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Biomedical subjects

L L Roos

Publications and source records attributed to L L Roos.

At least 55 records · Page 3Linked to original sources
PubMed1993

Trends in physician-diagnosed asthma prevalence in Manitoba between 1980 and 1990.

We attempted to assess recent changes in the prevalence of physician-diagnosed asthma and the possible influence of diagnostic exchange on these trends. The routinely collected data of the provincial Health Insurance Plan (physicians' claims) were used to determine the annual prevalence of physician-diagnosed asthma in Manitoba. Results indicate that the prevalence of physician-diagnosed asthma increased for all age groups in both male and female subjects between 1980 and 1990. The average increases were the highest in the age group 5 to 14 years for both sexes. The average increases varied with age and there were significant differences between the two sexes. There was evidence of increasing diagnostic exchange, that is, a tendency to label patients with asthma instead of alternative diagnoses. This was particularly prominent in those younger than 35 years of age. However, the increased prevalence of physician-diagnosed asthma, even for the younger population, cannot be fully explained by diagnostic exchange.

Adolescent↗
PubMed1992

Disparity between influenza vaccination rates and risks for influenza-associated hospital discharge and death in Manitoba in 1982-1983.

OBJECTIVE: To determine, in a defined population, the percentage of persons who were discharged from a hospital or died of influenza-associated respiratory conditions who had a health care contact during the preceding vaccination season and to determine the relation between risk status for influenza-associated hospitalization and death and influenza vaccination rates. DESIGN: An observational study using linked-record analysis of medical claims data. SETTING AND PATIENTS: A probability sample of 100,000 noninstitutionalized adults living in Manitoba in 1982 to 1983. MEASUREMENTS: Analysis of medical claims for influenza vaccination and hospital discharges and deaths for influenza-associated respiratory conditions during the 1982-83 influenza vaccination season and influenza outbreak period. RESULTS: For the population as a whole, 50% to 60% of elderly persons (greater than or equal to 65 years of age) and 30% to 40% of younger persons had one or more health care contacts during the influenza vaccination season but fewer than 10% of all persons had been discharged from a hospital. In contrast, for elderly persons hospitalized with respiratory conditions during the influenza outbreak period, approximately 80% had at least one health care contact during the vaccination season. Among the elderly, 39% to 46% of all those discharged for influenza-associated respiratory conditions and 62% to 67% of those who died had been discharged from hospital during the previous vaccination season. Persons discharged with high-risk conditions during the vaccination season were at greater risk for hospitalization with influenza-associated respiratory conditions but were less likely to be vaccinated than were those at lower risk. CONCLUSIONS: Most persons who were hospitalized with influenza-associated respiratory conditions had contact with health care providers during the preceding influenza vaccination season. Among elderly patients, previous hospital care was common, especially among those who died. The disparity between influenza vaccination rates and risks for influenza-associated hospital discharge and death supports a strategy of hospital-based influenza vaccination.

Adult↗
PubMed1991

Comparing clinical information with claims data: some similarities and differences.

How well can hospital discharge abstracts be used to estimate patient health status? This paper compares information on comorbidity obtained from hospital discharge abstracts for patients undergoing prostatectomy or cholecystectomy at a Winnipeg teaching hospital with clinical data on preoperative medical conditions prospectively collected during an Anesthesia Follow-up study. The diagnostic information on cardiovascular disease, respiratory disease, and metabolic disorders showed considerable agreement, ranging from 65 to over 90% correspondence across the two data sets. Certain conditions noted by the anesthesiologist were often absent from the claims data; cardiovascular disease was recorded in the clinical data but absent from the claims for 31% of prostatectomy and 17% of cholecystectomy cases. Such patients were less likely to have been assigned a high score on the ASA Physical Status measure or to have high-risk diagnoses on the hospital file. Similar findings resulted from comparing the two sources in their ability to predict such adverse outcomes as mortality and readmission to hospital: the anesthesia file generally included less serious comorbidity.

Anesthesiology↗
PubMed1991

Record linkage strategies. Part I: Estimating information and evaluating approaches.

Record linkage techniques can help identify the same patient for matching diverse files (hospital discharge abstracts, insurance claims, registries, Vital Statistics data) which contain similar identifiers. Prior knowledge of whether a linkage is feasible is important to prevent wasted effort (additional data collection or data manipulation), which decreases the cost-effectiveness of the linkage. Using examples generated by linking the Manitoba Health Services Commission data with Vital Statistic files, a method of estimating the information in each data set is presented first. Further, the feasibility of several different record linkage strategies is described and tested, given varying amounts of information. At the margin, relatively small amounts of information (having just one more variable to match with) can make a great difference. Probabilistic linkage's great advantage was found in those situations where only a moderate amount of extra information was available. By using the above techniques when working with one or both files in a proposed record linkage project, a much more informed judgement can now be made as to whether a linkage will or will not work. In facilitating record linkage, flexibility of both software and the strategy for matching is very important.

Data Collection↗
PubMed1991

Record linkage strategies: Part II. Portable software and deterministic matching.

Software to perform record linkage should have several characteristics: (1) portability in being able to function with researchers' current arrangement of computer systems and languages, (2) flexibility in handling different linkage strategies, and (3) low cost in both computer time and researchers' efforts. A linkage package (LINKS) is described which satisfies these criteria; LINKS provides tools for both deterministic and probabilistic linkage as well as test modules for assessing data quality and structure. Because each linkage project is different, the modular nature of the software allows for better control of the programming process and development of unique strategies. Since the user provides the weights and decision rules, he may modify data between steps and/or develop extra steps to supplement the basic modules. In two information-rich linkage projects involving California AIDS data, LINKS identified mortality using deterministic approaches and permitted comparisons with other software and strategies. Flexible software and a deterministic approach would have eliminated the expensive key entry used to add full names and social security numbers as additional identifiers to one of the California data files.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The incidence of fracture of the proximal femur in two million Canadians from 1972 to 1984. Projections for Canada in the year 2006.

Reported increases in the number of fractures of the proximal femur in Europe are greater than can be explained by demographic changes alone. This trend was assessed in Canada by examining hospital discharge records from the provinces of Saskatchewan and Manitoba from 1972 to 1984. The annual number of first fractures of the proximal femur in persons older than 50 years of age increased 59.7% in women and 42.2% in men during this time period. In most of the five-year age groups the percentage of increase in the number of fractures exceeded the percentage of increase in population of that age group. Annual age-specific incidences (by five-year age groups) increased exponentially with age, doubling every six years, and reached a maximum value of 4% in women older than 90 years of age. Annual age-adjusted incidences increased significantly over the study period in men and women. For the whole of Canada in 1987, it is estimated that there were 13,193 first fractures of the proximal femur in women and 4610 in men, and that in the year 2006 these will rise to 22,922 and 7846, respectively. The actual increase will be considerably greater if the age-specific incidences continue to increase as they have from 1972 to 1984. The gradual decline in physical activity, which contributes to bone loss, may be one etiological factor of this trend during the last half century.

Age Factors↗
PubMed1990

Postsurgical mortality in Manitoba and New England.

Per capita hospital expenditures in the United States exceed those in Canada, but little research has examined differences in outcomes. We used insurance databases to compare postsurgical mortality for 11 specific surgical procedures, both before and after adjustment for case mix, among residents of New England and Manitoba who were over 65 years of age. For low- and moderate-risk procedures, 30-day mortality rates were similar in both regions, but 6-month mortality rates were lower in Manitoba. For the two high-risk procedures, concurrent coronary bypass/valve replacement and hip fracture repair, both 30-day and 6-month mortality rates were lower in New England. Although no consistent pattern favoring New England for cardiovascular surgery was found, the increased mortality following hip fracture in Manitoba was found for all types of repair and all age groups. We conclude that for low- and moderate-risk procedures, the higher hospital expenditures in New England were not associated with lower perioperative mortality rates.

Aged↗
PubMed1990

Outcomes and quality assurance: facilitating the use of administrative data.

To evaluate quality of care, a two-step approach seems appropriate. First, highly-structured explicit criteria, based on patient outcomes such as mortality, readmissions, or unusually long lengths of hospital stay, might help identify adverse events using routinely-collected discharge data. Then, process criteria might be used for subsequent medical record reviews to determine whether a quality problem exists. Large administrative data bases suggest the possibility of developing an epidemiology of quality of care; understanding how quality problems are distributed across the hospitals in a province seems feasible. Population-wide data are essential for comprehensive follow-up and for effective studies of medical practices. Hospital-based follow-up can miss important events; we found the relative percentage of short-term readmissions to hospitals other than the hospital of surgery startling. However, hospital-based data can sometimes be used in place of the more costly and harder-to-generate population data for quality monitoring. For example, in examining correlations among various outcome indicators following five common surgical procedures, we found the ranking of hospitals according to inhospital mortality to be highly correlated with their ranking according to 30-day post-surgical mortality.

Data Collection↗
PubMed1990

Managing scarce services. A waiting list approach to cardiac catheterization.

Relatively little attention has been directed to the provision of health care services when demand exceeds availability. Since "waiting lists" are characteristic of the delivery of cardiovascular services in Manitoba, we hypothesized that the highest priority would be given to cases with the greatest urgency. This study examined the waiting lists for cardiac catheterization in one of two tertiary health care facilities offering comprehensive cardiovascular care to a population of slightly more than one million persons. Hospital records of all patients undergoing cardiac catheterization from May 1981 through December 1982 were abstracted retrospectively. For 871 patients entering a catheterization laboratory by two different routes (Elective Care, N = 557; Immediate Care, N = 314), patient need for immediate catheterization was assessed. Clinical differences between patients in the two groups were striking. Immediate Care patients more frequently had acute congestive heart failure, prior aortic valve surgery, and chronic obstructive pulmonary disease. Immediate Care patients were most frequently in Class 4 of the NYHA functional classification and were more often treated with triple medical therapy. These clinically ill individuals were more likely to enter the hospital via the Emergency Room; they were more likely to have long hospital stays and to die in hospital. As implemented in one Manitoba hospital, the waiting list process appears to have worked fairly well; cardiac arrest, acute myocardial infarction, and death among patients waiting for catheterization were all rare events. Both those patients needing immediate care and those who could wait with a low probability of a poor outcome were successfully identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1989

Hospital care for elderly patients with diseases of the circulatory system. A comparison of hospital use in the United States and Canada.

In an effort to determine how lower health care expenditures in Canada as compared with the United States translate into actual hospital services received, we examined discharge rates, lengths of stay, and the case-mix index (calculated from diagnosis-related group weights) for those 65 years of age and older hospitalized with cardiovascular disease in the United States and two Canadian provinces, Manitoba and Ontario, in 1981 and 1985. We expected that the effect of the prospective payment system might be reflected in changes between 1981 and 1985. Discharge rates for medical treatment of cardiovascular diseases were 2.9 percent higher in the United States than in Canada in 1981, but 1.8 percent lower in 1985; however, the case-mix index was 3.0 percent lower in 1981 and 4.8 percent higher in 1985. The case-mix index for combined medical and surgical discharges was 5.0 percent lower in the United States in 1981, but 10.7 percent higher in 1985. U.S. surgical discharge rates were 20 percent lower in 1981, but 20 percent higher in 1985. Rates of coronary bypass surgery were much higher in the United States in both years, but increased rapidly in both countries, particularly among those 75 and older. Elderly Canadians appeared to have access to cardiovascular surgery, with the exception of coronary bypass surgery, and to other hospital care for cardiovascular disease similar to that of elderly people in the United States.

Aged↗
PubMed1989

Assessing data quality: a computerized approach.

With the growing reliance on large health care data bases, the need to verify data quality increases as well. Because of the considerable costs involved in checks using primary data collection, a computerized methodology for performing such checks is suggested. The technique seems appropriate for any situation where two data collection systems (i.e. hospital discharge abstracts and physician claims for payment) relate to the same event, such as a patient's hospitalization. After reviewing other approaches, this paper suggests linking physician claims for performing particular surgical procedures with hospital discharge abstracts for the stay in which the surgery took place. Physician and hospital data for adults age 25 and over in Manitoba from 1 April, 1979 to 31 March, 1984 were used to address the questions: 1. How well can the two data sets be linked? 2. Given linkage of the two data sets, how much agreement is there as to procedure and diagnosis? Linkage between hospital and physician data was excellent (over 95%) for 5 out of 11 surgical procedures (hysterectomy, prostatectomy, total hip replacement, coronary artery bypass surgery, and heart valve replacement); there was over 90% perfect agreement for three other procedures (cholecystectomy, cataract surgery and total knee replacement). Problems with matching the Manitoba Health Services Commission tariffs (on physician claims) with ICD-9-CM operation codes (on hospital data) led to only 77% perfect agreement for vascular surgery and 84% for gallbladder and biliary tract operations other than cholecystectomy; over 10% of the cases linked on surgeon and date but not on the designated procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Data Collection↗
PubMed1989

Risk adjustment in claims-based research: the search for efficient approaches.

Claims-based indices of comorbidity and severity, as well as other measures derived from routinely collected administrative data, are developed and tested. The extent to which risk adjustments using claims can be improved by adding information from one well-known measure based on chart review and patient examination (the American Society of Anesthesiologists' (ASA) Physical Status score) is also examined. Readmissions and mortality after three common surgical procedures are the outcomes studied using multiple logistic regression. Claims-based measures of comorbidity, derived both from hospital discharge abstracts at the time of surgery and from hospitalizations in the 6 months before surgery, provided reasonably good predictions of postsurgical readmissions and mortality. In the most complete logistic regression models, the Somers' Dyx measure of fit (a rank correlation coefficient) ranged from 0.23 to 0.38 for readmissions and from 0.46 to 0.72 for mortality. In 5 out of 6 cases, these predictions were not improved by including the prospectively-collected ASA Physical Status score. Such difficulties in improving risk adjustment by more intensive data collection are discussed in terms of their research implications.

Comorbidity↗
PubMed1989

Nonexperimental data systems in surgery.

This article reviews nonexperimental data bases, emphasizing the present uses and future opportunities of routinely collected information. Data bases are discussed in terms of appropriate research designs. Possibilities for expanding available information through new data collection and through record linkage are stressed. The relationship of nonexperimental data systems to randomized trials and to clinical decision-making is examined.

Cohort Studies↗
PubMed1989

Innovation, centralization, and growth. Coronary artery bypass graft surgery in Manitoba.

Innovation and diffusion of new surgical procedures are limited in Manitoba, Canada by restrictions on which hospitals are allowed to perform particular surgical programs. Programs centralizing performance of certain operations in a few hospitals have the potential for controlling costs and quality of care but may limit access for individuals living in other areas. Such issues are highlighted in this analysis of coronary artery bypass graft surgery in Manitoba. Patterns of growth and access are first examined; then regional variations in rates of bypass surgery are compared with rates for coronary angiography and valve surgery. Physician reluctance to refer patients to Winnipeg appears to be responsible for the lower rates of these procedures in Western Manitoba. The implications for studies of centralization/regionalization of medical services, physician decision-making, and diffusion of technology are explored.

Adult↗
PubMed1988

Becoming more efficient at outcomes research.

This paper discusses several practical problems in research design: Is it worth doing a relatively "quick and dirty" study or is a more thorough study using all available information necessary? All the desired information may either not be available or be time-consuming to collect. What are the likely biases in going ahead and doing the research with the data base "in hand"? Such issues are important because of the limited resources for technology assessment (in terms of money, number of researchers, and research interest) and the great number of unstudied technologies.

Cholecystectomy↗
PubMed1988

Using administrative data to predict important health outcomes. Entry to hospital, nursing home, and death.

This paper assesses our ability to use administrative data for developing indicators of health status. Traditionally, measures of health status have been derived from interviews. Here indicators from administrative data and from interviews are compared, i.e., their ability to predict important health outcomes for a large representative sample of elderly residents of Manitoba, Canada. Indicators of health status derived from an administrative data system and from health interviews are shown to provide roughly similar predictions of nursing-home entry. Administrative data provide significantly better predictions of death and future hospital entry than do variables from interview data.

Aged↗