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Biomedical subjects

L L Roos

Publications and source records attributed to L L Roos.

At least 19 recordsLinked to original sources
PubMed2004

A framework for modelling differences in regional mortality over time.

STUDY OBJECTIVE: To present a conceptual framework for testing differences in mortality for small geographical areas over time using the generalised linear model with generalised estimating equations. This framework can be used to test whether the magnitude of regional inequalities in health status has changed over time. DESIGN: A Poisson regression model for correlated data is used to investigate the relation of population health status to demographic, geographical, and temporal explanatory variables. Differences between regions at one or more points in time are tested with linear contrasts. SETTING AND PARTICIPANTS: A case example shows the application of the framework. All cause mortality and cause specific mortality were compared for three rural regions of Manitoba, Canada between 1985 and 1999. The data were obtained from Vital Statistics records and the provincial health registry. MAIN RESULTS: Tests of linear contrasts on the regression coefficients for time and region show an increase in the magnitude of the difference in the risk of all cause mortality and heart disease mortality between northern and southern regions of the province for the 1985-1989 and 1995-1999 time periods. No significant differences are identified for cancer, injury, or respiratory disease mortality. CONCLUSIONS: The proposed framework enables testing of a variety of hypotheses about differences between regions and time periods and can be applied to other measures of population health status.

Health Status↗
PubMed2001

Monitoring health reform: a report card approach.

UNLABELLED: During the past several years, budget cuts have forced hospitals in several countries to change the way they deliver care. Gilson (Gilson, L. (1998). DISCUSSION: In defence and pursuit of equity. Social Science & Medicine, 47(12), 1891-1896) has argued that, while health reforms are designed to improve efficiency, they have considerable potential to harm equity in the delivery of health care services. It is essential to monitor the impact of health reforms, not only to ensure the balance between equity and efficiency, but also to determine the effect of reforms on such things as access to care and the quality of care delivered. This paper proposes a framework for monitoring these and other indicators that may be affected by health care reform. Application of this framework is illustrated with data from Winnipeg, Manitoba, Canada. Despite the closure of almost 24% of the hospital beds in Winnipeg between 1992 and 1996, access to care and quality of care remained generally unchanged. Improvements in efficiency occurred without harming the equitable delivery of health care services. Given our increasing understanding of the weak links between health care and health, improving efficiency within the health care system may actually be a prerequisite for addressing equity issues in health.

Adolescent↗
PubMed2001

Epidemiology of varicella zoster virus infection in Canada and the United Kingdom.

Many countries are currently studying the possibility of mass vaccination against varicella. The objective of this study was to provide a comprehensive picture of the pre-vaccine epidemiology of the varicella zoster virus (VZV) to aid in the design of immunization programs and to adequately measure the impact of vaccination. Population-based data including physician visit claims, sentinel surveillance and hospitalization data from Canada and the United Kingdom were analysed. The key epidemiological characteristics of varicella and zoster (age specific consultation rates, seasonality, force of infection, hospitalization rates and inpatient days) were compared. Results show that the overall epidemiology of varicella and zoster is remarkably similar between the two countries. The major difference being that, contrary to Canada, the epidemiology of varicella seems to be changing in the United Kingdom with an important decrease in the average age at infection that coincides with a significant increase in children attending preschool. Furthermore, differences exist in the seasonality between the United Kingdom and Canada, which seem to be primarily due to the school calendar. These results illustrate that school and preschool contact patterns play an important role in the dynamics of varicella. Finally, our results provide baseline estimates of varicella and zoster incidence and morbidity for VZV vaccine effectiveness and cost-effectiveness studies.

Adolescent↗
PubMed2000

Health reform and technological change: shifting hospitalization patterns for four procedures in Manitoba.

This study used Manitoba data from 1991 to 1996 to assess the effects of health reforms and technological advances on hospitalization patterns, patient mortality, and readmission rates. Cholecystectomy and hernia repair served as indicators of response to both new technology and health reforms, while appendectomy and hysterectomy helped gauge the impact of health reforms alone. Neither the introduction of new technology (i.e. laparoscopy) nor the health reform initiatives (i.e. shorter hospital stays) adversely affected surgical volumes, postsurgical mortality, or postsurgical readmissions.

Health Care Reform↗
PubMed2000

Health care seeking behavior following a health survey: impact on prevalence estimates of chronic diseases.

This article addresses the time sequence between a population health survey and subsequent health care use and how this changes the incidence estimates of selected chronic diseases. A cardiovascular survey of a representative sample of the adult population of Manitoba, Canada was linked with the health insurance claims database. Of the 2792 subjects in the survey, 98% were linked successfully, using an encrypted personal health insurance number. Five years of physician claims data for the survey participants were reviewed including 18 months prior to and 42 months following the survey. Survey participants started seeking confirmation of possible hypertension as soon as they received blood pressure information at the interview. Confirmation of diabetes and elevated cholesterol were not completed until 3-4 months after participants had received the laboratory test results. As many as 4.6 times more new cases of hypertension per month, 5.1 times more cases of elevated cholesterol, and 3.3 times more cases of diabetes were diagnosed following the survey. Surveys designed to determine the prevalence of specific chronic diseases generate new cases within a short time afterwards, thus affecting the original prevalence estimates. The process of assessing the burden of disease in a population is dynamic rather than static, and comparisons across populations need to take into account the frequency and recency of past surveys.

Adult↗
PubMed2000

Multiple approaches to assessing the effects of delays for hip fracture patients in the United States and Canada.

OBJECTIVE: To examine the determinants of postsurgery length of stay (LOS) and inpatient mortality in the United States (California and Massachusetts) and Canada (Manitoba and Quebec). DATA SOURCES/STUDY SETTING: Patient discharge abstracts from the Agency for Health Care Policy and Research Nationwide Inpatient Sample and from provincial health ministries. STUDY DESIGN: Descriptive statistics by state or province, pooled competing risks hazards models (which control for censoring of LOS and inpatient mortality data), and instrumental variables (which control for confounding in observational data) were used to analyze the effect of wait time for hip fracture surgery on postsurgery outcomes. DATA EXTRACTIONS: Data were extracted for patients admitted to an acute care hospital with a primary diagnosis of hip fracture who received hip fracture surgery, were admitted from home or the emergency room, were age 45 or older, stayed in the hospital 365 days or less, and were not trauma patients. PRINCIPAL FINDINGS: The descriptive data indicate that wait times for surgery are longer in the two Canadian provinces than in the two U.S. states. Canadians also have longer postsurgery LOS and higher inpatient mortality. Yet the competing risks hazards model indicates that the effect of wait time on postsurgery LOS is small in magnitude. Instrumental variables analysis reveals that wait time for surgery is not a significant predictor of postsurgery length of stay. The hazards model reveals significant differences in mortality across regions. However, both the regressions and the instrumental variables indicate that these differences are not attributable to wait time for surgery. CONCLUSIONS: Statistical models that account for censoring and confounding yield conclusions that differ from those implied by descriptive statistics in administrative data. Longer wait time for hip fracture surgery does not explain the difference in postsurgery outcomes across countries.

Aged↗
PubMed2000

Across time and space: variations in hospital use during Canadian health reform.

OBJECTIVES: To investigate change in hospital utilization in a population and to discuss analytical strategies using large administrative databases, focusing on variations in rates of different types of hospital utilization by income quintile neighborhoods. DATA SOURCES: Hospital discharge abstracts from Manitoba Health, used to study the changes in utilization rates over eight fiscal years (1989-1996). STUDY DESIGN: We test the hypotheses that health reform has changed utilization rates, that utilization rates differ significantly across income quintiles (defined by the relative affluence of neighborhood of residence), and that these variations have been maintained over time. Our approach uses generalized estimating equations to produce robust and consistent results for studying rates of recurrent and nonrecurrent events longitudinally. DATA EXTRACTION METHODS: Rates of individuals hospitalized, hospital discharges, days of hospitalization, and hospitalization for different types of medical conditions and surgical procedures are generated for the period April 1, 1989 through March 31, 1997 for residents of Winnipeg, Manitoba. Data are grouped according to the individual's age, gender, and neighborhood of residence on April 1 of each of the eight fiscal years for the rate calculations. Neighborhood of residence and the 1991 Canadian Census public use database are used to assign individuals to income quintiles. PRINCIPAL FINDINGS: The substitution of outpatient surgery for inhospital surgery accounted for much of the change in hospital utilization over the 1989-1996 period. Health care reform did not have a significant effect on the utilization gradient already observed across socioeconomic groups. Health reform markedly accelerated declines in in-hospital utilization. CONCLUSIONS: Grouping the data with key characteristics intact facilitates the statistical analysis of utilization measures previously difficult to study. Such analyses of variations across time and space based on parametric models allows adjustment for continuous covariates and is more efficient than the traditional nonparametric approach using standardized rates.

Adolescent↗
PubMed1999

A research registry: uses, development, and accuracy.

Many studies of population health, clinical epidemiology, and health services can be supported by a population-based research registry. Such a registry accurately defines the health insurance status for each individual over many years, magnifying the effectiveness of a cross-sectional registry (typically relevant for only a short duration) used in the administration of a health insurance plan. A research registry can distinguish between "well" individuals (no contact with the health care system), loss to follow-up (ineligibility associated with leaving the insurance plan), loss of continuity (two or more unlinked registrations over time for the same person), and mortality. The Manitoba research registry was developed to facilitate longitudinal studies; working within strict confidentiality controls, identifiers for each individual known to Manitoba Health since 1970 can be retrieved and a single unique identifier assigned. Careful reporting of changes in family registration numbers has enabled tracing area of residence, marital status, and family characteristics; results are equivalent to a daily census of the province. This article provides details on source materials, design, and quality of the registry, highlighting its value both for the development of integrated population health information systems and for research in general.

Adolescent↗
PubMed1999

Managing health services: how the Population Health Information System (POPULIS) works for policymakers.

OBJECTIVES: University-based researchers in Manitoba, Canada, have used administrative data routinely collected as part of the national health insurance plan to design an integrated database and population-based health information system. This information system is proving useful to policymakers for answering such questions as: 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? More specifically, this system provides decision makers with the capability to make critical comparisons across regions and subregions of residents' health status, socioeconomic risk characteristics and use of hospitals, nursing homes, and physicians. The system permits analyses of demographic changes, expenditure patterns, and hospital performance in relation to the population served. The integrated database has also facilitated outcomes research across hospitals and countries, utilization review within a single hospital, and longitudinal research on health reform. The discussion highlights the strengths of integrated population-based information in analyzing the health care system and raising important questions about the relationship between health care and health.

Community Health Planning↗
PubMed1999

Delivering prevention: the role of public programs in delivering care to high-risk populations.

A successful program of prevention or early detection should have a high level of population coverage and should ensure that high-risk populations are targeted. In practice, relatively little attention has been paid to the tendency toward greater use of preventive care by populations at lower risk, in other words, for higher use by the wealthy than by the poor. Current delivery patterns of preventive care raise questions as to how to organize these services more effectively. Physician-based delivery of preventive care in a fee-for-service system seems to result in Canadian patterns of use that are fairly similar to those found in the United States. Universal free insurance alone does not appear to be enough to counteract the failure to target preventive care toward the least-healthy groups. Appropriately-run Canadian provincial programs may be able both to expand coverage and to target high-risk populations. The population coverage for three measures directed toward prevention or early detection--childhood immunization (which in Manitoba has been offered through a long-standing provincial program), screening mammography (a new provincial program), and cervical cancer screening (no provincial program)-are compared using longitudinal administrative data from Manitoba. The discussion emphasizes the role of provincial programs and the possibilities for using population-based data to help provide cost-effective care to high-risk populations.

Adolescent↗
PubMed1998

Managing health services: how administrative data and population-based analyses can focus the agenda.

University-based researchers in Manitoba, Canada, have used administrative data routinely collected as part of the national health insurance plan to design an integrated database and population-based health information system. This information system is proving useful to policymakers for providing answers to such questions as: 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 utilization related to high need? More specifically, this system provides decision-makers with the capability to make critical comparisons across regions and subregions of residents' health status, socioeconomic risk characteristics, and use of hospitals, nursing homes, and physicians. The system permits analyses of demographic changes, expenditure patterns, and hospital performance in relation to the population served. The integrated database has also facilitated outcomes research across hospitals and counties, utilization review within a single hospital, and longitudinal research on health reform. A particularly interesting application to planning physician supply and distribution is discussed. The discussion highlights the strengths of integrated population-based information in analyzing the health care system and raising important questions about the relationship between health care and health.

Canada↗
PubMed1997

Age-specific education and income gradients in morbidity and mortality in a Canadian province.

While important age-related trends in the use of health care services over the past two decades in Canada have been well described, a comprehensive description of socioeconomic gradients in morbidity and mortality across age cohorts for a representative population has not been accomplished to date in Canada. The objective of this study was to describe age-specific socioeconomic differentials in mortality and morbidity for a representative sample of a single Canadian province. The study sample was formed from the linkage of individual respondent records in the 1986 census to vital statistics records and comprehensive records of health care utilization for a 5% sample of residents of the province of Manitoba. Using two measures of socioeconomic status derived from census responses, attained education and household income, individuals were stratified into age-specific quartile ranks. Based on diagnostic information contained on health care utilization records, the proportion of the sample in treatment during a 12-month observation period was calculated for 15 broadly defined categories of morbidity and tested for differences across socioeconomic quartiles. Mortality was inversely associated with both income and education quartile rank. In the analysis of morbidity, no association between socioeconomic status and treatment prevalence was observed in the majority, no association between socioeconomic status and treatment prevalence was observed in the majority of the 122 age- and disorder-specific strata tested. Of the observed associations, however, negative relationships were dominant, indicating a higher treatment prevalence among individuals of lower attained education or lower household income. Across the age course, negative relationships were most frequently present among young and middle aged adults, those aged 30-64, and were more consistently found for income than for education. The general findings of this study of a representative Canadian population support observations from other developed country settings that socioeconomic differences in relative rates of mortality and morbidity over the life course are greatest in the adult years.

Adolescent↗
PubMed1997

Comparison of survey and physician claims data for detecting hypertension.

Using linked data from the Manitoba (Canada) Heart Health Survey (MHHS) and physician service claims files we assessed the degree to which self-reported hypertension and clinically measured hypetension agreed with physician claims hypertension, and examined the likely sources of disagreement. The overall agreement between survey and claims data for hypertension detection was moderate to high: 82% (kappa = 0.56) for self-reported and physician claims hypertension, and 85% (kappa = 0.60) for clinically measured and physician claims hypertension. In the comparison between self-report and physician claims, those who were classified as obese, diabetic, or a homemaker were significantly more likely to have a hypertension measure not confirmed by the other. Disagreement between clinically measured and physician claims was also more common among the obese and homemakers, as well as those on medication for heart diseases, elevated cholesterol levels (LDL), and 35 years of age and older. The high overall level of agreement among these three measures suggest that each may be used with confidence as an indication of hypertension; however, the agreement appears lower among individuals presenting a more complicated clinical profile.

Adult↗
PubMed1997

A method of comparison for standardized rates of low-incidence events.

The authors present an approximate but simple approach to comparing age-gender standardized rates of low-incidence events (mortality or morbidity) rates across several geographic areas. The presented method will be useful particularly when a person-level database, one that includes unique person identifiers, is not available. We specify conditions under which comparisons can be made without calculating empirical standard errors and worrying unduly about recurrent events. To compare indirectly standardized rates, only information on the size, the crude rate, and the standardized rate of the areas are needed. For comparing directly standardized rates, which requires stratum-specific rates, the method also requires stratum-specific total numbers of events and individuals but does not require person-level information. The proposed approach builds on previous work comparing rates using person-level data.

Coronary Angiography↗
PubMed1997

Estimating the burden of disease. Comparing administrative data and self-reports.

OBJECTIVES: A cardiovascular health survey of a representative sample of the adult population of Manitoba, Canada was combined with the provincial health insurance claims database to determine the accuracy of survey questions in detecting cases of diabetes, hypertension, ischemic heart disease, stroke, and hypercholesterolemia. METHODS: Of 2,792 subjects in the survey, 97.7% were linked successfully using a scrambled personal health insurance number. Hospital and physician claims were extracted for these individuals for the 3-year period before the survey. RESULTS: The authors found no benefits to using restrictive criteria for entrance into the study (ie, requiring more than one diagnosis to define a case). Using additional years of data increased agreement between data sources. Kappa values indicated high levels of agreement between administrative data and self-reports for diabetes (0.72) and hypertension (0.59); kappa values were approximately 0.4 for the other conditions. Using administrative data as the "gold standard," specificity was generally very high, although cases with hypertension and hypercholesterolemia (diagnosed primarily by laboratory or physical measurement) were associated with a lower specificity than the other conditions. Sensitivity varied markedly and was lowest for "other heart disease" and "stroke". For diabetes and hypertension, inclusion criteria calling for more than one diagnosis reduced the accuracy of case identification, whereas increasing the number of years of data increased accuracy of identification. For diabetes and hypertension, self-reports were fairly accurate in detecting "true" past history of the illness based on physician diagnosis recorded on insurance claims. CONCLUSIONS: This study demonstrates the feasibility of linking a large health survey with administrative data and the validity of self-reports in estimating the prevalence of chronic diseases, especially diabetes and hypertension. A linked data set offers unusual opportunities for epidemiologic and health services research in a defined population.

Adolescent↗
PubMed1997

Income level and asthma prevalence and care patterns.

Manitoba has a universally accessible health-care system that records physician contacts and hospitalizations in such a way that they can be ascribed to individuals. We examined the prevalence of physician-diagnosed asthma, bronchitis, and airways obstruction (total respiratory morbidity [TRM]) in Winnipeg in 1988 and 1992, using place of residence to divide people into quintiles according to average family income. Physician office visits, hospitalizations, and consultation referrals were each examined. Three age groups: 0 to 14 yr, 15 to 34 yr, and > or = 35 yr were studied. The prevalence of TRM was greater in low- than in high-income quintiles. Asthma prevalence was unrelated to income in the younger age groups; in the older group asthma was more common in low-income groups, but was less strongly related to income than was TRM. Asthma prevalence increased over the years studied, but the increase was not related to income level. There was some evidence of income-related diagnostic bias in that low-income patients were more likely to be labeled with a related diagnosis in addition to asthma than were high-income patients. Low-income patients had more physician contacts than did high-income patients. In terms of physician office visits, care continuity did not differ among income quintiles. Low-income quintiles had more hospitalizations than did high-income quintiles, and differences were larger than could be accounted for by diagnostic bias; asthma was probably more severe in low-income quintiles. High-income quintiles had more consultation referrals than did low-income quintiles.

Adolescent↗
PubMed1997

Complications, comorbidities, and mortality: improving classification and prediction.

OBJECTIVE: First, to compare the distribution of complications and comorbidities associated with 17 common surgical procedures. We then describe the effect of augmenting an ICD-9-CM version of the Charlson comorbidity index, given the possible confounding of comorbidities and complications, for three common inpatient surgical procedures: coronary artery bypass surgery, pacemaker surgery, and hip fracture repair. DATA SOURCES AND STUDY SETTING: Individuals having one of the above procedures between April 1, 1990 and March 31, 1994, identified from Manitoba Health hospital discharge data, and their extracted records. STUDY DESIGN: Design was cross-sectional and longitudinal using Manitoba data on hospital utilization and mortality. DATA COLLECTION/EXTRACTION: Manitoba hospital discharge abstracts permit identifying whether or not the diagnosis represents an in-hospital complication of care. Two data sets were created for each procedure, one including complication diagnoses and another with complications removed. PRINCIPAL FINDINGS: The degree to which complications contaminated estimation of comorbidity depended both on the procedures studied and on the covariates selected. The unique structure of the algorithm for the Charlson comorbidity index led to complication diagnoses having only a minor effect on the comorbidity score generated. Unless a data set affords the opportunity to remove complication diagnoses, the improvement in comorbidity detection afforded by augmenting the Charlson index, combined with the potential for overestimation of comorbidity, seem sufficiently modest to contraindicate such augmentation.

Algorithms↗