Biomedical subjects

A Wajda

Publications and source records attributed to A Wajda.

12 recordsLinked to original sources

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↗

PubMed1992

Assessing physicians' compliance with guidelines for Papanicolaou testing.

In this study, population-based data were used to examine the appropriateness of Papanicolaou (Pap) testing from the perspective of the women being tested and their physicians. The approach used is unique in its assessment of overtesting and undertesting in the primary care setting. From the data base of the province of Manitoba's universal health insurance plan, 4-year health histories (1981 to 1984) were constructed for each woman from a random sample of the population of women who, in 1982, were between the ages of 25 to 64 years (n = 22,287). At the last visit to a general practitioner, gynecologist, or general surgeon in 1984 (termed the current visit), the authors determined whether a Pap test was given for each woman. Using decision rules from a Canadian task force report on cervical screening and previous health history, the authors evaluated the appropriateness of screening by determining whether a Pap test was given and was needed, or whether a women who had not received a Pap test required one. Overall, 55.7% of women were tested appropriately. Of the 5352 women who received a Pap test at the current visit, 62.8% were overtested. Of the 16,935 women not tested at the current visit, 38.5% required screening (i.e. were undertested). Characteristics of a physician's practice that were significantly related to compliance with the guidelines included having a high proportion of patients visiting for obstetric or gynecologic reasons. Variables that were associated with negative compliance were 1) being a gynecologist; and 2) having a high proportion of patients who lived in inner city or rural areas. Because physicians are paid a fee for every Pap smear taken and the guidelines were well disseminated, these results should be reasonably representative of fee-for-service practice in North America, where preventive care is not subject to user charges. This study supports previous findings that a passive approach to dissemination of guidelines is insufficient to effect practice.

Adult↗

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↗

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↗

PubMed1987

Software for health care analysts: a modular approach.

The many concerns about the cost and quality of health care suggest the need to facilitate planners' using existing data bases for utilization review, program evaluation, and technology assessment. Despite both the availability of relevant data and widespread improvements in computing power, integrated computer software to permit analyses by nonspecialists has not previously been developed. This paper discusses the features of a health policy information system which aids working with hospital discharge abstracts, medical claims, cancer registries, and vital statistics files. Analyses of small area utilization, length of stay, in-hospital mortality, and readmissions are facilitated by this package. This information system, named the Health Applications System, includes an analysis module, three information management modules, and a set of record linkage modules. The modules were developed using the macroprocessor in the fourth-generation SAS system. Features of the software and their implications for data analysis are discussed.

Data Interpretation, Statistical↗

PubMed1987

Simplifying record linkage: software and strategy.

Although the methodology of record linkage is fairly well developed, there is a need for less expensive methods and simpler software to facilitate trying out different tactics to generate good linkages. The present work has built on a fourth generation language SAS (Statistical Analysis System) with accompanying macroprocessor, to develop a user-friendly and flexible system for both exact and probabilistic matching. The major features of the LINKS system are presented and illustrated using 1979-1984 information from the Manitoba Health Services Commission (MHSC) registry file with the Canadian Mortality Data Base. Initial runs with exact, then probabilistic, matching linked approximately 91% of the Vital Statistics records to corresponding MHSC records. Subsequent modification of parameters improved the linkage to 95%.

Database Management Systems↗

PubMed1986

The art and science of record linkage: methods that work with few identifiers.

Increasing use of administrative records for research purposes has led to the need to develop methods for linking records. Linkage of the data from the Manitoba Health Services Commission (MHSC) with Canadian Vital Statistics records was done to verify Manitoba deaths, to measure degree of agreement between the two data sets, and to link "cause of death" information from Vital Statistics back to medical histories. A multi-stage approach to matching was adopted. Individual records matching perfectly across a number of relevant variables in the two files were selected first, reducing the number of records going through the probability matching to manageable proportions. Overall, almost 96% of the MHSC records were well matched with Vital Statistics records. Both uses of the matched data and various ways to confirm data quality are discussed.

Humans↗

PubMed1986

Variations in physicians' hospitalization practices: a population-based study in Manitoba, Canada.

This paper uses claims data from a universal health care system to describe physicians' hospitalization styles after adjusting for case-mix characteristics of their primary patients. Patients were uniquely assigned to that physician (general or family practitioners, internist, general surgeon, or obstetrician/gynecologist) seen most frequently over each two two-year periods (1972-74 and 1974-76). Four indices were developed including: 1) percentage of primary patients hospitalized; 2) mean number of readmissions for such patients; 3) mean length of stay; and 4) total days of hospitalization per primary care patient (a summary measure combining the first three). Rates of admission, not length of stay, were shown to be strongly related to this summary measure. Marked variations in the hospitalization indices were observed across physicians; these variations cannot be explained by the health or sociodemographic characteristics of a physician's patients. Rural physicians practicing in areas with high bed-to-population ratios and low occupancy rates were particularly high users of hospitals. The economic implications of different practice styles are shown to be large; physicians who were high users of hospitals serve 27 per cent of the patients but their patients consume 42 per cent of the hospital days.

Adult↗

PubMedDate not supplied

Is there a role for surgery in the acute management of infective endocarditis? A decision analysis and medical claims database approach.

In the absence of good clinical evidence from a randomized trial, the authors performed a decision analysis to determine the potential value of early elective surgery (OPNOW) for patients with left-sided Staphylococcus aureus infective endocarditis. Initial impressions (before performance of decision analysis) and initial runs at the formal models using probability estimates derived from clinicians suggested that OPNOW (i.e., within a few days of starting antibiotics) offered no advantage over attempted medical cure (WAIT) (life expectancy: WAIT = 325 weeks; OPNOW = 255 weeks). Extensive sensitivity analyses identified critical variables that needed further empirical estimation. The Manitoba Health Services Commission database identified 127 incident cases of endocarditis between April 1, 1979, and March 31, 1985, enabling estimation of values for these critical variables. With these estimates, the early surgery strategy appeared much better than the previous analyses had suggested (life expectancy: WAIT = 208 weeks, OPNOW = 256 weeks). The authors believe that this approach of combining decision analysis with medical claims databases is useful as an alternative or precursor to randomized trials, especially where the resource requirements and logistic difficulties of performing randomized trials are great.

Adult↗