Comparison of risk and patterns of practice in patients older and younger than 70 years with acute myocardial infarction in a two-year period (1987-1989)

To further evaluate contemporary risk and practice patterns in acute myocardial infarction (AMI), 402 consecutive patients with AMI between July 1, 1988, and June 30, 1989 were studied. The clinical investigations, medical therapy and outcome of patients aged greater than or equal to 70 years (n = 132; group 1) were compared with patients aged less than 70 years (n = 270; group 2). In group 1, 20% of patients had no typical cardiac pain versus 6% in group 2 (p less than 0.01). History of previous AMI, Q-wave AMI and peak creatine kinase were not different in the 2 groups. In-hospital mortality was markedly higher in group 1 (27%) than in group 2 (8%), p less than 0.01. Multivariate analysis revealed previous AMI, presentation without typical pain and age greater than or equal to 70 years to be independently associated with the greatest relative risk. Post-AMI exercise testing, ejection fraction calculations and coronary angiography were all performed less often (p less than 0.01); proven effective medical therapies, including thrombolysis, beta blockers, acetylsalicylic acid and nitrates were all used less frequently (p less than 0.01). The very high mortality and less aggressive management of elderly patients with AMI confirm similar data from our 1987 AMI patient cohort and other recently reported AMI patient outcome analyses. However, it remains uncertain why older patients with AMI are investigated and treated differently from younger patients. Further studies are warranted.

Mortality risk and patterns of practice in 2,070 patients with acute myocardial infarction, 1987-92. Relative importance of age, sex, and medical therapy.

OBJECTIVE: To define contemporary age- and sex-related mortality risks and patterns of medical practice in acute myocardial infarction (AMI). DESIGN: Retrospective comparison of demographic and clinical variables, including the use of proven effective AMI medical therapy, among AMI patients cohorts from 1987 to 1992. PATIENTS/SETTING: Of a total of 2,070 AMI patients, 629 were women and 1,441, men; 951 patients were managed in university hospitals, 641 in a regional hospital, and 478 in community hospitals. INTERVENTIONS: No direct study interventions; results of practice patterns and risk analyses of the earlier (1987-90) AMI cohorts, however, were published concurrently with the actual practices of the more recent (1991-92) cohorts and may have had some indirect effect on the recent practice patterns. RESULTS: Univariate analysis showed that mortality was higher (p < 0.0001) and use of thrombolysis, beta blockers, and acetylsalicylic acid was lower (p < 0.0001) in patients 70 years of age and older, compared with younger patients, and in women, compared with men. Multivariate analysis of the entire patient sample revealed age of 75 years or older (154 percent) and age 70 to 74 years (141 percent) to be associated with the highest relative risk of death in hospital. The increased relative risk associated with previous AMI was 45 percent. Acetylsalicylic acid use was associated with the greatest decrease in relative risk of death (-69 percent), followed by beta blockers (-36 percent) and thrombolysis (-31 percent). These patterns of relative risk were the same for men and women. CONCLUSIONS: Among contemporary AMI patients, advanced age and female sex are associated with relative under-utilization of proven effective medical therapy and increased risk of dying in the hospital. Although the contribution of age to AMI risk appears greater than that of gender, survival in any high risk group would likely be improved by increased use of proven medical therapy.

The use of bed distribution and service population indexes for hospital bed allocation.

To provide an empirical base for bed reallocation within a hospital planning jurisdiction in Canada, this article proposes a population-based method to measure the distribution of acute care beds for each district and the service load for each hospital. The measure for the bed distribution (BDI) is the number of beds per 1,000 age-sex-adjusted number of residents in a district, while the service load of a hospital is measured by the number of persons being served per bed (SPI). The number of beds allocated to each district, or the number of persons served by each hospital, was estimated by applying the hospital service population model, which employs both relevance- and commitment-index methods. The method thus proposed was applied to Alberta data. It appears that both BDI and SPI measures are stable across the variation of methods or data sources, yet sensitive enough to detect changes over the years. Using these indexes, potentially over- or underbedded districts and over- or underloaded hospitals can be identified for further investigation so that possible reallocation of acute care beds among the hospitals may take place.

Mortality risk factors associated with mitral valve replacement: a survival analysis of 10 year follow-up data.

The primary purpose of this study was to evaluate the long term performance of several prosthetic cardiac valves and the influence on outcome of different surgeons by following 328 patients for up to 10 years after mitral valve replacement surgery in a tertiary care centre. This type of follow-up study is faced with severe methodological difficulties, as mortality and complications after surgery can be influenced not only by preoperative clinical status but also by the competence of the operating surgeons, the type of prosthesis used, and system-related variables such as the overall quality of nursing care. The primary statistical models used were life-table analysis, logistic regression and Cox's proportional hazard regression, employing prosthesis type, surgeon and other patient- or system-specific variable as covariates. The relative performance of valve prostheses and surgeons were assessed for short and long term survival. Biologic and Omniscience valves outperformed others for short and long term survival, while Lillehei-Kaster valves performed well for short term but not long term survival. The results also suggest that the performance levels of surgeons do vary, and the choice of surgeon could be a significant risk factor in a given medical centre.

Long term clinical outcomes following isolated mitral valve replacement.

OBJECTIVE: This study reviews the short and long term outcomes of patients who underwent isolated mitral valve replacement at the University of Alberta Hospitals during the past decade. DESIGN: Data were obtained retrospectively by review of patients' hospital charts, cardiologists' follow-up charts, contact with patients' physicians, and direct telephone or mail contact with patients and/or their surviving relatives. RESULTS: The clinical outcomes of 198 consecutive patients (124 women and 74 men) who underwent isolated mitral valve replacement from January 1981 to December 1990 at the University of Alberta Hospital were reviewed. Overall early operative mortality was 11%. Deaths were mainly related to pump failure and previous mitral valve replacement. Late mortality was 17%. Follow-up data were available except in five patients. Average follow-up was 6.3 years. Overall cumulative survival was 72.9 +/- 3.4% at five years and 63.1 +/- 4.8% at 10 years. The cumulative freedom from complications was 64.3 +/- 3.9% and 36.4 +/- 4.9% at five and 10 years, respectively. Long term survival rates obtained after isolated mitral valve replacement are higher than those reported in series of medically treated patients with mitral valve disease. CONCLUSIONS: Mitral valve replacement can prolong survival as well as improve symptoms in patients with symptomatic mitral valve disease.

Changes in acute myocardial infarction risk and patterns of practice for patients older and younger than 70 years, 1987-90.

OBJECTIVE: To evaluate temporal changes in risk and patterns of hospital practice for acute myocardial infarction (AMI). DESIGN/PATIENTS: Retrospective analysis of age-related medical therapy and outcome of 342 consecutive patients (132 at least 70 years old and 210 younger than 70) with AMI between July 1, 1989, and June 30, 1990, and comparison with data from two previous analyses of AMI practice in 1987 (n = 207) and 1988-89 (n = 402). SETTING: Tertiary care medical centre. INTERVENTIONS: No direct interventions; results of the two previous AMI practice pattern analyses, however, were propagated during the practice time of the most recent analysis. RESULTS: In 1989-90, hospital mortality was higher (19%) among patients at least 70 years old compared with patients younger than 70 (8%) (P less than 0.01). Therapies proven by repeated clinical trials to be effective in reducing AMI risk were all used less frequently in patients aged at least 70 years: thrombolysis (20 versus 43%); beta-blockers (41 versus 62%); acetylsalicylic acid (71 versus 87%); and nitrates (86 versus 97%). Qualitatively, these age-specific patterns of AMI mortality and therapy were similar to previous studies. Quantitatively, however, comparing 1987 with 1989-90 demonstrated parallel and marked increases in the use of all proven medications in both age groups, ranging from 42 to 230% (P less than 0.01). There was also a significant overall decrease in mortality from the 1987 patient cohort (20%) to the 1989-90 cohort (13%) (P less than 0.05). The decrease in mortality was entirely due to decreased mortality within the group 70 years or older; 35% in 1987 versus 19% in 1989-90 (P less than 0.05). Mortality in the AMI patients younger than 70 years old remained unchanged from 1987 to 1989-90. CONCLUSIONS: Pattern of practice analyses were associated with, and may have contributed to, improved patient care and outcomes in AMI. Increased use of effective AMI medical therapy had a greater benefit in elderly higher risk AMI patients than lower risk younger patients. Persisting age-specific differences in AMI therapy may respond to more direct quality improvement measures, such as critical path management.

The changing clinical profile of coronary artery bypass graft patients, 1970-89.

OBJECTIVE: To review the changing clinical profile of isolated coronary artery bypass graft (CABG) surgery patients at the University of Alberta Hospitals during the past two decades. DESIGN: Data were obtained retrospectively by review of patients' hospital charts and cardiologists' charts. The three patient cohorts consisted of the first 411 consecutive patients who underwent isolated CABG surgery between 1970 and 1974, 302 consecutive patients who had CABG surgery in 1984 and 346 consecutive patients who had the operation in 1989. RESULTS: Patients who underwent CABG surgery in 1984 and 1989 were older than patients undergoing the same operation in the 1970s. Emergency and/or urgent operations and the number of patients with prior myocardial infarct were increased significantly in 1984 and 1989. The incidence of patients with multiple vessel disease and left main stem stenosis increased significantly over the two decades. The number of bypass grafts per patient and the use of internal mammary grafts have increased since 1970. The endarterectomy procedure was performed less frequently in 1984 and 1989. The use of radial artery grafts has been discontinued. Perioperative mortality remained stable throughout the study period despite an increasing incidence of high risk patients. The major cause of death was pump failure. The incidence of peripostoperative myocardial infarct was higher in the 1970s. A multivariate analysis of the 1984 and 1989 cohorts was performed to identify temporal trends in risk factors. Emergency surgery, preoperative heart failure, age (older than 65 years), prior CABG surgery and preoperative renal failure are significant predictors of operative motility. CONCLUSIONS: The clinical profile of patients for isolated CABG surgery has changed over the years. The mortality rate has been stable over two decades despite the advancement of medical and surgical practices, representing a balance of increasingly high risk patients presenting for CABG surgery.

A hospital service population model and its application.

The concepts of hospital service population and its estimation techniques is refined and generalized from a model-building point of view, and the generalized model is applied to the Alberta, Canada, hospital system. The assumptions underlying the so-called relevance and commitment index methods are investigated. A set of computer programs is developed for estimating the service population of Alberta hospitals. The programs use census, patient origin, and hospital statistics related to costs as input, and provide resource allocation and utilization rates on an age-sex adjusted per capita basis for all Alberta general acute hospitals and hospital districts. The estimates based on relevance and commitment index methods are compared and found to be very similar, except at the extreme tail areas of the distribution.

Utilisation of acute care hospital beds by levels of care.

An exploratory analysis of utilisation patterns of acute care hospitals in the Province of Alberta, Canada was carried out to develop a methodology for assessing bed utilisation profiles of acute care hospitals by levels of care. The utilisation of Alberta acute care hospital beds was measured in terms of primary, secondary and tertiary levels of hospital services. Patient origin-destination methodology was applied and a regionalisation perspective employed. The data used for this study were hospital separation abstracts compiled by all Alberta acute care hospitals during year 1986, this coincided with the most recent available Canadian census data. It was estimated that approximately 10-11% of Alberta beds were used for tertiary care as derived from population based utilisation rates and patient flow patterns. With respect to per capita measurement, the number of beds used per 1,000 residents was: 3.5 to 3.9 for primary, 1.2 to 1.6 for secondary, and about 0.6 for tertiary levels of care. Regression analysis revealed that the marginal cost per bed at each level was approximately 75-79, 87-88, and 201-209 thousand Canadian dollars per year in 1986 for primary, secondary and tertiary care respectively. The profiles thus estimated explained about 65% of per bed hospital cost variation.

Utilization of hospital services by the elderly: geriatric crisis in one Canadian single payer system.

As the number and proportion of elderly persons in the Canadian population increase, utilization of health services by the elderly becomes a growing concern for health service insurers, financial managers and policy makers, as well as for care providers. The purpose of this paper is to present the results of a study to analyse the use of hospital services by the elderly in Alberta since the introduction of a universal single payer health care insurance system in 1970. The study period coincides with the implementation of publicly-financed comprehensive medical and hospital insurance programmes for all Alberta residents, making it possible to perform historical and population-based utilization analyses. Thus the data used for the study included all hospital discharge abstracts generated by all Alberta hospitals from 1971 to 1991. Trends in hospital service utilization by the elderly in terms of total number of separations, patient-days, and per case measures such as average length of stay as well as per capita utilization rates were reviewed to identify utilization patterns over the study period. Further, relative per capita utilization measures, in comparison with the base year (1971), age group 15-44, male, metropolitan residents, were derived and historical trends identified. A series of regression analyses were carried out to estimate the effects of age, sex and origin on utilization rates. In addition, for the period of 1984-1991, Diagnosis Related Groups (DRG) case weights were used to measure per capita and per case rates and to analyse historical relative utilization rates over the 8-year period. In general, there has been a significant decline in hospital utilization by Albertans under the publicly-financed single payer system, but utilization rates for elderly have remained high, resulting in high relative utilization rates in comparison with other age groups. It was also noted that per capita utilization rates for rural residents were substantially higher than urban residents. It appears that these higher utilization rates by the elderly and rural residents in combination with tight bed and financial control by the government have been causing significant bed shortage problems for non-elderly elective patients in urban areas.

Socioeconomic risk factors and population-based regional allocation of healthcare funds.

Using the notion of professional uncertainty a population-based proxy need measure for hospital services was developed. Its relationship with socioeconomic variables and Standardized Mortality Ratios (SMR) was investigated in an attempt to develop an adjustment factor for socioeconomic risk factors beyond age-sex adjustment to be used for a population-based healthcare funding formula for Alberta. The data used are 1990, 1991, 1992 vital statistics and hospital separation abstracts, 1991 census data and Refined Diagnosis Related Group (RDRG) case weights. Geographic units studied were the 26 federal electoral districts in Alberta using postal codes as a linkage geo-code between census and hospital utilization and death data. SMRs, age-sex standardized per capita hospital utilization and proxy need rates were derived and correlated with socioeconomic variables derived from the census files. It appears that the poor, the less educated and aboriginals need more hospital services than the affluent, employed and educated, confirming previous findings. The unemployed tend to need more but use fewer services while immigrants and non-white ethnics tend to need and use fewer services. The unemployed, less educated and non-white ethnics are associated with positive correlation with premature mortality (SMR based on deaths under age 75 years), while the employed, highly educated tend to live longer. In general SMRs have positive but very low correlations with utilization and need rates suggesting that SMRs should not be used for resource allocation. Stepwise multiple regression analyses showed that the percentages of unemployed, immigrants, non-whites, aboriginals and those with education less than grade 9 explain about 90% of the variation in age-sex standardized hospital utilization rates. Percentages of unemployed, non-white ethnics, residents with education less than grade 9 and aboriginals explained 71% of variations in age-sex standardized per capita proxy hospital service need measures. Based on the results of regression analyses, a SEAM (Socio-Economic Adjustment Multiplier) scale was developed for utilization (SEAM-U) and proxy needs (SEAM-N). In essence a SEAM is a set of relative value (RV) multipliers applicable to a provincial common per age-sex adjusted capita allocation value to account for the impact of socioeconomic risk factors on hospital service needs or utilization. Finally, the resulting regression equations derived from the 26 Federal electoral district data were applied to Alberta's health regions, regional SEAMs were derived, and the impact of such adjustment was assessed.

Regionalization and hospital utilization: Alberta 1991/2-1996/7.

BACKGROUND: In February 1994 Alberta Health announced a three-year business plan for the radical restructuring of the health care system in Alberta. The business plan outlined large reductions in funding for acute hospital care spending and the establishment of 17 Regional Health Authorities (RHAs). OBJECTIVES: The objectives of this study are to describe for the period 1991/2 to 1996/7: 1) Trends in overall acute hospital utilization by Alberta residents and residents of each of the 17 RHAs. 2) Trends in the provision of acute hospital services by each of the 17 RHAs and the Alberta Cancer Board. 3) Trends in the transfer of patients between RHAs. RESULTS: Between 1991/2 and 1996/7, the age-sex standardized separation rate, the age-sex standardized average length of stay, and age-sex standardized hospital days rate for Alberta residents fell by 25.6%, 18.7%, and 39.5% respectively. The age-standardized hospital days rate fell in all 17 RHAs. The total number of separations (Alberta residents and non-residents) from Alberta acute care facilities fell by 19.6% while the average care intensity for all separations from Alberta acute care facilities rose by 8.7%. The ratio of the highest to lowest average RHA care intensity remained between 1.7 and 1.9 during the study period. RHA self-sufficiency indices increased dramatically in one RHA and remained largely unchanged in the remaining RHAs. RHA import indices decreased for most RHAs. CONCLUSIONS: Large reductions in the use of acute hospital services have occurred in Alberta during the period of major health care restructuring. Further research is needed to examine shifts in services to other sectors and to assess the impact of these reductions on patient outcomes.

NOTE ON THE EQUIVALENCE OF THE SIGNIFICANCE TEST OF THE PARTIAL POINT-BISERIAL CORRELATION AND THE ONE-FACTOR ANALYSIS OF COVARIANCE FOR TWO TREATMENT GROUPS.

An identity is demonstrated between (1) the squared Student's t-statistic obtained as a transformation of the sample point-biserial correlation coefficient relating dichotomous variable, 21, to continuous variable x, with the effects of a third variable, x, partialed out; and (2) the F-statistic resulting from a one-factor, two-group (the y dichotomy) analysis of covariance on the x variable Mth the third variable, x, covaried.

Some computer-based decision support tools for the rehabilitation manager.

The recent introduction of the Management Information System (MIS) guidelines has sparked much interest among health care institutions across Canada regarding proper approaches to the recording and interpretation of various financial and workload indicators. While the benefits of the MIS guidelines are widely acknowledged, much less attention has been directed to how departmental managers can analyze and make use of the vast amount of information generated. In this paper we attempt to review some of the computer-based decision-support tools that may be useful to the manager of the rehabilitation services department in analyzing the various MIS data that are collected. The data are assumed to be available through a computerized rehabilitation information system which includes workload measures. The quantitative models reviewed in this paper include basic descriptive statistics, deviation, trend and what-if-analysis and graph-plotting. Although the use of such tools can assist the rehabilitation manager in the routine decision-making process, it is very important that we ask the right questions and employ the proper model to make the most rational and best decision. In this respect, ongoing training in general problem-solving skills, decision-making processes, and use of computer-based decision-support tools may be very beneficial.

Utilization of hospital services by cardiovascular patients, Alberta, Canada.

Using hospital discharge records, and United States DRG (diagnosis related groups) data, we studied hospital utilization by cardiovascular patients, associated hospital expenditures, and the per capita cost of treating cardiovascular diseases in Alberta, Canada between 1971 and 1986. Expressed in constant 1984 Canadian dollars, the estimated total hospital cost increased from $84 million in 1971 to $131 million in 1986; during this period the Province of Alberta spent about $51 Canadian per resident each year for cardiovascular hospital services. It was noted that rural residents consumed a higher volume of resources per capita than their urban counterparts. A patient origin-destination analysis indicated an increasing dependence of rural patients on urban hospitals for secondary or tertiary care, underscoring the effects of medical technology on referral patterns.

The worth of a screening program: an application of a statistical decision model for the benefit evaluation of screening projects.

A statistical decision model is applied to the benefit evaluation of screening projects to derive an expression which provides upper and lower limits for average benefits in terms of prevalance rates of screen positives and negatives, and the average cost of screening and referral. Possible applications of such a technique are discussed and a numerical example is given.