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.
Hospital discharge abstracts from Manitoba Health, used to study the changes in utilization rates over eight fiscal years (1989-1996).
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.
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.
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.
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.
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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.
This article explores the impact of the tonsillectomy operation using a large data base and several different approaches. The likely range of effects of the surgery and various threats to validity are studied from a quasi-experimental perspective. Information on possible patient self-selection for tonsil surgery is provided. Selection is dealt with from another viewpoint by comparing the outcomes of patients under the care of physicians having a "high propensity to operate" with those going to physicians who tend to operate less. Finally, a computer simulation studies the extent to which the measured results of tonsil surgery might be explained by particular selection mechanisms working in conjunction with random processes of episode generation. The "savings" in respiratory episodes estimated by the various approaches ranges from 0.1 episodes to approximately 0.8 episode for the year following surgery.
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)
An overview of the Manitoba study of common surgical procedures is presented. The research is oriented toward describing and explaining the outcomes of nine relatively common procedures, using longitudinal data from the Manitoba Health Services Commission's population registry, medical claims, and physician claims. The research approach recognizes differences among surgical procedures, tailoring the analyses to specific characteristics of a given procedure. At the same time, this article describes the efforts made to achieve economies of scale in organizing the data base and writing the computer programs. The strategy used for assessing surgical risks and benefits is described at some length. Health services utilization before and after surgery is compared across small areas with widely differing surgical rates. Comparisons between surgical and other groups are suggested. The wealth of data permits a number of different types of studies. One study deals with patterns of surgical practice, types of operations performed, and risk characteristics of patients brought to surgery in areas with differing surgical rates. High-risk patients residing in high-rate areas are more likely to be operated upon than their counterparts in low-rate areas. A second study found that hysterectomy is apparently being used in situations where women have high rates of contact with the health care system before surgery; their rates of contact after surgery are almost as high. Ongoing activities in the research project are outlined.
This paper explores outcomes associated with the tonsillectomy operation using multiple control groups and a large claims-based data bank from the Canadian province of Manitoba. Given the difficulty of conducting large-scale clinical trials of common surgical procedures, the use of multiple methods for evaluating such interventions is both advocated and implemented in this study. When the data are restricted to respiratory diagnoses, the findings suggest that, on the average, tonsil surgery saves between one half and one and a half episodes of illness per patient over the two years after surgery. Such savings are much more pronounced among individuals having several tonsillitis episodes in the preoperative year. However, when all medical claims are considered, the estimated savings from the tonsillectomy operation are somewhat reduced. Individual variation in predisposition to "see the doctor" appears to account for such results; visits about conditions other than respiratory take up much of the "savings" produced by tonsil surgery. The findings are discussed in terms of the costs and benefits of the tonsillectomy operation, and future research needs are outlined.
To assess whether the objectives of a new Extended Care Unit were reflected in the care of the patients and in the outcome of that care, an audit of the patients' records was performed. The audit sample involved 101 geriatric patients who had been admitted to the Unit for rehabilitation therapy, and then discharged. The study included assessment of the records for compliance with individual audit criteria, examination of the records in terms of a composite audit score, and analysis of the relationship between these scores and three outcome indices. Although the audit did not show a significant correlation between recorded care processes and treatment outcomes, it did reveal the extent to which the Unit's goals were reflected in the care process.
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.
This study concentrates on utilizing registries and assessing their quality for population-based research. A method of successive comparisons is used to develop and update a summary record of coverage (length of time on the registry) and mortality for each individual in the Manitoba Health Services Commission data base. Various ways to ascertain the accuracy of the summary records are discussed. These techniques are validated by efforts to follow over an 8-year period 4,794 individuals interviewed in 1971 as part of ongoing research on the Manitoba elderly. Ninety-seven percent of the total elderly sample (and 99% of those successfully matched with interviewees) were traced over 8 years. Deaths recorded on hospital claims but not on the master registry and possible unrecorded out-of-hospital deaths are outstanding problems with the Manitoba data base. Further checks against 1970-1977 vital statistics information in the Canadian Mortality Data Base will be made.