute (inappropriate) admissions and days of stay for adult patients receiving care for medical conditions. RESULTS: After 1 week, 53.2% of patients assessed as needing acute care at admission no longer required acute care. Patients 75 years of age or older consumed more than 50% of the days of stay, and 74.8% of these days of stay were inappropriate. Four diagnostic categories accounted for almost 60% of admissions and days, and more than 50% of those days of stay were inappropriate. Patients admitted through the emergency department were more likely to require acute care (60.9%) than others (41.7%). Patients who were Treaty Indians had a higher proportion of days of stay requiring acute care than others (45.9% v. 32.8%). Patients' income and day of the week on admission (weekday v. weekend) were not predictive factors of inappropriate use. CONCLUSION: Rather than conducting a utilization review for every patient, hospitals might garner more information by targeting patients receiving care for medical conditions with stays longer than 1 week, patients with nervous system, circulatory, respiratory or digestive diagnoses, elderly patients and patients not admitted through the emergency department.

Adolescent↗

Family members' care expectations, care perceptions, and satisfaction with advanced cancer care: results of a multi-site pilot study.

Psychometric properties of assessment tools designed for use with English-speaking family members of advanced cancer patients in different care settings and different geographic locations were evaluated in this study. The robustness of the theoretical framework guiding the study and the factors identified with care satisfaction were also tested. Seventy-two family members drawn equally from medical hospital units, palliative care units, and home care programs in Alberta, Saskatchewan, and Manitoba participated. Instruments used included the F-Care Expectations Scale, F-Care Perceptions Scale, FAMCARE Scale, and the General Functioning Scale of the Family Assessment Device. All four tools yielded acceptable reliability estimates. Discrepancy theory predicted family care satisfaction in a highly significant manner (p < 0.0001). Family members of patients who had been diagnosed for longer than two years had more positive perceptions of palliative care than did family members of patients diagnosed for less than two years (p = 0.05). Older family members reported better family functioning than younger family members (p < 0.001). Spouses reported less discrepancy between care expectations and perceptions than did other relatives (p < 0.05).

Aged↗

Population health and health care use: an information system for policy makers.

University-based researchers in Manitoba, Canada, have used administrative data routinely collected as part of the national health insurance plan to design a population-based health information system (POPULIS). Decision-makers can use this system to make critical comparisons across regions of residents' health status, socioeconomic risk characteristics, and use of hospitals, nursing homes, and physicians. Policy makers have found this information system useful in providing answers to questions they are often asked: Which populations need more physician services? Which need fewer? Are high-risk populations poorly served or do they have poor health outcomes despite being well served? Does high utilization represent overuse or is it related to high need? Three commentaries follow.

Database Management Systems↗